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Make DSE potentially more aggressive by being more specific about alloca sizes.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18309 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-11-28 20:44:37 +00:00
parent eaf8f9c667
commit 8305a64dce
1 changed files with 10 additions and 4 deletions
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14
lib/Transforms/Scalar/DeadStoreElimination.cpp
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@ -16,6 +16,7 @@
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Scalar.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/Analysis/AliasAnalysis.h"
@ -63,13 +64,18 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
AliasSetTracker KillLocs(AA);
// If this block ends in a return, unwind, and eventually tailcall/barrier,
// then all allocas are dead at its end.
// If this block ends in a return, unwind, unreachable, and eventually
// tailcall, then all allocas are dead at its end.
if (BB.getTerminator()->getNumSuccessors() == 0) {
BasicBlock *Entry = BB.getParent()->begin();
for (BasicBlock::iterator I = Entry->begin(), E = Entry->end(); I != E; ++I)
if (AllocaInst *AI = dyn_cast<AllocaInst>(I))
KillLocs.add(AI, ~0);
if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
unsigned Size = ~0U;
if (!AI->isArrayAllocation() &&
AI->getType()->getElementType()->isSized())
Size = TD.getTypeSize(AI->getType()->getElementType());
KillLocs.add(AI, Size);
}
}
// PotentiallyDeadInsts - Deleting dead stores from the program can make other