From d155d7e428e0e14b520dddbf00b6745d7eb2d7b8 Mon Sep 17 00:00:00 2001
From: Dale Johannesen <dalej@apple.com>
Date: Mon, 25 Oct 2010 22:17:05 +0000
Subject: [PATCH] An stdcall function calling a non-stdcall function cannot use
 tailcall.  PR 8461.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117322 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/X86/X86ISelLowering.cpp     |  5 +++++
 test/CodeGen/X86/stdcall-notailcall.ll | 13 +++++++++++++
 2 files changed, 18 insertions(+)
 create mode 100644 test/CodeGen/X86/stdcall-notailcall.ll

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index ca812c84bd6..f698ceceac5 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -2532,6 +2532,11 @@ X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
     }
   }
 
+  // An stdcall caller is expected to clean up its arguments; the callee
+  // isn't going to do that.   PR 8461.
+  if (!CCMatch && CallerCC==CallingConv::X86_StdCall)
+    return false;
+
   return true;
 }
 
diff --git a/test/CodeGen/X86/stdcall-notailcall.ll b/test/CodeGen/X86/stdcall-notailcall.ll
new file mode 100644
index 00000000000..8e33c30bf29
--- /dev/null
+++ b/test/CodeGen/X86/stdcall-notailcall.ll
@@ -0,0 +1,13 @@
+; RUN: llc -mtriple=i386-apple-darwin11 -O2 < %s | FileCheck %s
+
+%struct.I = type { i32 (...)** }
+define x86_stdcallcc void @bar(%struct.I* nocapture %this) ssp align 2 {
+; CHECK: bar:
+; CHECK-NOT: jmp
+; CHECK: ret $4
+entry:
+  tail call void @foo()
+  ret void
+}
+
+declare void @foo()