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ispc/opt.cpp
Matt Pharr 975db80ef6 Add support for pointers to the language. 
Pointers can be either uniform or varying, and behave correspondingly.
e.g.: "uniform float * varying" is a varying pointer to uniform float
data in memory, and "float * uniform" is a uniform pointer to varying
data in memory.  Like other types, pointers are varying by default.

Pointer-based expressions, & and *, sizeof, ->, pointer arithmetic,
and the array/pointer duality all bahave as in C.  Array arguments
to functions are converted to pointers, also like C.

There is a built-in NULL for a null pointer value; conversion from
compile-time constant 0 values to NULL still needs to be implemented.

Other changes:
- Syntax for references has been updated to be C++ style; a useful
  warning is now issued if the "reference" keyword is used.
- It is now illegal to pass a varying lvalue as a reference parameter
  to a function; references are essentially uniform pointers.
  This case had previously been handled via special case call by value
  return code.  That path has been removed, now that varying pointers
  are available to handle this use case (and much more).
- Some stdlib routines have been updated to take pointers as
  arguments where appropriate (e.g. prefetch and the atomics).
  A number of others still need attention.
- All of the examples have been updated
- Many new tests

TODO: documentation
2011-11-27 13:09:59 -08:00

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/*
Copyright (c) 2010-2011, Intel Corporation
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* Neither the name of Intel Corporation nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @file opt.cpp
@brief Implementations of various ispc optimization passes that operate
on the LLVM IR.
*/
#include "opt.h"
#include "ctx.h"
#include "sym.h"
#include "module.h"
#include "util.h"
#include "llvmutil.h"
#include <stdio.h>
#include <map>
#include <set>
#include <llvm/Pass.h>
#include <llvm/Module.h>
#include <llvm/PassManager.h>
#include <llvm/PassRegistry.h>
#include <llvm/Assembly/PrintModulePass.h>
#include <llvm/Function.h>
#include <llvm/BasicBlock.h>
#include <llvm/Instructions.h>
#include <llvm/Intrinsics.h>
#include <llvm/Constants.h>
#include <llvm/Analysis/ConstantFolding.h>
#include <llvm/Target/TargetLibraryInfo.h>
#ifdef LLVM_2_9
#include <llvm/Support/StandardPasses.h>
#else
#include <llvm/Transforms/IPO/PassManagerBuilder.h>
#endif // LLVM_2_8
#include <llvm/ADT/Triple.h>
#include <llvm/Transforms/Scalar.h>
#include <llvm/Transforms/IPO.h>
#include <llvm/Transforms/Utils/BasicBlockUtils.h>
#include <llvm/Target/TargetOptions.h>
#include <llvm/Target/TargetData.h>
#include <llvm/Target/TargetMachine.h>
#include <llvm/Analysis/Verifier.h>
#include <llvm/Support/raw_ostream.h>
#include <llvm/Analysis/DIBuilder.h>
#include <llvm/Analysis/DebugInfo.h>
#include <llvm/Support/Dwarf.h>
#ifdef ISPC_IS_LINUX
#include <alloca.h>
#elif defined(ISPC_IS_WINDOWS)
#include <malloc.h>
#define alloca _alloca
#endif // ISPC_IS_WINDOWS
static llvm::Pass *CreateIntrinsicsOptPass();
static llvm::Pass *CreateGatherScatterFlattenPass();
static llvm::Pass *CreateGatherScatterImprovementsPass();
static llvm::Pass *CreateLowerGatherScatterPass();
static llvm::Pass *CreateLowerMaskedStorePass();
static llvm::Pass *CreateMaskedStoreOptPass();
static llvm::Pass *CreateIsCompileTimeConstantPass(bool isLastTry);
static llvm::Pass *CreateMakeInternalFuncsStaticPass();
///////////////////////////////////////////////////////////////////////////
/** This utility routine copies the metadata (if any) attached to the
'from' instruction in the IR to the 'to' instruction.
For flexibility, this function takes an llvm::Value rather than an
llvm::Instruction for the 'to' parameter; at some places in the code
below, we sometimes use a llvm::Value to start out storing a value and
then later store instructions. If a llvm::Value is passed to this, the
routine just returns without doing anything; if it is in fact an
LLVM::Instruction, then the metadata can be copied to it.
*/
static void
lCopyMetadata(llvm::Value *vto, const llvm::Instruction *from) {
llvm::Instruction *to = llvm::dyn_cast<llvm::Instruction>(vto);
if (!to)
return;
llvm::SmallVector<std::pair<unsigned int, llvm::MDNode *>, 8> metadata;
from->getAllMetadata(metadata);
for (unsigned int i = 0; i < metadata.size(); ++i)
to->setMetadata(metadata[i].first, metadata[i].second);
}
/** We have a protocol with the front-end LLVM IR code generation process
that allows us to encode the source file position that corresponds with
instructions. (For example, this allows us to issue performance
warnings related to things like scatter and gather after optimization
has been performed, so that we aren't warning about scatters and
gathers that have been improved to stores and loads by optimization
passes.) Note that this is slightly redundant with the source file
position encoding generated for debugging symbols, though we don't
always generate debugging information but we do always generate this
position data.
This function finds the SourcePos that the metadata in the instruction
(if present) corresponds to. See the implementation of
FunctionEmitContext::addGSMetadata(), which encodes the source position during
code generation.
@param inst Instruction to try to find the source position of
@param pos Output variable in which to store the position
@returns True if source file position metadata was present and *pos
has been set. False otherwise.
*/
static bool
lGetSourcePosFromMetadata(const llvm::Instruction *inst, SourcePos *pos) {
llvm::MDNode *filename = inst->getMetadata("filename");
llvm::MDNode *first_line = inst->getMetadata("first_line");
llvm::MDNode *first_column = inst->getMetadata("first_column");
llvm::MDNode *last_line = inst->getMetadata("last_line");
llvm::MDNode *last_column = inst->getMetadata("last_column");
if (!filename || !first_line || !first_column || !last_line || !last_column)
return false;
// All of these asserts are things that FunctionEmitContext::addGSMetadata() is
// expected to have done in its operation
llvm::MDString *str = llvm::dyn_cast<llvm::MDString>(filename->getOperand(0));
assert(str);
llvm::ConstantInt *first_lnum =
llvm::dyn_cast<llvm::ConstantInt>(first_line->getOperand(0));
assert(first_lnum);
llvm::ConstantInt *first_colnum =
llvm::dyn_cast<llvm::ConstantInt>(first_column->getOperand(0));
assert(first_column);
llvm::ConstantInt *last_lnum =
llvm::dyn_cast<llvm::ConstantInt>(last_line->getOperand(0));
assert(last_lnum);
llvm::ConstantInt *last_colnum =
llvm::dyn_cast<llvm::ConstantInt>(last_column->getOperand(0));
assert(last_column);
*pos = SourcePos(str->getString().data(), (int)first_lnum->getZExtValue(),
(int)first_colnum->getZExtValue(), (int)last_lnum->getZExtValue(),
(int)last_colnum->getZExtValue());
return true;
}
/** Utility routine that prints out the LLVM IR for everything in the
module. (Used for debugging).
*/
static void
lPrintModuleCode(llvm::Module *module) {
llvm::PassManager ppm;
ppm.add(llvm::createPrintModulePass(&llvm::outs()));
ppm.run(*module);
}
void
Optimize(llvm::Module *module, int optLevel) {
if (g->debugPrint) {
printf("*** Code going into optimization ***\n");
lPrintModuleCode(module);
}
llvm::PassManager optPM;
llvm::FunctionPassManager funcPM(module);
llvm::TargetLibraryInfo *targetLibraryInfo =
new llvm::TargetLibraryInfo(llvm::Triple(module->getTargetTriple()));
optPM.add(targetLibraryInfo);
optPM.add(new llvm::TargetData(module));
#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
optPM.add(llvm::createIndVarSimplifyPass());
#endif
if (optLevel == 0) {
// This is more or less the minimum set of optimizations that we
// need to do to generate code that will actually run. (We can't
// run absolutely no optimizations, since the front-end needs us to
// take the various __pseudo_* functions it has emitted and turn
// them into something that can actually execute.
optPM.add(llvm::createPromoteMemoryToRegisterPass());
optPM.add(CreateGatherScatterFlattenPass());
if (g->opt.disableHandlePseudoMemoryOps == false) {
optPM.add(CreateLowerGatherScatterPass());
optPM.add(CreateLowerMaskedStorePass());
}
optPM.add(CreateIsCompileTimeConstantPass(true));
optPM.add(llvm::createFunctionInliningPass());
optPM.add(CreateMakeInternalFuncsStaticPass());
optPM.add(llvm::createCFGSimplificationPass());
optPM.add(llvm::createGlobalDCEPass());
}
else {
// Otherwise throw the kitchen sink of optimizations at the code.
// This is almost certainly overkill and likely could be reduced,
// but on the other hand trying to remove some of these has
// historically caused performance slowdowns. Benchmark carefully
// if changing these around.
//
// Note in particular that a number of the ispc optimization
// passes are run repeatedly along the way; they often can kick in
// only later in the optimization process as things like constant
// propagation have done their thing, and then when they do kick
// in, they can often open up new opportunities for optimization...
