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Duncan deftly points out that readnone functions aren't

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invalidated by stores, so they can be handled as 'simple'
operations.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122785 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2011-01-03 23:38:13 +00:00
parent 7158e08b8e
commit e508dd4c75
2 changed files with 18 additions and 1 deletions
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6
lib/Transforms/Scalar/EarlyCSE.cpp
View File

@ -56,6 +56,9 @@ namespace {
}
static bool canHandle(Instruction *Inst) {
// This can only handle non-void readnone functions.
if (CallInst *CI = dyn_cast<CallInst>(Inst))
return CI->doesNotAccessMemory() && !CI->getType()->isVoidTy();
return isa<CastInst>(Inst) || isa<BinaryOperator>(Inst) ||
isa<GetElementPtrInst>(Inst) || isa<CmpInst>(Inst) ||
isa<SelectInst>(Inst) || isa<ExtractElementInst>(Inst) ||
@ -105,7 +108,8 @@ unsigned DenseMapInfo<SimpleValue>::getHashValue(SimpleValue Val) {
Res ^= *I;
} else {
// nothing extra to hash in.
assert((isa<BinaryOperator>(Inst) || isa<GetElementPtrInst>(Inst) ||
assert((isa<CallInst>(Inst) ||
isa<BinaryOperator>(Inst) || isa<GetElementPtrInst>(Inst) ||
isa<SelectInst>(Inst) || isa<ExtractElementInst>(Inst) ||
isa<InsertElementInst>(Inst) || isa<ShuffleVectorInst>(Inst)) &&
"Invalid/unknown instruction");

13
test/Transforms/EarlyCSE/basic.ll
View File

@ -106,3 +106,16 @@ define void @test7(i32 *%P) {
; CHECK-NEXT: store i32 45
; CHECK-NEXT: ret void
}
;; Readnone functions aren't invalidated by stores.
; CHECK: @test8
define i32 @test8(i32 *%P) {
%V1 = call i32 @func(i32* %P) readnone
store i32 4, i32* %P
%V2 = call i32 @func(i32* %P) readnone
%Diff = sub i32 %V1, %V2
ret i32 %Diff
; CHECK: ret i32 0
}