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Broadcast implementation as InsertElement+Shuffle and related improvements

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This commit is contained in:
Dmitry Babokin
2013-04-10 02:18:24 +04:00
parent 603abf70dc
commit 5898532605
6 changed files with 153 additions and 56 deletions
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74
ctx.cpp
View File

@@ -1379,6 +1379,19 @@ FunctionEmitContext::MasksAllEqual(llvm::Value *v1, llvm::Value *v2) {
#endif
}
llvm::Value *
FunctionEmitContext::ProgramIndex() {
llvm::SmallVector<llvm::Constant*, 16> array;
for (int i = 0; i < g->target->getVectorWidth() ; ++i) {
llvm::Constant *C = LLVMInt32(i);
array.push_back(C);
}
llvm::Constant* index = llvm::ConstantVector::get(array);
return index;
}
llvm::Value *
FunctionEmitContext::GetStringPtr(const std::string &str) {
@@ -1729,26 +1742,48 @@ FunctionEmitContext::SmearUniform(llvm::Value *value, const char *name) {
llvm::Value *ret = NULL;
llvm::Type *eltType = value->getType();
llvm::Type *vecType = NULL;
llvm::PointerType *pt =
llvm::dyn_cast<llvm::PointerType>(eltType);
if (pt != NULL) {
// Varying pointers are represented as vectors of i32/i64s
ret = llvm::UndefValue::get(LLVMTypes::VoidPointerVectorType);
vecType = LLVMTypes::VoidPointerVectorType;
value = PtrToIntInst(value);
}
else
else {
// All other varying types are represented as vectors of the
// underlying type.
ret = llvm::UndefValue::get(llvm::VectorType::get(eltType,
g->target->getVectorWidth()));
for (int i = 0; i < g->target->getVectorWidth(); ++i) {
llvm::Twine n = llvm::Twine("smear.") + llvm::Twine(name ? name : "") +
llvm::Twine(i);
ret = InsertInst(ret, value, i, n.str().c_str());
vecType = llvm::VectorType::get(eltType, g->target->getVectorWidth());
}
// Check for a constant case.
if (llvm::Constant *const_val = llvm::dyn_cast<llvm::Constant>(value)) {
ret = llvm::ConstantVector::getSplat(
g->target->getVectorWidth(),
const_val);
return ret;
}
// Generate the follwoing sequence:
// %broadcast_init.0 = insertelement <4 x i32> undef, i32 %val, i32 0
// %broadcast.1 = shufflevector <4 x i32> %smear.0, <4 x i32> undef,
// <4 x i32> zeroinitializer
//
llvm::Value *undef1 = llvm::UndefValue::get(vecType);
llvm::Value *undef2 = llvm::UndefValue::get(vecType);
// InsertElement
llvm::Twine tw1 = llvm::Twine("broadcast_init.") + llvm::Twine(name ? name : "");
llvm::Value *insert = InsertInst(undef1, value, 0, tw1.str().c_str());
// ShuffleVector
llvm::Constant *zeroVec = llvm::ConstantVector::getSplat(
g->target->getVectorWidth(),
llvm::Constant::getNullValue(llvm::Type::getInt32Ty(*g->ctx)));
llvm::Twine tw2 = llvm::Twine("broadcast.") + llvm::Twine(name ? name : "");
ret = ShuffleInst(insert, undef2, zeroVec, tw2.str().c_str());
return ret;
}
@@ -3131,6 +3166,27 @@ FunctionEmitContext::InsertInst(llvm::Value *v, llvm::Value *eltVal, int elt,
}
llvm::Value *
FunctionEmitContext::ShuffleInst(llvm::Value *v1, llvm::Value *v2, llvm::Value *mask,
const char *name) {
if (v1 == NULL || v2 == NULL || mask == NULL) {
AssertPos(currentPos, m->errorCount > 0);
return NULL;
}
if (name == NULL) {
char buf[32];
sprintf(buf, "_shuffle");
name = LLVMGetName(v1, buf);
}
llvm::Instruction *ii = new llvm::ShuffleVectorInst(v1, v2, mask, name, bblock);
AddDebugPos(ii);
return ii;
}
llvm::PHINode *
FunctionEmitContext::PhiNode(llvm::Type *type, int count,
const char *name) {