llvm::PassRegistry *registry = llvm::PassRegistry::getPassRegistry();
llvm::initializeCore(*registry);
llvm::initializeScalarOpts(*registry);
llvm::initializeIPO(*registry);
llvm::initializeAnalysis(*registry);
llvm::initializeIPA(*registry);
llvm::initializeTransformUtils(*registry);
llvm::initializeInstCombine(*registry);
llvm::initializeInstrumentation(*registry);
llvm::initializeTarget(*registry);
// Early optimizations to try to reduce the total amount of code to
// work with if we can
optPM.add(CreateGatherScatterFlattenPass());
optPM.add(llvm::createReassociatePass());
optPM.add(llvm::createConstantPropagationPass());
if (!g->opt.disableMaskedStoreOptimizations) {
optPM.add(CreateIntrinsicsOptPass());
optPM.add(CreateMaskedStoreOptPass());
}
optPM.add(llvm::createDeadInstEliminationPass());
optPM.add(llvm::createConstantPropagationPass());
optPM.add(llvm::createDeadInstEliminationPass());
// On to more serious optimizations
optPM.add(llvm::createCFGSimplificationPass());
optPM.add(llvm::createScalarReplAggregatesPass());
optPM.add(llvm::createInstructionCombiningPass());
optPM.add(llvm::createCFGSimplificationPass());
optPM.add(llvm::createPromoteMemoryToRegisterPass());
optPM.add(llvm::createGlobalOptimizerPass());
optPM.add(llvm::createReassociatePass());
optPM.add(llvm::createIPConstantPropagationPass());
optPM.add(llvm::createDeadArgEliminationPass());
optPM.add(llvm::createInstructionCombiningPass());
optPM.add(llvm::createCFGSimplificationPass());
optPM.add(llvm::createPruneEHPass());
optPM.add(llvm::createFunctionAttrsPass());
optPM.add(llvm::createFunctionInliningPass());
optPM.add(llvm::createConstantPropagationPass());
optPM.add(llvm::createDeadInstEliminationPass());
optPM.add(llvm::createCFGSimplificationPass());
optPM.add(llvm::createArgumentPromotionPass());
optPM.add(llvm::createSimplifyLibCallsPass());
optPM.add(llvm::createInstructionCombiningPass());
optPM.add(llvm::createJumpThreadingPass());
optPM.add(llvm::createCFGSimplificationPass());
optPM.add(llvm::createScalarReplAggregatesPass());
optPM.add(llvm::createInstructionCombiningPass());
optPM.add(llvm::createTailCallEliminationPass());
if (!g->opt.disableMaskedStoreOptimizations) {
optPM.add(CreateIntrinsicsOptPass());
optPM.add(CreateMaskedStoreOptPass());
}
optPM.add(CreateLowerMaskedStorePass());
if (!g->opt.disableGatherScatterOptimizations)
optPM.add(CreateGatherScatterImprovementsPass());
if (g->opt.disableHandlePseudoMemoryOps == false) {
optPM.add(CreateLowerMaskedStorePass());
optPM.add(CreateLowerGatherScatterPass());
}
optPM.add(llvm::createFunctionInliningPass());
optPM.add(llvm::createConstantPropagationPass());
optPM.add(CreateIntrinsicsOptPass());
#if defined(LLVM_2_9)
llvm::createStandardModulePasses(&optPM, 3,
false /* opt size */,
true /* unit at a time */,
g->opt.unrollLoops,
true /* simplify lib calls */,
false /* may have exceptions */,
llvm::createFunctionInliningPass());
llvm::createStandardLTOPasses(&optPM, true /* internalize pass */,
true /* inline once again */,
false /* verify after each pass */);
llvm::createStandardFunctionPasses(&optPM, 3);
optPM.add(CreateIsCompileTimeConstantPass(true));
optPM.add(CreateIntrinsicsOptPass());
llvm::createStandardModulePasses(&optPM, 3,
false /* opt size */,
true /* unit at a time */,
g->opt.unrollLoops,
true /* simplify lib calls */,
false /* may have exceptions */,
llvm::createFunctionInliningPass());
#else
llvm::PassManagerBuilder builder;
builder.OptLevel = 3;
builder.Inliner = llvm::createFunctionInliningPass();
if (g->opt.unrollLoops == false)
builder.DisableUnrollLoops = true;
builder.populateFunctionPassManager(funcPM);
builder.populateModulePassManager(optPM);
optPM.add(CreateIsCompileTimeConstantPass(true));
optPM.add(CreateIntrinsicsOptPass());
builder.populateLTOPassManager(optPM, true /* internalize */,
true /* inline once again */);
optPM.add(CreateIsCompileTimeConstantPass(true));
optPM.add(CreateIntrinsicsOptPass());
builder.populateModulePassManager(optPM);
#endif
optPM.add(CreateMakeInternalFuncsStaticPass());
optPM.add(llvm::createGlobalDCEPass());
}
// Finish up by making sure we didn't mess anything up in the IR along
// the way.
optPM.add(llvm::createVerifierPass());
for (llvm::Module::iterator fiter = module->begin(); fiter != module->end();
++fiter)
funcPM.run(*fiter);
optPM.run(*module);
if (g->debugPrint) {
printf("\n*****\nFINAL OUTPUT\n*****\n");
lPrintModuleCode(module);
}
}
///////////////////////////////////////////////////////////////////////////
// IntrinsicsOpt
/** This is a relatively simple optimization pass that does a few small
optimizations that LLVM's x86 optimizer doesn't currently handle.
(Specifically, MOVMSK of a constant can be replaced with the
corresponding constant value, BLENDVPS and AVX masked load/store with
either an 'all on' or 'all off' masks can be replaced with simpler
operations.
@todo The better thing to do would be to submit a patch to LLVM to get
these; they're presumably pretty simple patterns to match.
*/
class IntrinsicsOpt : public llvm::BasicBlockPass {
public:
IntrinsicsOpt();
const char *getPassName() const { return "Intrinsics Cleanup Optimization"; }
bool runOnBasicBlock(llvm::BasicBlock &BB);
static char ID;
private:
struct MaskInstruction {
MaskInstruction(llvm::Function *f) { function = f; }
llvm::Function *function;
};
std::vector<MaskInstruction> maskInstructions;
/** Structure that records everything we need to know about a blend
instruction for this optimization pass.
*/
struct BlendInstruction {
BlendInstruction(llvm::Function *f, int ao, int o0, int o1, int of)
: function(f), allOnMask(ao), op0(o0), op1(o1), opFactor(of) { }
/** Function pointer for the blend instruction */
llvm::Function *function;
/** Mask value for an "all on" mask for this instruction */
int allOnMask;
/** The operand number in the llvm CallInst corresponds to the
first operand to blend with. */
int op0;
/** The operand number in the CallInst corresponding to the second
operand to blend with. */
int op1;
/** The operand in the call inst where the blending factor is
found. */
int opFactor;
};
std::vector<BlendInstruction> blendInstructions;
bool matchesMaskInstruction(llvm::Function *function);
BlendInstruction *matchingBlendInstruction(llvm::Function *function);
};
char IntrinsicsOpt::ID = 0;
llvm::RegisterPass<IntrinsicsOpt> sse("sse-constants", "Intrinsics Cleanup Pass");
IntrinsicsOpt::IntrinsicsOpt()
: BasicBlockPass(ID) {
// All of the mask instructions we may encounter. Note that even if
// compiling for AVX, we may still encounter the regular 4-wide SSE
// MOVMSK instruction.
llvm::Function *sseMovmsk =
llvm::Intrinsic::getDeclaration(m->module, llvm::Intrinsic::x86_sse_movmsk_ps);
maskInstructions.push_back(sseMovmsk);
maskInstructions.push_back(m->module->getFunction("__movmsk"));
#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
llvm::Function *avxMovmsk =
llvm::Intrinsic::getDeclaration(m->module, llvm::Intrinsic::x86_avx_movmsk_ps_256);
assert(avxMovmsk != NULL);
maskInstructions.push_back(avxMovmsk);
#endif
// And all of the blend instructions
blendInstructions.push_back(BlendInstruction(
llvm::Intrinsic::getDeclaration(m->module, llvm::Intrinsic::x86_sse41_blendvps),
0xf, 0, 1, 2));
#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
blendInstructions.push_back(BlendInstruction(
llvm::Intrinsic::getDeclaration(m->module, llvm::Intrinsic::x86_avx_blendv_ps_256),
0xff, 0, 1, 2));
#endif
}
/** Given an llvm::Value represinting a vector mask, see if the value is a
constant. If so, return the integer mask found by taking the high bits
of the mask values in turn and concatenating them into a single integer.
In other words, given the 4-wide mask: < 0xffffffff, 0, 0, 0xffffffff >,
we have 0b1001 = 9.
@todo This will break if we ever do 32-wide compilation, in which case
it don't be possible to distinguish between -1 for "don't know" and
"known and all bits on".
*/
static int
lGetMask(llvm::Value *factor) {
llvm::ConstantVector *cv = llvm::dyn_cast<llvm::ConstantVector>(factor);
if (cv) {
int mask = 0;
llvm::SmallVector<llvm::Constant *, ISPC_MAX_NVEC> elements;
cv->getVectorElements(elements);
for (unsigned int i = 0; i < elements.size(); ++i) {
llvm::APInt intMaskValue;
// SSE has the "interesting" approach of encoding blending
// masks as <n x float>.
llvm::ConstantFP *cf = llvm::dyn_cast<llvm::ConstantFP>(elements[i]);
if (cf) {
llvm::APFloat apf = cf->getValueAPF();
intMaskValue = apf.bitcastToAPInt();
}
else {
// Otherwise get it as an int
llvm::ConstantInt *ci = llvm::dyn_cast<llvm::ConstantInt>(elements[i]);
assert(ci != NULL); // vs return -1 if NULL?
intMaskValue = ci->getValue();
}
// Is the high-bit set? If so, OR in the appropriate bit in
// the result mask
if (intMaskValue.countLeadingOnes() > 0)
mask |= (1 << i);
}
return mask;
}
else if (llvm::isa<llvm::ConstantAggregateZero>(factor))
return 0;
else {
#if 0
llvm::ConstantExpr *ce = llvm::dyn_cast<llvm::ConstantExpr>(factor);
if (ce != NULL) {
llvm::TargetMachine *targetMachine = g->target.GetTargetMachine();
const llvm::TargetData *td = targetMachine->getTargetData();
llvm::Constant *c = llvm::ConstantFoldConstantExpression(ce, td);
c->dump();
factor = c;
}
// else we should be able to handle it above...
assert(!llvm::isa<llvm::Constant>(factor));
#endif
return -1;
}
}
/** Given an llvm::Value, return true if we can determine that it's an
undefined value. This only makes a weak attempt at chasing this down,
only detecting flat-out undef values, and bitcasts of undef values.
@todo Is it worth working harder to find more of these? It starts to
get tricky, since having an undef operand doesn't necessarily mean that
the result will be undefined. (And for that matter, is there an LLVM
call that will do this for us?)
