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fix instcombine to only do store sinking when the alignments

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of the two loads agree.  Propagate that onto the new store.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85772 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2009-11-02 02:06:37 +00:00
parent f013eea972
commit 7ebbabf500
2 changed files with 26 additions and 4 deletions
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12
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@@ -11943,9 +11943,11 @@ bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
return false; return false;
--BBI; --BBI;
} }
// If this isn't a store, or isn't a store to the same location, bail out. // If this isn't a store, isn't a store to the same location, or if the
// alignments differ, bail out.
OtherStore = dyn_cast<StoreInst>(BBI); OtherStore = dyn_cast<StoreInst>(BBI);
if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1)) if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1) ||
OtherStore->getAlignment() != SI.getAlignment())
return false; return false;
} else { } else {
// Otherwise, the other block ended with a conditional branch. If one of the // Otherwise, the other block ended with a conditional branch. If one of the
@@ -11960,7 +11962,8 @@ bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
for (;; --BBI) { for (;; --BBI) {
// Check to see if we find the matching store. // Check to see if we find the matching store.
if ((OtherStore = dyn_cast<StoreInst>(BBI))) { if ((OtherStore = dyn_cast<StoreInst>(BBI))) {
if (OtherStore->getOperand(1) != SI.getOperand(1)) if (OtherStore->getOperand(1) != SI.getOperand(1) ||
OtherStore->getAlignment() != SI.getAlignment())
return false; return false;
break; break;
} }
@@ -11995,7 +11998,8 @@ bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
// insert it. // insert it.
BBI = DestBB->getFirstNonPHI(); BBI = DestBB->getFirstNonPHI();
InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1), InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
OtherStore->isVolatile()), *BBI); OtherStore->isVolatile(),
SI.getAlignment()), *BBI);
// Nuke the old stores. // Nuke the old stores.
EraseInstFromFunction(SI); EraseInstFromFunction(SI);

18
test/Transforms/InstCombine/store.ll
View File

@@ -64,3 +64,21 @@ Cont:
; CHECK-NEXT: ret i32 %storemerge ; CHECK-NEXT: ret i32 %storemerge
} }
; "if then"
define void @test5(i1 %C, i32* %P) {
store i32 47, i32* %P, align 1
br i1 %C, label %Cond, label %Cont
Cond:
store i32 -987654321, i32* %P, align 1
br label %Cont
Cont:
ret void
; CHECK: @test5
; CHECK: Cont:
; CHECK-NEXT: %storemerge = phi i32
; CHECK-NEXT: store i32 %storemerge, i32* %P, align 1
; CHECK-NEXT: ret void
}