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
diff --git a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
index 0166935..92e384a 100644
--- a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -703,10 +703,14 @@
}
if (ReadAttr != Attribute::None) {
- AttrBuilder B;
+ AttrBuilder B, R;
B.addAttribute(ReadAttr);
+ R.addAttribute(Attribute::ReadOnly)
+ .addAttribute(Attribute::ReadNone);
for (unsigned i = 0, e = ArgumentSCC.size(); i != e; ++i) {
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));
ReadAttr == Attribute::ReadOnly ? ++NumReadOnlyArg : ++NumReadNoneArg;
Changed = true;
diff --git a/llvm/test/Transforms/FunctionAttrs/readnone.ll b/llvm/test/Transforms/FunctionAttrs/readnone.ll
new file mode 100644
index 0000000..eddcdd2
--- /dev/null
+++ b/llvm/test/Transforms/FunctionAttrs/readnone.ll
@@ -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
+}