*/
static bool
lIsUndef(llvm::Value *value) {
if (llvm::isa<llvm::UndefValue>(value))
return true;
llvm::BitCastInst *bci = llvm::dyn_cast<llvm::BitCastInst>(value);
if (bci)
return lIsUndef(bci->getOperand(0));
return false;
}
bool
IntrinsicsOpt::runOnBasicBlock(llvm::BasicBlock &bb) {
#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
llvm::Function *avxMaskedLoad32 =
llvm::Intrinsic::getDeclaration(m->module, llvm::Intrinsic::x86_avx_maskload_ps_256);
llvm::Function *avxMaskedLoad64 =
llvm::Intrinsic::getDeclaration(m->module, llvm::Intrinsic::x86_avx_maskload_pd_256);
llvm::Function *avxMaskedStore32 =
llvm::Intrinsic::getDeclaration(m->module, llvm::Intrinsic::x86_avx_maskstore_ps_256);
llvm::Function *avxMaskedStore64 =
llvm::Intrinsic::getDeclaration(m->module, llvm::Intrinsic::x86_avx_maskstore_pd_256);
assert(avxMaskedLoad32 != NULL && avxMaskedStore32 != NULL);
assert(avxMaskedLoad64 != NULL && avxMaskedStore64 != NULL);
#endif
bool modifiedAny = false;
restart:
for (llvm::BasicBlock::iterator iter = bb.begin(), e = bb.end(); iter != e; ++iter) {
llvm::CallInst *callInst = llvm::dyn_cast<llvm::CallInst>(&*iter);
if (!callInst)
continue;
BlendInstruction *blend = matchingBlendInstruction(callInst->getCalledFunction());
if (blend != NULL) {
llvm::Value *v[2] = { callInst->getArgOperand(blend->op0),
callInst->getArgOperand(blend->op1) };
llvm::Value *factor = callInst->getArgOperand(blend->opFactor);
// If the values are the same, then no need to blend..
if (v[0] == v[1]) {
llvm::ReplaceInstWithValue(iter->getParent()->getInstList(),
iter, v[0]);
modifiedAny = true;
goto restart;
}
// If one of the two is undefined, we're allowed to replace
// with the value of the other. (In other words, the only
// valid case is that the blend factor ends up having a value
// that only selects from the defined one of the two operands,
// otherwise the result is undefined and any value is fine,
// ergo the defined one is an acceptable result.)
if (lIsUndef(v[0])) {
llvm::ReplaceInstWithValue(iter->getParent()->getInstList(),
iter, v[1]);
modifiedAny = true;
goto restart;
}
if (lIsUndef(v[1])) {
llvm::ReplaceInstWithValue(iter->getParent()->getInstList(),
iter, v[0]);
modifiedAny = true;
goto restart;
}
int mask = lGetMask(factor);
llvm::Value *value = NULL;
if (mask == 0)
// Mask all off -> replace with the first blend value
value = v[0];
else if (mask == blend->allOnMask)
// Mask all on -> replace with the second blend value
value = v[1];
if (value != NULL) {
llvm::ReplaceInstWithValue(iter->getParent()->getInstList(),
iter, value);
modifiedAny = true;
goto restart;
}
}
else if (matchesMaskInstruction(callInst->getCalledFunction())) {
llvm::Value *factor = callInst->getArgOperand(0);
int mask = lGetMask(factor);
if (mask != -1) {
// If the vector-valued mask has a known value, replace it
// with the corresponding integer mask from its elements
// high bits.
llvm::Value *value = LLVMInt32(mask);
llvm::ReplaceInstWithValue(iter->getParent()->getInstList(),
iter, value);
modifiedAny = true;
goto restart;
}
}
#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
else if (callInst->getCalledFunction() == avxMaskedLoad32 ||
callInst->getCalledFunction() == avxMaskedLoad64) {
llvm::Value *factor = callInst->getArgOperand(1);
int mask = lGetMask(factor);
if (mask == 0) {
// nothing being loaded, replace with undef value
llvm::Type *returnType = callInst->getType();
assert(llvm::isa<llvm::VectorType>(returnType));
llvm::Value *undefValue = llvm::UndefValue::get(returnType);
llvm::ReplaceInstWithValue(iter->getParent()->getInstList(),
iter, undefValue);
modifiedAny = true;
goto restart;
}
else if (mask == 0xff) {
// all lanes active; replace with a regular load
llvm::Type *returnType = callInst->getType();
assert(llvm::isa<llvm::VectorType>(returnType));
// cast the i8 * to the appropriate type
llvm::Value *castPtr =
new llvm::BitCastInst(callInst->getArgOperand(0),
llvm::PointerType::get(returnType, 0),
"ptr2vec", callInst);
lCopyMetadata(castPtr, callInst);
int align = callInst->getCalledFunction() == avxMaskedLoad32 ? 4 : 8;
llvm::Instruction *loadInst =
new llvm::LoadInst(castPtr, "load", false /* not volatile */,
align, (llvm::Instruction *)NULL);
lCopyMetadata(loadInst, callInst);
llvm::ReplaceInstWithInst(callInst, loadInst);
modifiedAny = true;
goto restart;
}
}
else if (callInst->getCalledFunction() == avxMaskedStore32 ||
callInst->getCalledFunction() == avxMaskedStore64) {
// NOTE: mask is the 2nd parameter, not the 3rd one!!
llvm::Value *factor = callInst->getArgOperand(1);
int mask = lGetMask(factor);
if (mask == 0) {
// nothing actually being stored, just remove the inst
callInst->eraseFromParent();
modifiedAny = true;
goto restart;
}
else if (mask == 0xff) {
// all lanes storing, so replace with a regular store
llvm::Value *rvalue = callInst->getArgOperand(2);
llvm::Type *storeType = rvalue->getType();
llvm::Value *castPtr =
new llvm::BitCastInst(callInst->getArgOperand(0),
llvm::PointerType::get(storeType, 0),
"ptr2vec", callInst);
lCopyMetadata(castPtr, callInst);
llvm::StoreInst *storeInst =
new llvm::StoreInst(rvalue, castPtr, (llvm::Instruction *)NULL);
int align = callInst->getCalledFunction() == avxMaskedStore32 ? 4 : 8;
storeInst->setAlignment(align);
lCopyMetadata(storeInst, callInst);
llvm::ReplaceInstWithInst(callInst, storeInst);
modifiedAny = true;
goto restart;
}
}
#endif
}
return modifiedAny;
}
bool
IntrinsicsOpt::matchesMaskInstruction(llvm::Function *function) {
for (unsigned int i = 0; i < maskInstructions.size(); ++i)
if (maskInstructions[i].function != NULL &&
function == maskInstructions[i].function)
return true;
return false;
}
IntrinsicsOpt::BlendInstruction *
IntrinsicsOpt::matchingBlendInstruction(llvm::Function *function) {
for (unsigned int i = 0; i < blendInstructions.size(); ++i)
if (blendInstructions[i].function != NULL &&
function == blendInstructions[i].function)
return &blendInstructions[i];
return NULL;
}
static llvm::Pass *
CreateIntrinsicsOptPass() {
return new IntrinsicsOpt;
}
///////////////////////////////////////////////////////////////////////////
// GatherScatterFlattenOpt
/** When the front-end emits gathers and scatters, it generates an array of
vector-width pointers to represent the set of addresses to read from or
write to. This optimization detects cases when the base pointer is a
uniform pointer or when the indexing is into an array that can be
converted into scatters/gathers from a single base pointer and an array
of offsets.
See for example the comments discussing the __pseudo_gather functions
in builtins.cpp for more information about this.
*/
class GatherScatterFlattenOpt : public llvm::BasicBlockPass {
public:
static char ID;
GatherScatterFlattenOpt() : BasicBlockPass(ID) { }
const char *getPassName() const { return "Gather/Scatter Flattening"; }
bool runOnBasicBlock(llvm::BasicBlock &BB);
};
char GatherScatterFlattenOpt::ID = 0;
llvm::RegisterPass<GatherScatterFlattenOpt> gsf("gs-flatten", "Gather/Scatter Flatten Pass");
/** Given an llvm::Value known to be an integer, return its value as
an int64_t.
*/
static int64_t
lGetIntValue(llvm::Value *offset) {
llvm::ConstantInt *intOffset = llvm::dyn_cast<llvm::ConstantInt>(offset);
assert(intOffset && (intOffset->getBitWidth() == 32 ||
intOffset->getBitWidth() == 64));
return intOffset->getSExtValue();
}
/** This function takes chains of InsertElement instructions along the
lines of:
%v0 = insertelement undef, value_0, i32 index_0
%v1 = insertelement %v1, value_1, i32 index_1
...
%vn = insertelement %vn-1, value_n-1, i32 index_n-1
and initializes the provided elements array such that the i'th
llvm::Value * in the array is the element that was inserted into the
i'th element of the vector.
*/
static void
lFlattenInsertChain(llvm::InsertElementInst *ie, int vectorWidth,
llvm::Value **elements) {
for (int i = 0; i < vectorWidth; ++i)
elements[i] = NULL;
while (ie != NULL) {
int64_t iOffset = lGetIntValue(ie->getOperand(2));
assert(iOffset >= 0 && iOffset < vectorWidth);
assert(elements[iOffset] == NULL);
elements[iOffset] = ie->getOperand(1);
llvm::Value *insertBase = ie->getOperand(0);
ie = llvm::dyn_cast<llvm::InsertElementInst>(insertBase);
if (ie == NULL)
assert(llvm::isa<llvm::UndefValue>(insertBase));
}
}
/** Given a llvm::Value representing a varying pointer, this function
checks to see if all of the elements of the vector have the same value
(i.e. there's a common base pointer). If so, it returns the common
pointer value; otherwise it returns NULL.
*/
static llvm::Value *
lGetBasePointer(llvm::Value *v) {
llvm::InsertElementInst *ie = llvm::dyn_cast<llvm::InsertElementInst>(v);
if (ie != NULL) {
llvm::Value *elements[ISPC_MAX_NVEC];
lFlattenInsertChain(ie, g->target.vectorWidth, elements);
// Make sure none of the elements is undefined.
// TODO: it's probably ok to allow undefined elements and return
// the base pointer if all of the other elements have the same
// value.
for (int i = 0; i < g->target.vectorWidth; ++i)
if (elements[i] == NULL)
return NULL;
// Do all of the elements have the same value?
for (int i = 0; i < g->target.vectorWidth-1; ++i)
if (elements[i] != elements[i+1])
return NULL;
return elements[0];
}
// This case comes up with global/static arrays
llvm::ConstantVector *cv = llvm::dyn_cast<llvm::ConstantVector>(v);
if (cv)
return cv->getSplatValue();
return NULL;
}
/** Given a varying pointer in ptrs, this function checks to see if it can
be determined to be indexing from a common uniform base pointer. If
so, the function returns the base pointer llvm::Value and initializes
*offsets with an int vector of the per-lane offsets
*/
static llvm::Value *
lGetBasePtrAndOffsets(llvm::Value *ptrs, llvm::Value **offsets) {
llvm::Value *base = lGetBasePointer(ptrs);
if (base != NULL) {
// We have a straight up varying pointer with no indexing that's
// actually all the same value.
if (g->target.is32Bit)
*offsets = LLVMInt32Vector(0);
else
*offsets = LLVMInt64Vector((int64_t)0);
return base;
}
llvm::BinaryOperator *bop = llvm::dyn_cast<llvm::BinaryOperator>(ptrs);
if (bop != NULL && bop->getOpcode() == llvm::Instruction::Add) {
// If we have a common pointer plus something, then we're also
// good.
