From 7cfa656ad84306ded61f0a3c7a8862505f48c239 Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Tue, 25 Jan 2011 01:28:33 +0000
Subject: [PATCH] Don't merge restore with tail call instruction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124167 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMFrameLowering.cpp |  7 ++++++-
 test/CodeGen/ARM/call-tc.ll         | 22 ++++++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/lib/Target/ARM/ARMFrameLowering.cpp b/lib/Target/ARM/ARMFrameLowering.cpp
index c2739f6d6d5..70838f5d11c 100644
--- a/lib/Target/ARM/ARMFrameLowering.cpp
+++ b/lib/Target/ARM/ARMFrameLowering.cpp
@@ -586,6 +586,11 @@ void ARMFrameLowering::emitPopInst(MachineBasicBlock &MBB,
   const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
   ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
   DebugLoc DL = MI->getDebugLoc();
+  unsigned RetOpcode = MI->getOpcode();
+  bool isTailCall = (RetOpcode == ARM::TCRETURNdi ||
+                     RetOpcode == ARM::TCRETURNdiND ||
+                     RetOpcode == ARM::TCRETURNri ||
+                     RetOpcode == ARM::TCRETURNriND);
 
   SmallVector<unsigned, 4> Regs;
   unsigned i = CSI.size();
@@ -596,7 +601,7 @@ void ARMFrameLowering::emitPopInst(MachineBasicBlock &MBB,
       unsigned Reg = CSI[i-1].getReg();
       if (!(Func)(Reg, STI.isTargetDarwin())) continue;
 
-      if (Reg == ARM::LR && !isVarArg && STI.hasV5TOps()) {
+      if (Reg == ARM::LR && !isTailCall && !isVarArg && STI.hasV5TOps()) {
         Reg = ARM::PC;
         LdmOpc = AFI->isThumbFunction() ? ARM::t2LDMIA_RET : ARM::LDMIA_RET;
         // Fold the return instruction into the LDM.
diff --git a/test/CodeGen/ARM/call-tc.ll b/test/CodeGen/ARM/call-tc.ll
index 213db5e1d01..a77aba037be 100644
--- a/test/CodeGen/ARM/call-tc.ll
+++ b/test/CodeGen/ARM/call-tc.ll
@@ -1,5 +1,6 @@
 ; RUN: llc < %s -mtriple=armv6-apple-darwin -mattr=+vfp2 -arm-tail-calls | FileCheck %s -check-prefix=CHECKV6
 ; RUN: llc < %s -mtriple=armv6-linux-gnueabi -relocation-model=pic -mattr=+vfp2 -arm-tail-calls | FileCheck %s -check-prefix=CHECKELF
+; RUN: llc < %s -mtriple=thumbv7-apple-darwin -arm-tail-calls | FileCheck %s -check-prefix=CHECKT2
 
 @t = weak global i32 ()* null           ; <i32 ()**> [#uses=1]
 
@@ -63,3 +64,24 @@ entry:
   %0 = sdiv i32 %a, %b
   ret i32 %0
 }
+
+; Make sure the tail call instruction isn't deleted
+; rdar://8309338
+declare void @foo() nounwind
+
+define void @t7() nounwind {
+entry:
+; CHECKT2: t7:
+; CHECKT2: blxeq _foo
+; CHECKT2-NEXT: pop.w
+; CHECKT2-NEXT: b.w _foo
+  br i1 undef, label %bb, label %bb1.lr.ph
+
+bb1.lr.ph:
+  tail call void @foo() nounwind
+  unreachable
+
+bb:
+  tail call void @foo() nounwind
+  ret void
+}