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Add --opt=force-aligned-memory option.

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This forces all vector loads/stores to be done assuming that the given
pointer is aligned to the vector size, thus allowing the use of sometimes
more-efficient instructions.  (If it isn't the case that the memory is
aligned, the program will fail!).
This commit is contained in:
Matt Pharr
2012-09-14 13:49:45 -07:00
parent 59b0a2b208
commit be2108260e
6 changed files with 35 additions and 8 deletions
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17
opt.cpp
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@@ -791,7 +791,11 @@ IntrinsicsOpt::runOnBasicBlock(llvm::BasicBlock &bb) {
llvm::PointerType::get(returnType, 0),
name, callInst);
lCopyMetadata(castPtr, callInst);
int align = callInst->getCalledFunction() == avxMaskedLoad32 ? 4 : 8;
int align;
if (g->opt.forceAlignedMemory)
align = 0;
else
align = callInst->getCalledFunction() == avxMaskedLoad32 ? 4 : 8;
name = LLVMGetName(callInst->getArgOperand(0), "_load");
llvm::Instruction *loadInst =
new llvm::LoadInst(castPtr, name, false /* not volatile */,
@@ -829,7 +833,11 @@ IntrinsicsOpt::runOnBasicBlock(llvm::BasicBlock &bb) {
llvm::StoreInst *storeInst =
new llvm::StoreInst(rvalue, castPtr, (llvm::Instruction *)NULL);
int align = callInst->getCalledFunction() == avxMaskedStore32 ? 4 : 8;
int align;
if (g->opt.forceAlignedMemory)
align = 0;
else
align = callInst->getCalledFunction() == avxMaskedStore32 ? 4 : 8;
storeInst->setAlignment(align);
lCopyMetadata(storeInst, callInst);
llvm::ReplaceInstWithInst(callInst, storeInst);
@@ -2553,7 +2561,7 @@ lImproveMaskedStore(llvm::CallInst *callInst) {
lCopyMetadata(lvalue, callInst);
llvm::Instruction *store =
new llvm::StoreInst(rvalue, lvalue, false /* not volatile */,
info->align);
g->opt.forceAlignedMemory ? 0 : info->align);
lCopyMetadata(store, callInst);
llvm::ReplaceInstWithInst(callInst, store);
return true;
@@ -2616,7 +2624,8 @@ lImproveMaskedLoad(llvm::CallInst *callInst,
callInst);
llvm::Instruction *load =
new llvm::LoadInst(ptr, callInst->getName(), false /* not volatile */,
info->align, (llvm::Instruction *)NULL);
g->opt.forceAlignedMemory ? 0 : info->align,
(llvm::Instruction *)NULL);
lCopyMetadata(load, callInst);
llvm::ReplaceInstWithInst(callInst, load);
return true;