if ((base = lGetBasePointer(bop->getOperand(0))) != NULL) {
*offsets = bop->getOperand(1);
return base;
}
else if ((base = lGetBasePointer(bop->getOperand(1))) != NULL) {
*offsets = bop->getOperand(0);
return base;
}
}
return NULL;
}
struct GSInfo {
GSInfo(const char *pgFuncName, const char *pgboFuncName,
const char *pgbo32FuncName, bool ig)
: isGather(ig) {
func = m->module->getFunction(pgFuncName);
baseOffsetsFunc = m->module->getFunction(pgboFuncName);
baseOffsets32Func = m->module->getFunction(pgbo32FuncName);
}
llvm::Function *func;
llvm::Function *baseOffsetsFunc, *baseOffsets32Func;
const bool isGather;
};
bool
GatherScatterFlattenOpt::runOnBasicBlock(llvm::BasicBlock &bb) {
GSInfo gsFuncs[] = {
GSInfo("__pseudo_gather32_8", "__pseudo_gather_base_offsets32_8",
"__pseudo_gather_base_offsets32_8", true),
GSInfo("__pseudo_gather32_16", "__pseudo_gather_base_offsets32_16",
"__pseudo_gather_base_offsets32_16", true),
GSInfo("__pseudo_gather32_32", "__pseudo_gather_base_offsets32_32",
"__pseudo_gather_base_offsets32_32", true),
GSInfo("__pseudo_gather32_64", "__pseudo_gather_base_offsets32_64",
"__pseudo_gather_base_offsets32_64", true),
GSInfo("__pseudo_scatter32_8", "__pseudo_scatter_base_offsets32_8",
"__pseudo_scatter_base_offsets32_8", false),
GSInfo("__pseudo_scatter32_16", "__pseudo_scatter_base_offsets32_16",
"__pseudo_scatter_base_offsets32_16", false),
GSInfo("__pseudo_scatter32_32", "__pseudo_scatter_base_offsets32_32",
"__pseudo_scatter_base_offsets32_32", false),
GSInfo("__pseudo_scatter32_64", "__pseudo_scatter_base_offsets32_64",
"__pseudo_scatter_base_offsets32_64", false),
GSInfo("__pseudo_gather64_8", "__pseudo_gather_base_offsets64_8",
"__pseudo_gather_base_offsets32_8", true),
GSInfo("__pseudo_gather64_16", "__pseudo_gather_base_offsets64_16",
"__pseudo_gather_base_offsets32_16", true),
GSInfo("__pseudo_gather64_32", "__pseudo_gather_base_offsets64_32",
"__pseudo_gather_base_offsets32_32", true),
GSInfo("__pseudo_gather64_64", "__pseudo_gather_base_offsets64_64",
"__pseudo_gather_base_offsets32_64", true),
GSInfo("__pseudo_scatter64_8", "__pseudo_scatter_base_offsets64_8",
"__pseudo_scatter_base_offsets32_8", false),
GSInfo("__pseudo_scatter64_16", "__pseudo_scatter_base_offsets64_16",
"__pseudo_scatter_base_offsets32_16", false),
GSInfo("__pseudo_scatter64_32", "__pseudo_scatter_base_offsets64_32",
"__pseudo_scatter_base_offsets32_32", false),
GSInfo("__pseudo_scatter64_64", "__pseudo_scatter_base_offsets64_64",
"__pseudo_scatter_base_offsets32_64", false),
};
int numGSFuncs = sizeof(gsFuncs) / sizeof(gsFuncs[0]);
for (int i = 0; i < numGSFuncs; ++i)
assert(gsFuncs[i].func != NULL && gsFuncs[i].baseOffsetsFunc != NULL &&
gsFuncs[i].baseOffsets32Func != NULL);
bool modifiedAny = false;
restart:
// Iterate through all of the instructions in the basic block.
for (llvm::BasicBlock::iterator iter = bb.begin(), e = bb.end(); iter != e; ++iter) {
llvm::CallInst *callInst = llvm::dyn_cast<llvm::CallInst>(&*iter);
// If we don't have a call to one of the
// __pseudo_{gather,scatter}_* functions, then just go on to the
// next instruction.
if (callInst == NULL)
continue;
GSInfo *info = NULL;
for (int i = 0; i < numGSFuncs; ++i)
if (gsFuncs[i].func != NULL &&
callInst->getCalledFunction() == gsFuncs[i].func) {
info = &gsFuncs[i];
break;
}
if (info == NULL)
continue;
// Try to transform the array of pointers to a single base pointer
// and an array of int32 offsets. (All the hard work is done by
// lGetBasePtrAndOffsets).
llvm::Value *ptrs = callInst->getArgOperand(0);
llvm::Value *offsetVector = NULL;
llvm::Value *basePtr = lGetBasePtrAndOffsets(ptrs, &offsetVector);
if (basePtr == NULL || offsetVector == NULL)
// It's actually a fully general gather/scatter with a varying
// set of base pointers, so leave it as is and continune onward
// to the next instruction...
continue;
// Cast the base pointer to a void *, since that's what the
// __pseudo_*_base_offsets_* functions want.
basePtr = new llvm::IntToPtrInst(basePtr, LLVMTypes::VoidPointerType,
"base2void", callInst);
lCopyMetadata(basePtr, callInst);
llvm::Function *gatherScatterFunc = info->baseOffsetsFunc;
if (g->opt.force32BitAddressing) {
// If we're doing 32-bit addressing on a 64-bit target, here we
// will see if we can call one of the 32-bit variants of the
// pseudo gather/scatter functions. Specifically, if the
// offset vector turns out to be an i32 value that was sext'ed
// to be i64 immediately before the scatter/gather, then we
// walk past the sext to get the i32 offset values and then
// call out to the corresponding 32-bit gather/scatter
// function.
llvm::SExtInst *sext = llvm::dyn_cast<llvm::SExtInst>(offsetVector);
if (sext != NULL &&
sext->getOperand(0)->getType() == LLVMTypes::Int32VectorType) {
offsetVector = sext->getOperand(0);
gatherScatterFunc = info->baseOffsets32Func;
}
}
if (info->isGather) {
llvm::Value *mask = callInst->getArgOperand(1);
// Generate a new function call to the next pseudo gather
// base+offsets instruction. Note that we're passing a NULL
// llvm::Instruction to llvm::CallInst::Create; this means that
// the instruction isn't inserted into a basic block and that
// way we can then call ReplaceInstWithInst().
llvm::Value *newArgs[3] = { basePtr, offsetVector, mask };
#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
llvm::ArrayRef<llvm::Value *> newArgArray(&newArgs[0], &newArgs[3]);
llvm::Instruction *newCall =
llvm::CallInst::Create(gatherScatterFunc, newArgArray, "newgather",
(llvm::Instruction *)NULL);
#else
llvm::Instruction *newCall =
llvm::CallInst::Create(gatherScatterFunc, &newArgs[0], &newArgs[3],
"newgather");
#endif
lCopyMetadata(newCall, callInst);
llvm::ReplaceInstWithInst(callInst, newCall);
}
else {
llvm::Value *mask = callInst->getArgOperand(2);
llvm::Value *rvalue = callInst->getArgOperand(1);
// Generate a new function call to the next pseudo scatter
// base+offsets instruction. See above for why passing NULL
// for the Instruction * is intended.
llvm::Value *newArgs[4] = { basePtr, offsetVector, rvalue, mask };
#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
llvm::ArrayRef<llvm::Value *> newArgArray(&newArgs[0], &newArgs[4]);
llvm::Instruction *newCall =
llvm::CallInst::Create(gatherScatterFunc, newArgArray, "",
(llvm::Instruction *)NULL);
#else
llvm::Instruction *newCall =
llvm::CallInst::Create(gatherScatterFunc, &newArgs[0],
&newArgs[4]);
#endif
lCopyMetadata(newCall, callInst);
llvm::ReplaceInstWithInst(callInst, newCall);
}
modifiedAny = true;
goto restart;
}
return modifiedAny;
}
static llvm::Pass *
CreateGatherScatterFlattenPass() {
return new GatherScatterFlattenOpt;
}
///////////////////////////////////////////////////////////////////////////
// MaskedStoreOptPass
/** Masked stores are generally more complex than regular stores; for
example, they require multiple instructions to simulate under SSE.
This optimization detects cases where masked stores can be replaced
with regular stores or removed entirely, for the cases of an 'all on'
mask and an 'all off' mask, respectively.
*/
class MaskedStoreOptPass : public llvm::BasicBlockPass {
public:
static char ID;
MaskedStoreOptPass() : BasicBlockPass(ID) { }
const char *getPassName() const { return "Masked Store Scalarize"; }
bool runOnBasicBlock(llvm::BasicBlock &BB);
};
char MaskedStoreOptPass::ID = 0;
llvm::RegisterPass<MaskedStoreOptPass> mss("masked-store-scalarize",
"Masked Store Scalarize Pass");
struct MSInfo {
MSInfo(const char *name, const int a)
: align(a) {
func = m->module->getFunction(name);
assert(func != NULL);
}
llvm::Function *func;
const int align;
};
bool
MaskedStoreOptPass::runOnBasicBlock(llvm::BasicBlock &bb) {
MSInfo msInfo[] = {
MSInfo("__pseudo_masked_store_8", 1),
MSInfo("__pseudo_masked_store_16", 2),
MSInfo("__pseudo_masked_store_32", 4),
MSInfo("__pseudo_masked_store_64", 8),
MSInfo("__masked_store_blend_8", 1),
MSInfo("__masked_store_blend_16", 2),
MSInfo("__masked_store_blend_32", 4),
MSInfo("__masked_store_blend_64", 8),
MSInfo("__masked_store_8", 1),
MSInfo("__masked_store_16", 2),
MSInfo("__masked_store_32", 4),
MSInfo("__masked_store_64", 8)
};
bool modifiedAny = false;
restart:
// Iterate over all of the instructions to look for one of the various
// masked store functions
for (llvm::BasicBlock::iterator iter = bb.begin(), e = bb.end(); iter != e; ++iter) {
llvm::CallInst *callInst = llvm::dyn_cast<llvm::CallInst>(&*iter);
if (!callInst)
continue;
llvm::Function *called = callInst->getCalledFunction();
int nMSFuncs = sizeof(msInfo) / sizeof(msInfo[0]);
MSInfo *info = NULL;
for (int i = 0; i < nMSFuncs; ++i) {
if (msInfo[i].func != NULL && called == msInfo[i].func) {
info = &msInfo[i];
break;
}
}
if (info == NULL)
continue;
// Got one; grab the operands
llvm::Value *lvalue = callInst->getArgOperand(0);
llvm::Value *rvalue = callInst->getArgOperand(1);
llvm::Value *mask = callInst->getArgOperand(2);
int allOnMask = (1 << g->target.vectorWidth) - 1;
int maskAsInt = lGetMask(mask);
if (maskAsInt == 0) {
// Zero mask - no-op, so remove the store completely. (This
// may in turn lead to being able to optimize out instructions
// that compute the rvalue...)
callInst->eraseFromParent();
modifiedAny = true;
goto restart;
}
else if (maskAsInt == allOnMask) {
// The mask is all on, so turn this into a regular store
LLVM_TYPE_CONST llvm::Type *rvalueType = rvalue->getType();
LLVM_TYPE_CONST llvm::Type *ptrType =
llvm::PointerType::get(rvalueType, 0);
lvalue = new llvm::BitCastInst(lvalue, ptrType, "lvalue_to_ptr_type", callInst);
lCopyMetadata(lvalue, callInst);
llvm::Instruction *store =
new llvm::StoreInst(rvalue, lvalue, false /* not volatile */,
info->align);
lCopyMetadata(store, callInst);
llvm::ReplaceInstWithInst(callInst, store);
modifiedAny = true;
goto restart;
}
}
return modifiedAny;
}
static llvm::Pass *
CreateMaskedStoreOptPass() {
return new MaskedStoreOptPass;
}
///////////////////////////////////////////////////////////////////////////
// LowerMaskedStorePass
/** When the front-end needs to do a masked store, it emits a
__pseudo_masked_store* call as a placeholder. This pass lowers these
calls to either __masked_store* or __masked_store_blend* calls.
