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MergeFunc: Transfer the callee's attributes when replacing a direct caller

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We insert a bitcast which obfuscates the getCalledFunction for the utility
function which looks up attributes from the called function. Loosing ABI
changing parameter attributes is a bad thing.

rdar://21516488

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242807 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Arnold Schwaighofer
2015-07-21 17:07:07 +00:00
parent 65671bf628
commit a5aae48d17
2 changed files with 59 additions and 0 deletions
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19
lib/Transforms/IPO/MergeFunctions.cpp
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@@ -1282,6 +1282,25 @@ void MergeFunctions::replaceDirectCallers(Function *Old, Function *New) {
++UI; ++UI;
CallSite CS(U->getUser()); CallSite CS(U->getUser());
if (CS && CS.isCallee(U)) { if (CS && CS.isCallee(U)) {
// Transfer the called function's attributes to the call site. Due to the
// bitcast we will 'loose' ABI changing attributes because the 'called
// function' is no longer a Function* but the bitcast. Code that looks up
// the attributes from the called function will fail.
auto &Context = New->getContext();
auto NewFuncAttrs = New->getAttributes();
auto CallSiteAttrs = CS.getAttributes();
CallSiteAttrs = CallSiteAttrs.addAttributes(
Context, AttributeSet::ReturnIndex, NewFuncAttrs.getRetAttributes());
for (unsigned argIdx = 0; argIdx < CS.arg_size(); argIdx++) {
AttributeSet Attrs = NewFuncAttrs.getParamAttributes(argIdx);
if (Attrs.getNumSlots())
CallSiteAttrs = CallSiteAttrs.addAttributes(Context, argIdx, Attrs);
}
CS.setAttributes(CallSiteAttrs);
remove(CS.getInstruction()->getParent()->getParent()); remove(CS.getInstruction()->getParent()->getParent());
U->set(BitcastNew); U->set(BitcastNew);
} }

40
test/Transforms/MergeFunc/apply_function_attributes.ll Normal file
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@@ -0,0 +1,40 @@
; RUN: opt -S -mergefunc < %s | FileCheck %s
%Opaque_type = type opaque
%S2i = type <{ i64, i64 }>
%D2i = type <{ i64, i64 }>
%Di = type <{ i32 }>
%Si = type <{ i32 }>
define void @B(%Opaque_type* sret %a, %S2i* %b, i32* %xp, i32* %yp) {
%x = load i32, i32* %xp
%y = load i32, i32* %yp
%sum = add i32 %x, %y
%sum2 = add i32 %sum, %y
%sum3 = add i32 %sum2, %y
ret void
}
define void @C(%Opaque_type* sret %a, %S2i* %b, i32* %xp, i32* %yp) {
%x = load i32, i32* %xp
%y = load i32, i32* %yp
%sum = add i32 %x, %y
%sum2 = add i32 %sum, %y
%sum3 = add i32 %sum2, %y
ret void
}
define void @A(%Opaque_type* sret %a, %D2i* %b, i32* %xp, i32* %yp) {
%x = load i32, i32* %xp
%y = load i32, i32* %yp
%sum = add i32 %x, %y
%sum2 = add i32 %sum, %y
%sum3 = add i32 %sum2, %y
ret void
}
; Make sure we transfer the parameter attributes to the call site.
; CHECK-LABEL: define void @C(%Opaque_type* sret
; CHECK: tail call void bitcast (void (%Opaque_type*, %D2i*, i32*, i32*)* @A to void (%Opaque_type*, %S2i*, i32*, i32*)*)(%Opaque_type* sret %0, %S2i* %1, i32* %2, i32* %3)
; CHECK: ret void