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Revert "r214897 - Remove dead zero store to calloc initialized memory" 

It broke msan.

llvm-svn: 214989
This commit is contained in:
Rui Ueyama 2014-08-06 19:30:38 +00:00
parent b5217507c7
commit c487f7728e
2 changed files with 15 additions and 52 deletions
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50
llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
View File

@ -514,49 +514,29 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
if (!InstDep.isDef() && !InstDep.isClobber())
continue;
// Check for cases where the store is redundant.
// If we're storing the same value back to a pointer that we just
// loaded from, then the store can be removed.
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
bool DeleteStore = false;
// If we're storing the same value back to a pointer that we just
// loaded from, then the store can be removed.
if (LoadInst *DepLoad = dyn_cast<LoadInst>(InstDep.getInst())) {
if (SI->getPointerOperand() == DepLoad->getPointerOperand() &&
SI->getOperand(0) == DepLoad && isRemovable(SI)) {
DEBUG(dbgs() << "DSE: Remove Store Of Load from same pointer:\n "
<< "LOAD: " << *DepLoad << "\n STORE: " << *SI << '\n');
DeleteStore = true;
}
}
// If we find a store to memory which was defined by calloc
// we can remove the store if the value being stored is a
// constant zero (since calloc initialized the memory to
// that same value) or the store is undefined (if out of
// bounds).
if (isCallocLikeFn(InstDep.getInst(), TLI) && isRemovable(SI)) {
Value *V = SI->getValueOperand();
if (isa<Constant>(V) && cast<Constant>(V)->isNullValue()) {
DEBUG(dbgs() << "DSE: Remove Store Of Zero to Calloc:\n "
<< "CALLOC: " << *InstDep.getInst() << "\n"
<< "STORE: " << *SI << '\n');
DeleteStore = true;
}
}
// DeleteDeadInstruction can delete the current instruction. Save BBI
// in case we need it.
WeakVH NextInst(BBI);
if (DeleteStore) {
// DeleteDeadInstruction can delete the current instruction. Save BBI
// in case we need it.
WeakVH NextInst(BBI);
DeleteDeadInstruction(SI, *MD, TLI);
if (!NextInst) // Next instruction deleted.
BBI = BB.begin();
else if (BBI != BB.begin()) // Revisit this instruction if possible.
--BBI;
++NumFastStores;
MadeChange = true;
continue;
DeleteDeadInstruction(SI, *MD, TLI);
if (!NextInst) // Next instruction deleted.
BBI = BB.begin();
else if (BBI != BB.begin()) // Revisit this instruction if possible.
--BBI;
++NumFastStores;
MadeChange = true;
continue;
}
}
}

17
llvm/test/Transforms/DeadStoreElimination/calloc-store.ll
View File

@ -1,17 +0,0 @@
; RUN: opt < %s -basicaa -dse -S | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
; Function Attrs: nounwind
declare noalias i8* @calloc(i64, i64)
; Function Attrs: nounwind uwtable
define noalias i32* @test_store() {
; CHECK-LABEL: test_store
%1 = tail call noalias i8* @calloc(i64 1, i64 4)
%2 = bitcast i8* %1 to i32*
; This store is dead and should be removed
store i32 0, i32* %2, align 4
; CHECK-NOT: store i32 0, i32* %2, align 4
ret i32* %2
}