*/
class LowerMaskedStorePass : public llvm::BasicBlockPass {
public:
static char ID;
LowerMaskedStorePass() : BasicBlockPass(ID) { }
const char *getPassName() const { return "Lower Masked Stores"; }
bool runOnBasicBlock(llvm::BasicBlock &BB);
};
char LowerMaskedStorePass::ID = 0;
llvm::RegisterPass<LowerMaskedStorePass> lms("masked-store-lower",
"Lower Masked Store Pass");
/** This routine attempts to determine if the given pointer in lvalue is
pointing to stack-allocated memory. It's conservative in that it
should never return true for non-stack allocated memory, but may return
false for memory that actually is stack allocated. The basic strategy
is to traverse through the operands and see if the pointer originally
comes from an AllocaInst.
*/
static bool
lIsStackVariablePointer(llvm::Value *lvalue) {
llvm::BitCastInst *bc = llvm::dyn_cast<llvm::BitCastInst>(lvalue);
if (bc)
return lIsStackVariablePointer(bc->getOperand(0));
else {
llvm::AllocaInst *ai = llvm::dyn_cast<llvm::AllocaInst>(lvalue);
if (ai)
return true;
else {
llvm::GetElementPtrInst *gep = llvm::dyn_cast<llvm::GetElementPtrInst>(lvalue);
if (gep)
return lIsStackVariablePointer(gep->getOperand(0));
else
return false;
}
}
}
struct LMSInfo {
LMSInfo(const char *pname, const char *bname, const char *msname) {
pseudoFunc = m->module->getFunction(pname);
blendFunc = m->module->getFunction(bname);
maskedStoreFunc = m->module->getFunction(msname);
assert(pseudoFunc != NULL && blendFunc != NULL &&
maskedStoreFunc != NULL);
}
llvm::Function *pseudoFunc;
llvm::Function *blendFunc;
llvm::Function *maskedStoreFunc;
};
bool
LowerMaskedStorePass::runOnBasicBlock(llvm::BasicBlock &bb) {
LMSInfo msInfo[] = {
LMSInfo("__pseudo_masked_store_8", "__masked_store_blend_8",
"__masked_store_8"),
LMSInfo("__pseudo_masked_store_16", "__masked_store_blend_16",
"__masked_store_16"),
LMSInfo("__pseudo_masked_store_32", "__masked_store_blend_32",
"__masked_store_32"),
LMSInfo("__pseudo_masked_store_64", "__masked_store_blend_64",
"__masked_store_64")
};
bool modifiedAny = false;
restart:
for (llvm::BasicBlock::iterator iter = bb.begin(), e = bb.end(); iter != e; ++iter) {
// Iterate through all of the instructions and look for
// __pseudo_masked_store_* calls.
llvm::CallInst *callInst = llvm::dyn_cast<llvm::CallInst>(&*iter);
if (callInst == NULL)
continue;
LMSInfo *info = NULL;
for (unsigned int i = 0; i < sizeof(msInfo) / sizeof(msInfo[0]); ++i) {
if (msInfo[i].pseudoFunc != NULL &&
callInst->getCalledFunction() == msInfo[i].pseudoFunc) {
info = &msInfo[i];
break;
}
}
if (info == NULL)
continue;
llvm::Value *lvalue = callInst->getArgOperand(0);
llvm::Value *rvalue = callInst->getArgOperand(1);
llvm::Value *mask = callInst->getArgOperand(2);
// We need to choose between doing the load + blend + store trick,
// or serializing the masked store. Even on targets with a native
// masked store instruction, this is preferable since it lets us
// keep values in registers rather than going out to the stack.
bool doBlend = (!g->opt.disableBlendedMaskedStores ||
lIsStackVariablePointer(lvalue));
// Generate the call to the appropriate masked store function and
// replace the __pseudo_* one with it.
llvm::Function *fms = doBlend ? info->blendFunc : info->maskedStoreFunc;
llvm::Value *args[3] = { lvalue, rvalue, mask };
#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
llvm::ArrayRef<llvm::Value *> newArgArray(&args[0], &args[3]);
llvm::Instruction *inst = llvm::CallInst::Create(fms, newArgArray, "",
callInst);
#else
llvm::Instruction *inst = llvm::CallInst::Create(fms, &args[0], &args[3], "",
callInst);
#endif
lCopyMetadata(inst, callInst);
callInst->eraseFromParent();
modifiedAny = true;
goto restart;
}
return modifiedAny;
}
static llvm::Pass *
CreateLowerMaskedStorePass() {
return new LowerMaskedStorePass;
}
///////////////////////////////////////////////////////////////////////////
// GSImprovementsPass
/** After earlier optimization passes have run, we are sometimes able to
determine that gathers/scatters are actually accessing memory in a more
regular fashion and then change the operation to something simpler and
more efficient. For example, if all of the lanes in a gather are
reading from the same location, we can instead do a scalar load and
broadcast. This pass examines gathers and scatters and tries to
simplify them if at all possible.
@todo Currently, this only looks for all program instances going to the
same location and all going to a linear sequence of locations in
memory. There are a number of other cases that might make sense to
look for, including things that could be handled with a vector load +
shuffle or things that could be handled with hybrids of e.g. 2 4-wide
vector loads with AVX, etc.
*/
class GSImprovementsPass : public llvm::BasicBlockPass {
public:
static char ID;
GSImprovementsPass() : BasicBlockPass(ID) { }
const char *getPassName() const { return "Gather/Scatter Improvements"; }
bool runOnBasicBlock(llvm::BasicBlock &BB);
};
char GSImprovementsPass::ID = 0;
llvm::RegisterPass<GSImprovementsPass> gsi("gs-improvements",
"Gather/Scatter Improvements Pass");
/** Conservative test to see if two llvm::Values are equal. There are
(potentially many) cases where the two values actually are equal but
this will return false. However, if it does return true, the two
vectors definitely are equal.
@todo This seems to catch all of the cases we currently need it for in
practice, but it's be nice to make it a little more robust/general. In
general, though, a little something called the halting problem means we
won't get all of them.
*/
static bool
lValuesAreEqual(llvm::Value *v0, llvm::Value *v1,
std::vector<llvm::PHINode *> &seenPhi0,
std::vector<llvm::PHINode *> &seenPhi1) {
// Thanks to the fact that LLVM hashes and returns the same pointer for
// constants (of all sorts, even constant expressions), this first test
// actually catches a lot of cases. LLVM's SSA form also helps a lot
// with this..
if (v0 == v1)
return true;
assert(seenPhi0.size() == seenPhi1.size());
for (unsigned int i = 0; i < seenPhi0.size(); ++i)
if (v0 == seenPhi0[i] && v1 == seenPhi1[i])
return true;
llvm::BinaryOperator *bo0 = llvm::dyn_cast<llvm::BinaryOperator>(v0);
llvm::BinaryOperator *bo1 = llvm::dyn_cast<llvm::BinaryOperator>(v1);
if (bo0 != NULL && bo1 != NULL) {
if (bo0->getOpcode() != bo1->getOpcode())
return false;
return (lValuesAreEqual(bo0->getOperand(0), bo1->getOperand(0),
seenPhi0, seenPhi1) &&
lValuesAreEqual(bo0->getOperand(1), bo1->getOperand(1),
seenPhi0, seenPhi1));
}
llvm::PHINode *phi0 = llvm::dyn_cast<llvm::PHINode>(v0);
llvm::PHINode *phi1 = llvm::dyn_cast<llvm::PHINode>(v1);
if (phi0 != NULL && phi1 != NULL) {
if (phi0->getNumIncomingValues() != phi1->getNumIncomingValues())
return false;
seenPhi0.push_back(phi0);
seenPhi1.push_back(phi1);
unsigned int numIncoming = phi0->getNumIncomingValues();
// Check all of the incoming values: if all of them are all equal,
// then we're good.
bool anyFailure = false;
for (unsigned int i = 0; i < numIncoming; ++i) {
assert(phi0->getIncomingBlock(i) == phi1->getIncomingBlock(i));
if (!lValuesAreEqual(phi0->getIncomingValue(i),
phi1->getIncomingValue(i), seenPhi0, seenPhi1)) {
anyFailure = true;
break;
}
}
seenPhi0.pop_back();
seenPhi1.pop_back();
return !anyFailure;
}
return false;
}
/** Tests to see if all of the elements of the vector in the 'v' parameter
are equal. Like lValuesAreEqual(), this is a conservative test and may
return false for arrays where the values are actually all equal. */
static bool
lVectorValuesAllEqual(llvm::Value *v, int vectorLength,
std::vector<llvm::PHINode *> &seenPhis) {
if (llvm::isa<llvm::ConstantAggregateZero>(v))
return true;
llvm::ConstantVector *cv = llvm::dyn_cast<llvm::ConstantVector>(v);
if (cv != NULL)
return (cv->getSplatValue() != NULL);
llvm::BinaryOperator *bop = llvm::dyn_cast<llvm::BinaryOperator>(v);
if (bop != NULL)
return (lVectorValuesAllEqual(bop->getOperand(0), vectorLength,
seenPhis) &&
lVectorValuesAllEqual(bop->getOperand(1), vectorLength,
seenPhis));
llvm::CastInst *cast = llvm::dyn_cast<llvm::CastInst>(v);
if (cast != NULL)
return lVectorValuesAllEqual(cast->getOperand(0), vectorLength,
seenPhis);
llvm::InsertElementInst *ie = llvm::dyn_cast<llvm::InsertElementInst>(v);
if (ie != NULL) {
llvm::Value *elements[ISPC_MAX_NVEC];
lFlattenInsertChain(ie, vectorLength, elements);
for (int i = 0; i < vectorLength-1; ++i) {
// TODO: It's not clear what to do in this case (which
// corresponds to elements of the vector being undef). It is
// probably to just ignore undef elements and return true if
// all of the other ones are equal, but it'd be nice to have
// some test cases to verify this.
