Don't let a noalias difference disrupt the tailcall optimization.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@88672 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
index b3d8d1d..f2c623c 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
@@ -4349,7 +4349,7 @@
/// TargetLowering::IsEligibleForTailCallOptimization.
///
static bool
-isInTailCallPosition(const Instruction *I, Attributes RetAttr,
+isInTailCallPosition(const Instruction *I, Attributes CalleeRetAttr,
const TargetLowering &TLI) {
const BasicBlock *ExitBB = I->getParent();
const TerminatorInst *Term = ExitBB->getTerminator();
@@ -4377,8 +4377,9 @@
if (!Ret || Ret->getNumOperands() == 0) return true;
// Conservatively require the attributes of the call to match those of
- // the return.
- if (F->getAttributes().getRetAttributes() != RetAttr)
+ // the return. Ignore noalias because it doesn't affect the call sequence.
+ unsigned CallerRetAttr = F->getAttributes().getRetAttributes();
+ if ((CalleeRetAttr ^ CallerRetAttr) & ~Attribute::NoAlias)
return false;
// Otherwise, make sure the unmodified return value of I is the return value.
diff --git a/test/CodeGen/X86/tailcall1.ll b/test/CodeGen/X86/tailcall1.ll
index a4f87c0..215d009 100644
--- a/test/CodeGen/X86/tailcall1.ll
+++ b/test/CodeGen/X86/tailcall1.ll
@@ -1,4 +1,4 @@
-; RUN: llc < %s -march=x86 -tailcallopt | grep TAILCALL
+; RUN: llc < %s -march=x86 -tailcallopt | grep TAILCALL | count 3
define fastcc i32 @tailcallee(i32 %a1, i32 %a2, i32 %a3, i32 %a4) {
entry:
ret i32 %a3
@@ -9,3 +9,17 @@
%tmp11 = tail call fastcc i32 @tailcallee( i32 %in1, i32 %in2, i32 %in1, i32 %in2 ) ; <i32> [#uses=1]
ret i32 %tmp11
}
+
+declare fastcc i8* @alias_callee()
+
+define fastcc noalias i8* @noalias_caller() nounwind {
+ %p = tail call fastcc i8* @alias_callee()
+ ret i8* %p
+}
+
+declare fastcc noalias i8* @noalias_callee()
+
+define fastcc i8* @alias_caller() nounwind {
+ %p = tail call fastcc noalias i8* @noalias_callee()
+ ret i8* %p
+}