From 8e43417d2f59387b31b5aa0b291d53d8681c0752 Mon Sep 17 00:00:00 2001
From: Ahmed Bougacha <ahmed.bougacha@gmail.com>
Date: Sat, 26 Sep 2015 00:14:02 +0000
Subject: [PATCH] [ARM] Don't generate clrex for pre-v7 targets.

Since r248294, we emit clrex, but it doesn't exist on v6.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@248640 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMISelLowering.cpp |  2 ++
 test/CodeGen/ARM/atomic-cmpxchg.ll | 33 +++++++++++++++++++++++++++++-
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 213bd2ecc47..8a2deb6ebbf 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -11739,6 +11739,8 @@ Value *ARMTargetLowering::emitLoadLinked(IRBuilder<> &Builder, Value *Addr,
 
 void ARMTargetLowering::emitAtomicCmpXchgNoStoreLLBalance(
     IRBuilder<> &Builder) const {
+  if (!Subtarget->hasV7Ops())
+    return;
   Module *M = Builder.GetInsertBlock()->getParent()->getParent();
   Builder.CreateCall(llvm::Intrinsic::getDeclaration(M, Intrinsic::arm_clrex));
 }
diff --git a/test/CodeGen/ARM/atomic-cmpxchg.ll b/test/CodeGen/ARM/atomic-cmpxchg.ll
index 10db26c53e4..32cdf4174dd 100644
--- a/test/CodeGen/ARM/atomic-cmpxchg.ll
+++ b/test/CodeGen/ARM/atomic-cmpxchg.ll
@@ -1,6 +1,9 @@
 ; RUN: llc < %s -mtriple=arm-linux-gnueabi -asm-verbose=false -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-ARM
 ; RUN: llc < %s -mtriple=thumb-linux-gnueabi -asm-verbose=false -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-THUMB
 
+; RUN: llc < %s -mtriple=armv6-linux-gnueabi -asm-verbose=false -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-ARMV6
+; RUN: llc < %s -mtriple=thumbv6-linux-gnueabi -asm-verbose=false -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-THUMBV6
+
 ; RUN: llc < %s -mtriple=armv7-linux-gnueabi -asm-verbose=false -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-ARMV7
 ; RUN: llc < %s -mtriple=thumbv7-linux-gnueabi -asm-verbose=false -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-THUMBV7
 
@@ -26,10 +29,38 @@ entry:
 ; CHECK-THUMB: movs r0, #1
 ; CHECK-THUMB: movs [[R2:r[0-9]+]], #0
 ; CHECK-THUMB: cmp [[R1]], {{r[0-9]+}}
-; CHECK-THU<B: beq
+; CHECK-THUMB: beq
 ; CHECK-THUMB: push  {[[R2]]}
 ; CHECK-THUMB: pop {r0}
 
+; CHECK-ARMV6-LABEL: test_cmpxchg_res_i8:
+; CHECK-ARMV6-NEXT:  .fnstart
+; CHECK-ARMV6-NEXT: uxtb [[DESIRED:r[0-9]+]], r1
+; CHECK-ARMV6-NEXT: [[TRY:.LBB[0-9_]+]]:
+; CHECK-ARMV6-NEXT: ldrexb [[LD:r[0-9]+]], [r0]
+; CHECK-ARMV6-NEXT: mov [[RES:r[0-9]+]], #0
+; CHECK-ARMV6-NEXT: cmp [[LD]], [[DESIRED]]
+; CHECK-ARMV6-NEXT: bne [[END:.LBB[0-9_]+]]
+; CHECK-ARMV6-NEXT: strexb [[SUCCESS:r[0-9]+]], r2, [r0]
+; CHECK-ARMV6-NEXT: mov [[RES]], #1
+; CHECK-ARMV6-NEXT: cmp [[SUCCESS]], #0
+; CHECK-ARMV6-NEXT: bne [[TRY]]
+; CHECK-ARMV6-NEXT: [[END]]:
+; CHECK-ARMV6-NEXT: mov r0, [[RES]]
+; CHECK-ARMV6-NEXT: bx lr
+
+; CHECK-THUMBV6-LABEL: test_cmpxchg_res_i8:
+; CHECK-THUMBV6:       mov [[EXPECTED:r[0-9]+]], r1
+; CHECK-THUMBV6-NEXT:  bl __sync_val_compare_and_swap_1
+; CHECK-THUMBV6-NEXT:  mov [[RES:r[0-9]+]], r0
+; CHECK-THUMBV6-NEXT:  movs r0, #1
+; CHECK-THUMBV6-NEXT:  movs [[ZERO:r[0-9]+]], #0
+; CHECK-THUMBV6-NEXT:  cmp [[RES]], [[EXPECTED]]
+; CHECK-THUMBV6-NEXT:  beq [[END:.LBB[0-9_]+]]
+; CHECK-THUMBV6-NEXT:  mov r0, [[ZERO]]
+; CHECK-THUMBV6-NEXT: [[END]]:
+; CHECK-THUMBV6-NEXT:  pop {{.*}}pc}
+
 ; CHECK-ARMV7-LABEL: test_cmpxchg_res_i8:
 ; CHECK-ARMV7-NEXT: .fnstart
 ; CHECK-ARMV7-NEXT: uxtb [[DESIRED:r[0-9]+]], r1
-- 
2.34.1