assert(elements[i] != NULL && elements[i+1] != NULL);
std::vector<llvm::PHINode *> seenPhi0;
std::vector<llvm::PHINode *> seenPhi1;
if (lValuesAreEqual(elements[i], elements[i+1], seenPhi0,
seenPhi1) == false)
return false;
}
return true;
}
llvm::PHINode *phi = llvm::dyn_cast<llvm::PHINode>(v);
if (phi) {
for (unsigned int i = 0; i < seenPhis.size(); ++i)
if (seenPhis[i] == phi)
return true;
seenPhis.push_back(phi);
unsigned int numIncoming = phi->getNumIncomingValues();
// Check all of the incoming values: if all of them are all equal,
// then we're good.
for (unsigned int i = 0; i < numIncoming; ++i) {
if (!lVectorValuesAllEqual(phi->getIncomingValue(i), vectorLength,
seenPhis)) {
seenPhis.pop_back();
return false;
}
}
seenPhis.pop_back();
return true;
}
assert(!llvm::isa<llvm::Constant>(v));
if (llvm::isa<llvm::CallInst>(v) || llvm::isa<llvm::LoadInst>(v) ||
!llvm::isa<llvm::Instruction>(v))
return false;
llvm::ShuffleVectorInst *shuffle = llvm::dyn_cast<llvm::ShuffleVectorInst>(v);
if (shuffle != NULL) {
llvm::Value *indices = shuffle->getOperand(2);
if (lVectorValuesAllEqual(indices, vectorLength, seenPhis))
// The easy case--just a smear of the same element across the
// whole vector.
return true;
// TODO: handle more general cases?
return false;
}
#if 0
fprintf(stderr, "all equal: ");
v->dump();
fprintf(stderr, "\n");
llvm::Instruction *inst = llvm::dyn_cast<llvm::Instruction>(v);
if (inst) {
inst->getParent()->dump();
fprintf(stderr, "\n");
fprintf(stderr, "\n");
}
#endif
return false;
}
/** Given a vector of compile-time constant integer values, test to see if
they are a linear sequence of constant integers starting from an
arbirary value but then having a step of value "stride" between
elements.
*/
static bool
lVectorIsLinearConstantInts(llvm::ConstantVector *cv, int vectorLength,
int stride) {
// Flatten the vector out into the elements array
llvm::SmallVector<llvm::Constant *, ISPC_MAX_NVEC> elements;
cv->getVectorElements(elements);
assert((int)elements.size() == vectorLength);
llvm::ConstantInt *ci = llvm::dyn_cast<llvm::ConstantInt>(elements[0]);
if (ci == NULL)
// Not a vector of integers
return false;
int64_t prevVal = ci->getSExtValue();
// For each element in the array, see if it is both a ConstantInt and
// if the difference between it and the value of the previous element
// is stride. If not, fail.
for (int i = 1; i < vectorLength; ++i) {
ci = llvm::dyn_cast<llvm::ConstantInt>(elements[i]);
if (ci == NULL)
return false;
int64_t nextVal = ci->getSExtValue();
if (prevVal + stride != nextVal)
return false;
prevVal = nextVal;
}
return true;
}
static bool lVectorIsLinear(llvm::Value *v, int vectorLength, int stride,
std::vector<llvm::PHINode *> &seenPhis);
/** Checks to see if (op0 * op1) is a linear vector where the result is a
vector with values that increase by stride.
*/
static bool
lCheckMulForLinear(llvm::Value *op0, llvm::Value *op1, int vectorLength,
int stride, std::vector<llvm::PHINode *> &seenPhis) {
// Is the first operand a constant integer value splatted across all of
// the lanes?
llvm::ConstantVector *cv = llvm::dyn_cast<llvm::ConstantVector>(op0);
if (cv == NULL)
return false;
llvm::ConstantInt *splat =
llvm::dyn_cast<llvm::ConstantInt>(cv->getSplatValue());
if (splat == NULL)
return false;
// If the splat value doesn't evenly divide the stride we're looking
// for, there's no way that we can get the linear sequence we're
// looking or.
int64_t splatVal = splat->getSExtValue();
if (splatVal == 0 || splatVal > stride || (stride % splatVal) != 0)
return false;
// Check to see if the other operand is a linear vector with stride
// given by stride/splatVal.
return lVectorIsLinear(op1, vectorLength, stride / splatVal, seenPhis);
}
/** Given vector of integer-typed values, see if the elements of the array
have a step of 'stride' between their values. This function tries to
handle as many possibilities as possible, including things like all
elements equal to some non-constant value plus an integer offset, etc.
*/
static bool
lVectorIsLinear(llvm::Value *v, int vectorLength, int stride,
std::vector<llvm::PHINode *> &seenPhis) {
// First try the easy case: if the values are all just constant
// integers and have the expected stride between them, then we're done.
llvm::ConstantVector *cv = llvm::dyn_cast<llvm::ConstantVector>(v);
if (cv != NULL)
return lVectorIsLinearConstantInts(cv, vectorLength, stride);
llvm::BinaryOperator *bop = llvm::dyn_cast<llvm::BinaryOperator>(v);
if (bop != NULL) {
// FIXME: is it right to pass the seenPhis to the all equal check as well??
llvm::Value *op0 = bop->getOperand(0), *op1 = bop->getOperand(1);
if (bop->getOpcode() == llvm::Instruction::Add)
// There are two cases to check if we have an add:
//
// programIndex + unif -> ascending linear seqeuence
// unif + programIndex -> ascending linear sequence
return ((lVectorIsLinear(op0, vectorLength, stride, seenPhis) &&
lVectorValuesAllEqual(op1, vectorLength, seenPhis)) ||
(lVectorIsLinear(op1, vectorLength, stride, seenPhis) &&
lVectorValuesAllEqual(op0, vectorLength, seenPhis)));
else if (bop->getOpcode() == llvm::Instruction::Sub)
// For subtraction, we only match:
//
// programIndex - unif -> ascending linear seqeuence
//
// In the future, we could also look for:
// unif - programIndex -> *descending* linear seqeuence
// And generate code for that as a vector load + shuffle.
return (lVectorIsLinear(bop->getOperand(0), vectorLength,
stride, seenPhis) &&
lVectorValuesAllEqual(bop->getOperand(1), vectorLength,
seenPhis));
else if (bop->getOpcode() == llvm::Instruction::Mul)
// Multiplies are a bit trickier, so are handled in a separate
// function.
return (lCheckMulForLinear(op0, op1, vectorLength, stride, seenPhis) ||
lCheckMulForLinear(op1, op0, vectorLength, stride, seenPhis));
else
return false;
}
llvm::CastInst *ci = llvm::dyn_cast<llvm::CastInst>(v);
if (ci != NULL)
return lVectorIsLinear(ci->getOperand(0), vectorLength,
stride, seenPhis);
if (llvm::isa<llvm::CallInst>(v) || llvm::isa<llvm::LoadInst>(v))
return false;
llvm::PHINode *phi = llvm::dyn_cast<llvm::PHINode>(v);
if (phi != NULL) {
for (unsigned int i = 0; i < seenPhis.size(); ++i)
if (seenPhis[i] == phi)
return true;
seenPhis.push_back(phi);
unsigned int numIncoming = phi->getNumIncomingValues();
// Check all of the incoming values: if all of them are all equal,
// then we're good.
for (unsigned int i = 0; i < numIncoming; ++i) {
if (!lVectorIsLinear(phi->getIncomingValue(i), vectorLength, stride,
seenPhis)) {
seenPhis.pop_back();
return false;
}
}
seenPhis.pop_back();
return true;
}
// TODO: is any reason to worry about these?
if (llvm::isa<llvm::InsertElementInst>(v))
return false;
// TODO: we could also handle shuffles, but we haven't yet seen any
// cases where doing so would detect cases where actually have a linear
// vector.
llvm::ShuffleVectorInst *shuffle = llvm::dyn_cast<llvm::ShuffleVectorInst>(v);
if (shuffle != NULL)
return false;
#if 0
fprintf(stderr, "linear check: ");
v->dump();
fprintf(stderr, "\n");
llvm::Instruction *inst = llvm::dyn_cast<llvm::Instruction>(v);
if (inst) {
inst->getParent()->dump();
fprintf(stderr, "\n");
fprintf(stderr, "\n");
}
#endif
return false;
}
struct GatherImpInfo {
GatherImpInfo(const char *pName, const char *lbName, const char *lmName,
int a)
: align(a) {
pseudoFunc = m->module->getFunction(pName);
loadBroadcastFunc = m->module->getFunction(lbName);
loadMaskedFunc = m->module->getFunction(lmName);
assert(pseudoFunc != NULL && loadBroadcastFunc != NULL &&
loadMaskedFunc != NULL);
}
llvm::Function *pseudoFunc;
llvm::Function *loadBroadcastFunc;
llvm::Function *loadMaskedFunc;
const int align;
};
struct ScatterImpInfo {
ScatterImpInfo(const char *pName, const char *msName,
LLVM_TYPE_CONST llvm::Type *vpt, int a)
: align(a) {
pseudoFunc = m->module->getFunction(pName);
maskedStoreFunc = m->module->getFunction(msName);
vecPtrType = vpt;
assert(pseudoFunc != NULL && maskedStoreFunc != NULL);
}
llvm::Function *pseudoFunc;
llvm::Function *maskedStoreFunc;
LLVM_TYPE_CONST llvm::Type *vecPtrType;
const int align;
};
bool
GSImprovementsPass::runOnBasicBlock(llvm::BasicBlock &bb) {
GatherImpInfo gInfo[] = {
GatherImpInfo("__pseudo_gather_base_offsets32_8", "__load_and_broadcast_8",
"__load_masked_8", 1),
GatherImpInfo("__pseudo_gather_base_offsets32_16", "__load_and_broadcast_16",
"__load_masked_16", 2),
GatherImpInfo("__pseudo_gather_base_offsets32_32", "__load_and_broadcast_32",
"__load_masked_32", 4),
GatherImpInfo("__pseudo_gather_base_offsets32_64", "__load_and_broadcast_64",
"__load_masked_64", 8),
GatherImpInfo("__pseudo_gather_base_offsets64_8", "__load_and_broadcast_8",
"__load_masked_8", 1),
GatherImpInfo("__pseudo_gather_base_offsets64_16", "__load_and_broadcast_16",
"__load_masked_16", 2),
GatherImpInfo("__pseudo_gather_base_offsets64_32", "__load_and_broadcast_32",
"__load_masked_32", 4),
GatherImpInfo("__pseudo_gather_base_offsets64_64", "__load_and_broadcast_64",
"__load_masked_64", 8)
};
ScatterImpInfo sInfo[] = {
ScatterImpInfo("__pseudo_scatter_base_offsets32_8", "__pseudo_masked_store_8",
LLVMTypes::Int8VectorPointerType, 1),
ScatterImpInfo("__pseudo_scatter_base_offsets32_16", "__pseudo_masked_store_16",
LLVMTypes::Int16VectorPointerType, 2),
ScatterImpInfo("__pseudo_scatter_base_offsets32_32", "__pseudo_masked_store_32",
LLVMTypes::Int32VectorPointerType, 4),
ScatterImpInfo("__pseudo_scatter_base_offsets32_64", "__pseudo_masked_store_64",
LLVMTypes::Int64VectorPointerType, 8),
ScatterImpInfo("__pseudo_scatter_base_offsets64_8", "__pseudo_masked_store_8",
LLVMTypes::Int8VectorPointerType, 1),
ScatterImpInfo("__pseudo_scatter_base_offsets64_16", "__pseudo_masked_store_16",
LLVMTypes::Int16VectorPointerType, 2),
ScatterImpInfo("__pseudo_scatter_base_offsets64_32", "__pseudo_masked_store_32",
LLVMTypes::Int32VectorPointerType, 4),
ScatterImpInfo("__pseudo_scatter_base_offsets64_64", "__pseudo_masked_store_64",
LLVMTypes::Int64VectorPointerType, 8)
};
bool modifiedAny = false;
restart:
for (llvm::BasicBlock::iterator iter = bb.begin(), e = bb.end(); iter != e; ++iter) {
// Iterate over all of the instructions and look for calls to
// __pseudo_*_base_offsets_* calls.
