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Remove conflicting attributes before adding deduced readonly/readnone 

Summary:
In case of functions that have a pointer argument and only pass it to
each other, the function attributes pass deduces that the pointer should
get the readnone attribute, but fails to remove a readonly attribute
that may already have been present.

Reviewers: nlewycky

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9995

llvm-svn: 238152
This commit is contained in:
Bjorn Steinbrink 2015-05-25 19:46:38 +00:00
parent f071bd0a18
commit 236446cd4c
2 changed files with 18 additions and 1 deletions
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6
llvm/lib/Transforms/IPO/FunctionAttrs.cpp
View File

@ -703,10 +703,14 @@ bool FunctionAttrs::AddArgumentAttrs(const CallGraphSCC &SCC) {
} }
if (ReadAttr != Attribute::None) { if (ReadAttr != Attribute::None) {
AttrBuilder B; AttrBuilder B, R;
B.addAttribute(ReadAttr); B.addAttribute(ReadAttr);
R.addAttribute(Attribute::ReadOnly)
.addAttribute(Attribute::ReadNone);
for (unsigned i = 0, e = ArgumentSCC.size(); i != e; ++i) { for (unsigned i = 0, e = ArgumentSCC.size(); i != e; ++i) {
Argument *A = ArgumentSCC[i]->Definition; Argument *A = ArgumentSCC[i]->Definition;
// Clear out existing readonly/readnone attributes
A->removeAttr(AttributeSet::get(A->getContext(), A->getArgNo() + 1, R));
A->addAttr(AttributeSet::get(A->getContext(), A->getArgNo() + 1, B)); A->addAttr(AttributeSet::get(A->getContext(), A->getArgNo() + 1, B));
ReadAttr == Attribute::ReadOnly ? ++NumReadOnlyArg : ++NumReadNoneArg; ReadAttr == Attribute::ReadOnly ? ++NumReadOnlyArg : ++NumReadNoneArg;
Changed = true; Changed = true;

13
llvm/test/Transforms/FunctionAttrs/readnone.ll Normal file
View File

@ -0,0 +1,13 @@
; RUN: opt < %s -functionattrs -S | FileCheck %s
; CHECK: define void @bar(i8* nocapture readnone)
define void @bar(i8* readonly) {
call void @foo(i8* %0)
ret void
}
; CHECK: define void @foo(i8* nocapture readnone)
define void @foo(i8* readonly) {
call void @bar(i8* %0)
ret void
}