7
ctx.h
View File

@@ -295,6 +295,10 @@ public:
that indicates whether the two masks are equal. */
llvm::Value *MasksAllEqual(llvm::Value *mask1, llvm::Value *mask2);
/** Generate ConstantVector, which contains ProgramIndex, i.e.
< i32 0, i32 1, i32 2, i32 3> */
llvm::Value *ProgramIndex();
/** Given a string, create an anonymous global variable to hold its
value and return the pointer to the string. */
llvm::Value *GetStringPtr(const std::string &str);
@@ -500,6 +504,9 @@ public:
llvm::Value *InsertInst(llvm::Value *v, llvm::Value *eltVal, int elt,
const char *name = NULL);
llvm::Value *ShuffleInst(llvm::Value *v1, llvm::Value *v2, llvm::Value *mask,
const char *name = NULL);
llvm::PHINode *PhiNode(llvm::Type *type, int count,
const char *name = NULL);
llvm::Instruction *SelectInst(llvm::Value *test, llvm::Value *val0,

48
llvmutil.cpp
View File

@@ -601,11 +601,15 @@ lGetIntValue(llvm::Value *offset) {
void
LLVMFlattenInsertChain(llvm::InsertElementInst *ie, int vectorWidth,
LLVMFlattenInsertChain(llvm::Value *inst, int vectorWidth,
llvm::Value **elements) {
for (int i = 0; i < vectorWidth; ++i)
for (int i = 0; i < vectorWidth; ++i) {
elements[i] = NULL;
}
// Catch a pattern of InsertElement chain.
if (llvm::InsertElementInst *ie =
llvm::dyn_cast<llvm::InsertElementInst>(inst)) {
while (ie != NULL) {
int64_t iOffset = lGetIntValue(ie->getOperand(2));
Assert(iOffset >= 0 && iOffset < vectorWidth);
@@ -618,8 +622,9 @@ LLVMFlattenInsertChain(llvm::InsertElementInst *ie, int vectorWidth,
llvm::Value *insertBase = ie->getOperand(0);
ie = llvm::dyn_cast<llvm::InsertElementInst>(insertBase);
if (ie == NULL) {
if (llvm::isa<llvm::UndefValue>(insertBase))
if (llvm::isa<llvm::UndefValue>(insertBase)) {
return;
}
// Get the value out of a constant vector if that's what we
// have
@@ -642,6 +647,31 @@ LLVMFlattenInsertChain(llvm::InsertElementInst *ie, int vectorWidth,
}
}
}
// Catch a pattern of broadcast implemented as InsertElement + Shuffle:
// %broadcast_init.0 = insertelement <4 x i32> undef, i32 %val, i32 0
// %broadcast.1 = shufflevector <4 x i32> %smear.0, <4 x i32> undef,
// <4 x i32> zeroinitializer
else if (llvm::ShuffleVectorInst *shuf =
llvm::dyn_cast<llvm::ShuffleVectorInst>(inst)) {
llvm::Value *indices = shuf->getOperand(2);
if (llvm::isa<llvm::ConstantAggregateZero>(indices)) {
llvm::Value *op = shuf->getOperand(0);
llvm::InsertElementInst *ie = llvm::dyn_cast<llvm::InsertElementInst>(op);
if (ie != NULL &&
llvm::isa<llvm::UndefValue>(ie->getOperand(0))) {
llvm::ConstantInt *ci =
llvm::dyn_cast<llvm::ConstantInt>(ie->getOperand(2));
if (ci->isZero()) {
for (int i = 0; i < vectorWidth; ++i) {
elements[i] = ie->getOperand(1);
}
return;
}
}
}
}
}
bool
@@ -694,10 +724,10 @@ lIsExactMultiple(llvm::Value *val, int baseValue, int vectorLength,
else
Assert(LLVMVectorValuesAllEqual(val));
llvm::InsertElementInst *ie = llvm::dyn_cast<llvm::InsertElementInst>(val);
if (ie != NULL) {
if (llvm::isa<llvm::InsertElementInst>(val) ||
llvm::isa<llvm::ShuffleVectorInst>(val)) {
llvm::Value *elts[ISPC_MAX_NVEC];
LLVMFlattenInsertChain(ie, g->target->getVectorWidth(), elts);
LLVMFlattenInsertChain(val, g->target->getVectorWidth(), elts);
// We just need to check the scalar first value, since we know that
// all elements are equal
return lIsExactMultiple(elts[0], baseValue, vectorLength,
@@ -1440,10 +1470,10 @@ lExtractFirstVectorElement(llvm::Value *v,
// If we have a chain of insertelement instructions, then we can just
// flatten them out and grab the value for the first one.
llvm::InsertElementInst *ie = llvm::dyn_cast<llvm::InsertElementInst>(v);
if (ie != NULL) {
if (llvm::isa<llvm::InsertElementInst>(v) ||
llvm::isa<llvm::ShuffleVectorInst>(v)) {
llvm::Value *elements[ISPC_MAX_NVEC];
LLVMFlattenInsertChain(ie, vt->getNumElements(), elements);
LLVMFlattenInsertChain(v, vt->getNumElements(), elements);
return elements[0];
}