llvm::CallInst *callInst = llvm::dyn_cast<llvm::CallInst>(&*iter);
if (callInst == NULL)
continue;
llvm::Function *calledFunc = callInst->getCalledFunction();
GatherImpInfo *gatherInfo = NULL;
ScatterImpInfo *scatterInfo = NULL;
for (unsigned int i = 0; i < sizeof(gInfo) / sizeof(gInfo[0]); ++i) {
if (gInfo[i].pseudoFunc != NULL &&
calledFunc == gInfo[i].pseudoFunc) {
gatherInfo = &gInfo[i];
break;
}
}
for (unsigned int i = 0; i < sizeof(sInfo) / sizeof(sInfo[0]); ++i) {
if (sInfo[i].pseudoFunc != NULL &&
calledFunc == sInfo[i].pseudoFunc) {
scatterInfo = &sInfo[i];
break;
}
}
if (gatherInfo == NULL && scatterInfo == NULL)
continue;
SourcePos pos;
bool ok = lGetSourcePosFromMetadata(callInst, &pos);
assert(ok);
llvm::Value *base = callInst->getArgOperand(0);
llvm::Value *offsets = callInst->getArgOperand(1);
llvm::Value *mask = callInst->getArgOperand((gatherInfo != NULL) ? 2 : 3);
{
std::vector<llvm::PHINode *> seenPhis;
if (lVectorValuesAllEqual(offsets, g->target.vectorWidth, seenPhis)) {
// If all the offsets are equal, then compute the single
// pointer they all represent based on the first one of them
// (arbitrarily).
llvm::Value *firstOffset =
llvm::ExtractElementInst::Create(offsets, LLVMInt32(0), "first_offset",
callInst);
llvm::Value *indices[1] = { firstOffset };
#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
llvm::ArrayRef<llvm::Value *> arrayRef(&indices[0], &indices[1]);
llvm::Value *ptr =
llvm::GetElementPtrInst::Create(base, arrayRef, "ptr", callInst);
#else
llvm::Value *ptr =
llvm::GetElementPtrInst::Create(base, &indices[0], &indices[1],
"ptr", callInst);
#endif
lCopyMetadata(ptr, callInst);
if (gatherInfo != NULL) {
// A gather with everyone going to the same location is
// handled as a scalar load and broadcast across the lanes.
// Note that we do still have to pass the mask to the
// __load_and_broadcast_* functions, since they shouldn't
// access memory if the mask is all off (the location may
// be invalid in that case).
Debug(pos, "Transformed gather to scalar load and broadcast!");
llvm::Value *args[2] = { ptr, mask };
#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
llvm::ArrayRef<llvm::Value *> newArgArray(&args[0], &args[2]);
llvm::Instruction *newCall =
llvm::CallInst::Create(gatherInfo->loadBroadcastFunc, newArgArray,
"load_broadcast", (llvm::Instruction *)NULL);
#else
llvm::Instruction *newCall =
llvm::CallInst::Create(gatherInfo->loadBroadcastFunc, &args[0],
&args[2], "load_broadcast");
#endif
lCopyMetadata(newCall, callInst);
llvm::ReplaceInstWithInst(callInst, newCall);
}
else {
// A scatter with everyone going to the same location is
// undefined. Issue a warning and arbitrarily let the
// first guy win.
Warning(pos, "Undefined behavior: all program instances are "
"writing to the same location!");
llvm::Value *rvalue = callInst->getArgOperand(2);
llvm::Value *first =
llvm::ExtractElementInst::Create(rvalue, LLVMInt32(0), "rvalue_first",
callInst);
lCopyMetadata(first, callInst);
ptr = new llvm::BitCastInst(ptr, llvm::PointerType::get(first->getType(), 0),
"ptr2rvalue_type", callInst);
lCopyMetadata(ptr, callInst);
llvm::Instruction *sinst = new llvm::StoreInst(first, ptr, false,
scatterInfo->align);
lCopyMetadata(sinst, callInst);
llvm::ReplaceInstWithInst(callInst, sinst);
}
modifiedAny = true;
goto restart;
}
}
int step = gatherInfo ? gatherInfo->align : scatterInfo->align;
std::vector<llvm::PHINode *> seenPhis;
if (lVectorIsLinear(offsets, g->target.vectorWidth, step, seenPhis)) {
// We have a linear sequence of memory locations being accessed
// starting with the location given by the offset from
// offsetElements[0], with stride of 4 or 8 bytes (for 32 bit
// and 64 bit gather/scatters, respectively.)
// Get the base pointer using the first guy's offset.
llvm::Value *firstOffset =
llvm::ExtractElementInst::Create(offsets, LLVMInt32(0), "first_offset",
callInst);
llvm::Value *indices[1] = { firstOffset };
#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
llvm::ArrayRef<llvm::Value *> arrayRef(&indices[0], &indices[1]);
llvm::Value *ptr =
llvm::GetElementPtrInst::Create(base, arrayRef, "ptr", callInst);
#else
llvm::Value *ptr =
llvm::GetElementPtrInst::Create(base, &indices[0], &indices[1],
"ptr", callInst);
#endif
lCopyMetadata(ptr, callInst);
if (gatherInfo != NULL) {
Debug(pos, "Transformed gather to unaligned vector load!");
llvm::Value *args[2] = { ptr, mask };
#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
llvm::ArrayRef<llvm::Value *> argArray(&args[0], &args[2]);
llvm::Instruction *newCall =
llvm::CallInst::Create(gatherInfo->loadMaskedFunc, argArray,
"load_masked", (llvm::Instruction *)NULL);
#else
llvm::Instruction *newCall =
llvm::CallInst::Create(gatherInfo->loadMaskedFunc, &args[0],
&args[2], "load_masked");
#endif
lCopyMetadata(newCall, callInst);
llvm::ReplaceInstWithInst(callInst, newCall);
}
else {
Debug(pos, "Transformed scatter to unaligned vector store!");
llvm::Value *rvalue = callInst->getArgOperand(2);
ptr = new llvm::BitCastInst(ptr, scatterInfo->vecPtrType, "ptrcast",
callInst);
llvm::Value *args[3] = { ptr, rvalue, mask };
#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
llvm::ArrayRef<llvm::Value *> argArray(&args[0], &args[3]);
llvm::Instruction *newCall =
llvm::CallInst::Create(scatterInfo->maskedStoreFunc, argArray,
"", (llvm::Instruction *)NULL);
#else
llvm::Instruction *newCall =
llvm::CallInst::Create(scatterInfo->maskedStoreFunc,
&args[0], &args[3], "");
#endif
lCopyMetadata(newCall, callInst);
llvm::ReplaceInstWithInst(callInst, newCall);
}
modifiedAny = true;
goto restart;
}
}
return modifiedAny;
}
static llvm::Pass *
CreateGatherScatterImprovementsPass() {
return new GSImprovementsPass;
}
///////////////////////////////////////////////////////////////////////////
// LowerGSPass
/** For any gathers and scatters remaining after the GSImprovementsPass
runs, we need to turn them into actual native gathers and scatters.
This task is handled by the LowerGSPass here.
