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Constant propagating byval pointer is safe if function is readonly.

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llvm-svn: 82700
This commit is contained in:
Torok Edwin 2009-09-24 18:33:42 +00:00
parent ff8027ced6
commit 193d22fa77
3 changed files with 22 additions and 6 deletions
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2
lib/Transforms/IPO/IPConstantPropagation.cpp
View File

@ -131,7 +131,7 @@ bool IPCP::PropagateConstantsIntoArguments(Function &F) {
for (unsigned i = 0, e = ArgumentConstants.size(); i != e; ++i, ++AI) {
// Do we have a constant argument?
if (ArgumentConstants[i].second || AI->use_empty() ||
(AI->hasByValAttr() && isa<PointerType>(AI->getType())))
(AI->hasByValAttr() && !F.onlyReadsMemory()))
continue;
Value *V = ArgumentConstants[i].first;

2
lib/Transforms/Scalar/SCCP.cpp
View File

@ -1267,7 +1267,7 @@ CallOverdefined:
for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
AI != E; ++AI, ++CAI) {
LatticeVal &IV = ValueState[AI];
if (AI->hasByValAttr() && isa<PointerType>(AI->getType())) {
if (AI->hasByValAttr() && !F->onlyReadsMemory()) {
IV.markOverdefined();
continue;
}

22
test/Transforms/IPConstantProp/2009-09-24-byval-ptr.ll
View File

@ -16,9 +16,25 @@ entry:
return: ; preds = %entry
ret void
}
define void @unions() nounwind {
define internal i32 @vfu2(%struct.MYstr* byval align 4 %u) nounwind readonly {
entry:
call void @vfu1(%struct.MYstr* byval align 4 @mystr) nounwind
ret void
%0 = getelementptr %struct.MYstr* %u, i32 0, i32 1 ; <i32*> [#uses=1]
%1 = load i32* %0
; CHECK: load i32* getelementptr inbounds (%struct.MYstr* @mystr, i32 0, i32 1) ; <i32> [#uses=1]
%2 = getelementptr %struct.MYstr* %u, i32 0, i32 0 ; <i8*> [#uses=1]
%3 = load i8* %2
; CHECK: load i8* getelementptr inbounds (%struct.MYstr* @mystr, i32 0, i32 0) ; <i8> [#uses=1]
%4 = zext i8 %3 to i32
%5 = add i32 %4, %1
ret i32 %5
}
define i32 @unions() nounwind {
entry:
call void @vfu1(%struct.MYstr* byval align 4 @mystr) nounwind
%result = call i32 @vfu2(%struct.MYstr* byval align 4 @mystr) nounwind
ret i32 %result
}