7
llvmutil.h
View File

@@ -264,8 +264,13 @@ extern bool LLVMExtractVectorInts(llvm::Value *v, int64_t ret[], int *nElts);
constant vector. For anything more complex (e.g. some other arbitrary
value, it doesn't try to extract element values into the returned
array.
This also handles common broadcast pattern:
%broadcast_init.0 = insertelement <4 x i32> undef, i32 %val, i32 0
%broadcast.1 = shufflevector <4 x i32> %smear.0, <4 x i32> undef,
<4 x i32> zeroinitializer
*/
extern void LLVMFlattenInsertChain(llvm::InsertElementInst *ie, int vectorWidth,
extern void LLVMFlattenInsertChain(llvm::Value *inst, int vectorWidth,
llvm::Value **elements);
/** This is a utility routine for debugging that dumps out the given LLVM

13
opt.cpp
View File

@@ -1058,10 +1058,10 @@ lCheckForActualPointer(llvm::Value *v) {
*/
static llvm::Value *
lGetBasePointer(llvm::Value *v) {
llvm::InsertElementInst *ie = llvm::dyn_cast<llvm::InsertElementInst>(v);
if (ie != NULL) {
if (llvm::isa<llvm::InsertElementInst>(v) ||
llvm::isa<llvm::ShuffleVectorInst>(v)) {
llvm::Value *elements[ISPC_MAX_NVEC];
LLVMFlattenInsertChain(ie, g->target->getVectorWidth(), elements);
LLVMFlattenInsertChain(v, g->target->getVectorWidth(), elements);
// Make sure none of the elements is undefined.
// TODO: it's probably ok to allow undefined elements and return
@@ -1080,9 +1080,12 @@ lGetBasePointer(llvm::Value *v) {
}
// This case comes up with global/static arrays
llvm::ConstantVector *cv = llvm::dyn_cast<llvm::ConstantVector>(v);
if (cv != NULL)
if (llvm::ConstantVector *cv = llvm::dyn_cast<llvm::ConstantVector>(v)) {
return lCheckForActualPointer(cv->getSplatValue());
}
else if (llvm::ConstantDataVector *cdv = llvm::dyn_cast<llvm::ConstantDataVector>(v)) {
return lCheckForActualPointer(cdv->getSplatValue());
}
return NULL;
}

6
stmt.cpp
View File

@@ -1993,11 +1993,7 @@ ForeachActiveStmt::EmitCode(FunctionEmitContext *ctx) const {
// math...)
// Get the "program index" vector value
llvm::Value *programIndex =
llvm::UndefValue::get(LLVMTypes::Int32VectorType);
for (int i = 0; i < g->target->getVectorWidth(); ++i)
programIndex = ctx->InsertInst(programIndex, LLVMInt32(i), i,
"prog_index");
llvm::Value *programIndex = ctx->ProgramIndex();
// And smear the current lane out to a vector
llvm::Value *firstSet32 =