*/
class LowerGSPass : public llvm::BasicBlockPass {
public:
static char ID;
LowerGSPass() : BasicBlockPass(ID) { }
const char *getPassName() const { return "Gather/Scatter Improvements"; }
bool runOnBasicBlock(llvm::BasicBlock &BB);
};
char LowerGSPass::ID = 0;
llvm::RegisterPass<LowerGSPass> lgs("lower-gs",
"Lower Gather/Scatter Pass");
struct LowerGSInfo {
LowerGSInfo(const char *pName, const char *aName, bool ig)
: isGather(ig) {
pseudoFunc = m->module->getFunction(pName);
actualFunc = m->module->getFunction(aName);
assert(pseudoFunc != NULL && actualFunc != NULL);
}
llvm::Function *pseudoFunc;
llvm::Function *actualFunc;
const bool isGather;
};
bool
LowerGSPass::runOnBasicBlock(llvm::BasicBlock &bb) {
LowerGSInfo lgsInfo[] = {
LowerGSInfo("__pseudo_gather_base_offsets32_8", "__gather_base_offsets32_i8", true),
LowerGSInfo("__pseudo_gather_base_offsets32_16", "__gather_base_offsets32_i16", true),
LowerGSInfo("__pseudo_gather_base_offsets32_32", "__gather_base_offsets32_i32", true),
LowerGSInfo("__pseudo_gather_base_offsets32_64", "__gather_base_offsets32_i64", true),
LowerGSInfo("__pseudo_gather_base_offsets64_8", "__gather_base_offsets64_i8", true),
LowerGSInfo("__pseudo_gather_base_offsets64_16", "__gather_base_offsets64_i16", true),
LowerGSInfo("__pseudo_gather_base_offsets64_32", "__gather_base_offsets64_i32", true),
LowerGSInfo("__pseudo_gather_base_offsets64_64", "__gather_base_offsets64_i64", true),
LowerGSInfo("__pseudo_gather32_8", "__gather32_i8", true),
LowerGSInfo("__pseudo_gather32_16", "__gather32_i16", true),
LowerGSInfo("__pseudo_gather32_32", "__gather32_i32", true),
LowerGSInfo("__pseudo_gather32_64", "__gather32_i64", true),
LowerGSInfo("__pseudo_gather64_8", "__gather64_i8", true),
LowerGSInfo("__pseudo_gather64_16", "__gather64_i16", true),
LowerGSInfo("__pseudo_gather64_32", "__gather64_i32", true),
LowerGSInfo("__pseudo_gather64_64", "__gather64_i64", true),
LowerGSInfo("__pseudo_scatter_base_offsets32_8", "__scatter_base_offsets32_i8", false),
LowerGSInfo("__pseudo_scatter_base_offsets32_16", "__scatter_base_offsets32_i16", false),
LowerGSInfo("__pseudo_scatter_base_offsets32_32", "__scatter_base_offsets32_i32", false),
LowerGSInfo("__pseudo_scatter_base_offsets32_64", "__scatter_base_offsets32_i64", false),
LowerGSInfo("__pseudo_scatter_base_offsets64_8", "__scatter_base_offsets64_i8", false),
LowerGSInfo("__pseudo_scatter_base_offsets64_16", "__scatter_base_offsets64_i16", false),
LowerGSInfo("__pseudo_scatter_base_offsets64_32", "__scatter_base_offsets64_i32", false),
LowerGSInfo("__pseudo_scatter_base_offsets64_64", "__scatter_base_offsets64_i64", false),
LowerGSInfo("__pseudo_scatter32_8", "__scatter32_i8", false),
LowerGSInfo("__pseudo_scatter32_16", "__scatter32_i16", false),
LowerGSInfo("__pseudo_scatter32_32", "__scatter32_i32", false),
LowerGSInfo("__pseudo_scatter32_64", "__scatter32_i64", false),
LowerGSInfo("__pseudo_scatter64_8", "__scatter64_i8", false),
LowerGSInfo("__pseudo_scatter64_16", "__scatter64_i16", false),
LowerGSInfo("__pseudo_scatter64_32", "__scatter64_i32", false),
LowerGSInfo("__pseudo_scatter64_64", "__scatter64_i64", false),
};
bool modifiedAny = false;
restart:
for (llvm::BasicBlock::iterator iter = bb.begin(), e = bb.end(); iter != e; ++iter) {
// Loop over the instructions and find calls to the
// __pseudo_*_base_offsets_* functions.
llvm::CallInst *callInst = llvm::dyn_cast<llvm::CallInst>(&*iter);
if (callInst == NULL)
continue;
llvm::Function *calledFunc = callInst->getCalledFunction();
LowerGSInfo *info = NULL;
for (unsigned int i = 0; i < sizeof(lgsInfo) / sizeof(lgsInfo[0]); ++i) {
if (lgsInfo[i].pseudoFunc != NULL &&
calledFunc == lgsInfo[i].pseudoFunc) {
info = &lgsInfo[i];
break;
}
}
if (info == NULL)
continue;
// Get the source position from the metadata attached to the call
// instruction so that we can issue PerformanceWarning()s below.
SourcePos pos;
bool ok = lGetSourcePosFromMetadata(callInst, &pos);
assert(ok);
callInst->setCalledFunction(info->actualFunc);
if (info->isGather)
PerformanceWarning(pos, "Gather required to compute value in expression.");
else
PerformanceWarning(pos, "Scatter required for storing value.");
modifiedAny = true;
goto restart;
}
return modifiedAny;
}
static llvm::Pass *
CreateLowerGatherScatterPass() {
return new LowerGSPass;
}
///////////////////////////////////////////////////////////////////////////
// IsCompileTimeConstantPass
/** LLVM IR implementations of target-specific functions may include calls
to the functions "bool __is_compile_time_constant_*(...)"; these allow
them to have specialied code paths for where the corresponding value is
known at compile time. For masks, for example, this allows them to not
incur the cost of a MOVMSK call at runtime to compute its value in
cases where the mask value isn't known until runtime.
This pass resolves these calls into either 'true' or 'false' values so
that later optimization passes can operate with these as constants.
See stdlib.m4 for a number of uses of this idiom.
*/
class IsCompileTimeConstantPass : public llvm::BasicBlockPass {
public:
static char ID;
IsCompileTimeConstantPass(bool last = false) : BasicBlockPass(ID) {
isLastTry = last;
}
const char *getPassName() const { return "Resolve \"is compile time constant\""; }
bool runOnBasicBlock(llvm::BasicBlock &BB);
bool isLastTry;
};
char IsCompileTimeConstantPass::ID = 0;
llvm::RegisterPass<IsCompileTimeConstantPass>
ctcrp("compile-time-constant", "Compile-Time Constant Resolve Pass");
bool
IsCompileTimeConstantPass::runOnBasicBlock(llvm::BasicBlock &bb) {
llvm::Function *funcs[] = {
m->module->getFunction("__is_compile_time_constant_mask"),
m->module->getFunction("__is_compile_time_constant_uniform_int32"),
m->module->getFunction("__is_compile_time_constant_varying_int32")
};
bool modifiedAny = false;
restart:
for (llvm::BasicBlock::iterator i = bb.begin(), e = bb.end(); i != e; ++i) {
// Iterate through the instructions looking for calls to the
// __is_compile_time_constant_*() functions
llvm::CallInst *callInst = llvm::dyn_cast<llvm::CallInst>(&*i);
if (callInst == NULL)
continue;
int j;
int nFuncs = sizeof(funcs) / sizeof(funcs[0]);
for (j = 0; j < nFuncs; ++j) {
if (funcs[j] != NULL && callInst->getCalledFunction() == funcs[j])
break;
}
if (j == nFuncs)
// not a __is_compile_time_constant_* function
continue;
// This optimization pass can be disabled with the (poorly named)
// disableGatherScatterFlattening option.
if (g->opt.disableGatherScatterFlattening) {
llvm::ReplaceInstWithValue(i->getParent()->getInstList(), i, LLVMFalse);
modifiedAny = true;
goto restart;
}
// Is it a constant? Bingo, turn the call's value into a constant
// true value.
llvm::Value *operand = callInst->getArgOperand(0);
if (llvm::isa<llvm::Constant>(operand)) {
llvm::ReplaceInstWithValue(i->getParent()->getInstList(), i, LLVMTrue);
modifiedAny = true;
goto restart;
}
// This pass runs multiple times during optimization. Up until the
// very last time, it only replaces the call with a 'true' if the
// value is known to be constant and otherwise leaves the call
// alone, in case further optimization passes can help resolve its
// value. The last time through, it eventually has to give up, and
// replaces any remaining ones with 'false' constants.
if (isLastTry) {
llvm::ReplaceInstWithValue(i->getParent()->getInstList(), i, LLVMFalse);
modifiedAny = true;
goto restart;
}
}
return modifiedAny;
}
static llvm::Pass *
CreateIsCompileTimeConstantPass(bool isLastTry) {
return new IsCompileTimeConstantPass(isLastTry);
}
///////////////////////////////////////////////////////////////////////////
// MakeInternalFuncsStaticPass
/** There are a number of target-specific functions that we use during
these optimization passes. By the time we are done with optimization,
any uses of these should be inlined and no calls to these functions
should remain. This pass marks all of these functions as having
private linkage so that subsequent passes can eliminate them as dead
code, thus cleaning up the final code output by the compiler. We can't
just declare these as static from the start, however, since then they
end up being eliminated as dead code during early optimization passes
even though we may need to generate calls to them during later
optimization passes.
*/
class MakeInternalFuncsStaticPass : public llvm::ModulePass {
public:
static char ID;
MakeInternalFuncsStaticPass(bool last = false) : ModulePass(ID) {
}
const char *getPassName() const { return "Make internal funcs \"static\""; }
bool runOnModule(llvm::Module &m);
};
char MakeInternalFuncsStaticPass::ID = 0;
llvm::RegisterPass<MakeInternalFuncsStaticPass>
mifsp("make-internal-funcs-static", "Make Internal Funcs Static Pass");
bool
MakeInternalFuncsStaticPass::runOnModule(llvm::Module &module) {
const char *names[] = {
"__fast_masked_vload",
"__gather_base_offsets32_i8", "__gather_base_offsets32_i16",
"__gather_base_offsets32_i32", "__gather_base_offsets32_i64",
"__gather_base_offsets64_i8", "__gather_base_offsets64_i16",
"__gather_base_offsets64_i32", "__gather_base_offsets64_i64",
"__gather32_i8", "__gather32_i16",
"__gather32_i32", "__gather32_i64",
"__gather64_i8", "__gather64_i16",
"__gather64_i32", "__gather64_i64",
"__gather_elt32_i8", "__gather_elt32_i16",
"__gather_elt32_i32", "__gather_elt32_i64",
"__gather_elt64_i8", "__gather_elt64_i16",
"__gather_elt64_i32", "__gather_elt64_i64",
"__load_and_broadcast_8", "__load_and_broadcast_16",
"__load_and_broadcast_32", "__load_and_broadcast_64",
"__load_masked_8", "__load_masked_16",
"__load_masked_32", "__load_masked_64",
"__masked_store_8", "__masked_store_16",
"__masked_store_32", "__masked_store_64",
"__masked_store_blend_8", "__masked_store_blend_16",
"__masked_store_blend_32", "__masked_store_blend_64",
"__scatter_base_offsets32_i8", "__scatter_base_offsets32_i16",
"__scatter_base_offsets32_i32", "__scatter_base_offsets32_i64",
"__scatter_base_offsets64_i8", "__scatter_base_offsets64_i16",
"__scatter_base_offsets64_i32", "__scatter_base_offsets64_i64",
"__scatter_elt32_i8", "__scatter_elt32_i16",
"__scatter_elt32_i32", "__scatter_elt32_i64",
"__scatter_elt64_i8", "__scatter_elt64_i16",
"__scatter_elt64_i32", "__scatter_elt64_i64",
"__scatter32_i8", "__scatter32_i16",
"__scatter32_i32", "__scatter32_i64",
"__scatter64_i8", "__scatter64_i16",
"__scatter64_i32", "__scatter64_i64",
};
bool modifiedAny = false;
int count = sizeof(names) / sizeof(names[0]);
for (int i = 0; i < count; ++i) {
llvm::Function *f = m->module->getFunction(names[i]);
if (f != NULL) {
f->setLinkage(llvm::GlobalValue::InternalLinkage);
modifiedAny = true;
}
}
return modifiedAny;
}
static llvm::Pass *
CreateMakeInternalFuncsStaticPass() {
return new MakeInternalFuncsStaticPass;
}
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