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Create an explicit copy for byval parameters even
when inlining a readonly function. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46393 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -240,12 +240,15 @@ bool llvm::InlineFunction(CallSite CS, CallGraph *CG, const TargetData *TD) {
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E = CalledFunc->arg_end(); I != E; ++I, ++AI, ++ArgNo) {
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Value *ActualArg = *AI;
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// When byval arguments actually inlined, we need to make the copy implied
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// by them explicit. However, we don't do this if the callee is readonly
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// or readnone, because the copy would be unneeded: the callee doesn't
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// modify the struct.
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if (CalledFunc->paramHasAttr(ArgNo+1, ParamAttr::ByVal) &&
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!CalledFunc->onlyReadsMemory()) {
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// When byval arguments are inlined, we need to make the copy implied
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// by them explicit. It is tempting to think that this is not needed if
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// the callee is readonly, because the callee doesn't modify the struct.
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// However this would be wrong: readonly means that any writes the callee
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// performs are not visible to the caller. But writes by the callee to
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// an argument passed byval are by definition not visible to the caller!
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// Since we allow this kind of readonly function, there needs to be an
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// explicit copy in order to keep the writes invisible after inlining.
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if (CalledFunc->paramHasAttr(ArgNo+1, ParamAttr::ByVal)) {
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const Type *AggTy = cast<PointerType>(I->getType())->getElementType();
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const Type *VoidPtrTy = PointerType::getUnqual(Type::Int8Ty);
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19
test/CFrontend/2008-01-26-ReadOnlyByVal.c
Normal file
19
test/CFrontend/2008-01-26-ReadOnlyByVal.c
Normal file
@ -0,0 +1,19 @@
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// RUN: %llvmgcc %s -S -O1 -o - | llvm-as | opt -std-compile-opts | llvm-dis | not grep add
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struct S { int A; int B; int C; int D; };
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int f(struct S x) __attribute__ ((const));
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static int __attribute__ ((const)) g(struct S x) {
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x.A = x.B;
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return f(x);
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}
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int h(void) {
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struct S x;
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int r;
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x.A = 0;
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x.B = 9;
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r = g(x);
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return r + x.A;
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}
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