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fix PR8769, a miscompilation by inliner when inlining a function with a byval 

argument.  The generated alloca has to have at least the alignment of the
byval, if not, the client may be making assumptions that the new alloca won't
satisfy.

llvm-svn: 122234
This commit is contained in:
Chris Lattner 2010-12-20 07:45:28 +00:00
parent a9a5c59dd1
commit 7394680a00
2 changed files with 34 additions and 6 deletions
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16
llvm/lib/Transforms/Utils/InlineFunction.cpp
View File

@ -252,7 +252,6 @@ bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI) {
CalledFunc->isDeclaration() || // call, or call to a vararg function!
CalledFunc->getFunctionType()->isVarArg()) return false;
// If the call to the callee is not a tail call, we must clear the 'tail'
// flags on any calls that we inline.
bool MustClearTailCallFlags =
@ -308,14 +307,19 @@ bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI) {
if (CalledFunc->paramHasAttr(ArgNo+1, Attribute::ByVal) &&
!CalledFunc->onlyReadsMemory()) {
const Type *AggTy = cast<PointerType>(I->getType())->getElementType();
const Type *VoidPtrTy =
Type::getInt8PtrTy(Context);
const Type *VoidPtrTy = Type::getInt8PtrTy(Context);
// Create the alloca. If we have TargetData, use nice alignment.
unsigned Align = 1;
if (IFI.TD) Align = IFI.TD->getPrefTypeAlignment(AggTy);
Value *NewAlloca = new AllocaInst(AggTy, 0, Align,
I->getName(),
if (IFI.TD)
Align = IFI.TD->getPrefTypeAlignment(AggTy);
// If the byval had an alignment specified, we *must* use at least that
// alignment, as it is required by the byval argument (and uses of the
// pointer inside the callee).
Align = std::max(Align, CalledFunc->getParamAlignment(ArgNo+1));
Value *NewAlloca = new AllocaInst(AggTy, 0, Align, I->getName(),
&*Caller->begin()->begin());
// Emit a memcpy.
const Type *Tys[3] = {VoidPtrTy, VoidPtrTy, Type::getInt64Ty(Context)};

24
llvm/test/Transforms/Inline/byval.ll
View File

@ -56,3 +56,27 @@ entry:
; CHECK-NOT: call void @llvm.memcpy
; CHECK: ret i32
}
; Inlining a byval with an explicit alignment needs to use *at least* that
; alignment on the generated alloca.
; PR8769
declare void @g3(%struct.ss* %p)
define internal void @f3(%struct.ss* byval align 64 %b) nounwind {
call void @g3(%struct.ss* %b) ;; Could make alignment assumptions!
ret void
}
define void @test3() nounwind {
entry:
%S = alloca %struct.ss, align 1 ;; May not be aligned.
call void @f3( %struct.ss* byval align 64 %S) nounwind
ret void
; CHECK: @test3()
; CHECK: %b = alloca %struct.ss, align 64
; CHECK: %S = alloca %struct.ss
; CHECK: call void @llvm.memcpy
; CHECK: call void @g3(%struct.ss* %b)
; CHECK: ret void
}