From d1ee7e0ba3b4f942e3bf3b2e9d6a02b186da4ec8 Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Fri, 26 Mar 2010 16:26:03 +0000
Subject: [PATCH] Do not sibcall if stack needs to be dynamically aligned.

llvm-svn: 99620
---
 lib/Target/X86/X86ISelLowering.cpp |  6 ++++++
 test/CodeGen/X86/sibcall.ll        | 11 +++++++++++
 2 files changed, 17 insertions(+)

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index d08dfc4eab5..707b9fe2c59 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -2290,6 +2290,7 @@ X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
     return false;
 
   // If -tailcallopt is specified, make fastcc functions tail-callable.
+  const MachineFunction &MF = DAG.getMachineFunction();
   const Function *CallerF = DAG.getMachineFunction().getFunction();
   if (GuaranteedTailCallOpt) {
     if (IsTailCallConvention(CalleeCC) &&
@@ -2301,6 +2302,11 @@ X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
   // Look for obvious safe cases to perform tail call optimization that does not
   // requite ABI changes. This is what gcc calls sibcall.
 
+  // Can't do sibcall if stack needs to be dynamically re-aligned. PEI needs to
+  // emit a special epilogue.
+  if (RegInfo->needsStackRealignment(MF))
+    return false;
+
   // Do not sibcall optimize vararg calls unless the call site is not passing any
   // arguments.
   if (isVarArg && !Outs.empty())
diff --git a/test/CodeGen/X86/sibcall.ll b/test/CodeGen/X86/sibcall.ll
index 541e7506b8b..8e52a7cbfe7 100644
--- a/test/CodeGen/X86/sibcall.ll
+++ b/test/CodeGen/X86/sibcall.ll
@@ -302,3 +302,14 @@ entry:
 }
 
 declare double @bar6(...)
+
+define void @t19() alignstack(32) nounwind {
+entry:
+; CHECK: t19:
+; CHECK: andl $-32
+; CHECK: call {{_?}}foo
+  tail call void @foo() nounwind
+  ret void
+}
+
+declare void @foo()