From a5aae48d178b34160b8cdb9bb36c12c6b56d7b48 Mon Sep 17 00:00:00 2001
From: Arnold Schwaighofer <aschwaighofer@apple.com>
Date: Tue, 21 Jul 2015 17:07:07 +0000
Subject: [PATCH] MergeFunc: Transfer the callee's attributes when replacing a
direct caller
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
---
lib/Transforms/IPO/MergeFunctions.cpp | 19 +++++++++
.../MergeFunc/apply_function_attributes.ll | 40 +++++++++++++++++++
2 files changed, 59 insertions(+)
create mode 100644 test/Transforms/MergeFunc/apply_function_attributes.ll
diff --git a/lib/Transforms/IPO/MergeFunctions.cpp b/lib/Transforms/IPO/MergeFunctions.cpp
index 109cac7fece..7ece66302f9 100644
--- a/lib/Transforms/IPO/MergeFunctions.cpp
+++ b/lib/Transforms/IPO/MergeFunctions.cpp
@@ -1282,6 +1282,25 @@ void MergeFunctions::replaceDirectCallers(Function *Old, Function *New) {
++UI;
CallSite CS(U->getUser());
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());
U->set(BitcastNew);
}
diff --git a/test/Transforms/MergeFunc/apply_function_attributes.ll b/test/Transforms/MergeFunc/apply_function_attributes.ll
new file mode 100644
index 00000000000..fa7f052f7ff
--- /dev/null
+++ b/test/Transforms/MergeFunc/apply_function_attributes.ll
@@ -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
+
--
2.34.1