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Handle more forms of constant vectors in lGetMask().

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Various optimization passes depend on turning a compile-time constant
mask into a bit vector; it turns out that in LLVM3.1, constant vectors
of ints/floats are represented with llvM::ConstantDataVector, but
constant vectors of bools use llvm::ConstantVector (which is what LLVM
3.0 uses for all constant vectors).  Now lGetMask() always does the
llvm::ConstantVector path, to cover this case.

This improves generated C++ code by eliminating things like select
with an all on/off mask, turning movmask calls with constants into
constant values, etc.
This commit is contained in:
Matt Pharr
2012-04-18 11:34:28 -07:00
parent c202e9e106
commit 7c91b01125
1 changed files with 55 additions and 32 deletions
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87
opt.cpp
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@@ -586,6 +586,40 @@ IntrinsicsOpt::IntrinsicsOpt()
}
/** Given a vector of constant values (int, float, or bool) representing an
execution mask, convert it to a bitvector where the 0th bit corresponds
to the first vector value and so forth.
*/
static int
lConstElementsToMask(const llvm::SmallVector<llvm::Constant *,
ISPC_MAX_NVEC> &elements) {
Assert(elements.size() <= 32);
int mask = 0;
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 != NULL) {
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;
}
/** 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.
@@ -600,41 +634,30 @@ lGetMask(llvm::Value *factor) {
Assert(g->target.vectorWidth < 32);
#ifdef LLVM_3_1svn
llvm::ConstantDataVector *cv = llvm::dyn_cast<llvm::ConstantDataVector>(factor);
#else
llvm::ConstantVector *cv = llvm::dyn_cast<llvm::ConstantVector>(factor);
#endif
if (cv) {
int mask = 0;
llvm::ConstantDataVector *cdv = llvm::dyn_cast<llvm::ConstantDataVector>(factor);
if (cdv != NULL) {
llvm::SmallVector<llvm::Constant *, ISPC_MAX_NVEC> elements;
#ifdef LLVM_3_1svn
for (int i = 0; i < (int)cv->getNumElements(); ++i)
elements.push_back(cv->getElementAsConstant(i));
for (int i = 0; i < (int)cdv->getNumElements(); ++i)
elements.push_back(cdv->getElementAsConstant(i));
return lConstElementsToMask(elements);
}
#endif
llvm::ConstantVector *cv = llvm::dyn_cast<llvm::ConstantVector>(factor);
if (cv != NULL) {
llvm::SmallVector<llvm::Constant *, ISPC_MAX_NVEC> elements;
#ifdef LLVM_3_1svn
for (int i = 0; i < (int)cv->getNumOperands(); ++i) {
llvm::Constant *c =
llvm::dyn_cast<llvm::Constant>(cv->getOperand(i));
if (c == NULL)
return NULL;
elements.push_back(c);
}
#else
cv->getVectorElements(elements);
#endif
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;
return lConstElementsToMask(elements);
}
else if (llvm::isa<llvm::ConstantAggregateZero>(factor))
return 0;
@@ -1149,7 +1172,7 @@ lGetBasePtrAndOffsets(llvm::Value *ptrs, llvm::Value **offsets,
// Indexing into global arrays can lead to this form, with
// ConstantVectors..
llvm::SmallVector<llvm::Constant *, ISPC_MAX_NVEC> elements;
#ifdef LLVM_3_1svn
#ifdef LLVM_3_1svn
for (int i = 0; i < (int)cv->getNumOperands(); ++i) {
llvm::Constant *c =
llvm::dyn_cast<llvm::Constant>(cv->getOperand(i));