From 892143ff70b5e7d0cb06e7c4596c232347806b17 Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Wed, 28 Mar 2012 23:07:03 +0000
Subject: [PATCH] Don't kill the base register when expanding strd.

When an strd instruction doesn't get the registers it wants, it can be
expanded into two str instructions. Make sure the first str doesn't kill
the base register in the case where the base and data registers are
identical:

  t2STRi12 %R0<kill>, %R0, 4, pred:14, pred:%noreg
  t2STRi12 %R2<kill>, %R0, 8, pred:14, pred:%noreg

<rdar://problem/11101911>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153611 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMLoadStoreOptimizer.cpp |  4 ++++
 test/CodeGen/Thumb2/crash.ll             | 15 +++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
index f75ac90b22e..5770f7739ae 100644
--- a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
+++ b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
@@ -1184,6 +1184,10 @@ bool ARMLoadStoreOpt::FixInvalidRegPairOp(MachineBasicBlock &MBB,
           EvenDeadKill = false;
           OddDeadKill = true;
         }
+        // Never kill the base register in the first instruction.
+        // <rdar://problem/11101911>
+        if (EvenReg == BaseReg)
+          EvenDeadKill = false;
         InsertLDR_STR(MBB, MBBI, OffImm, isLd, dl, NewOpc,
                       EvenReg, EvenDeadKill, EvenUndef,
                       BaseReg, false, BaseUndef, false, OffUndef,
diff --git a/test/CodeGen/Thumb2/crash.ll b/test/CodeGen/Thumb2/crash.ll
index 52893af9370..cb4d08058f4 100644
--- a/test/CodeGen/Thumb2/crash.ll
+++ b/test/CodeGen/Thumb2/crash.ll
@@ -61,3 +61,18 @@ entry:
 declare <4 x float> @llvm.arm.neon.vld1.v4f32(i8*, i32) nounwind readonly
 
 declare void @llvm.arm.neon.vst1.v4f32(i8*, <4 x float>, i32) nounwind
+
+; <rdar://problem/11101911>
+; When an strd is expanded into two str instructions, make sure the first str
+; doesn't kill the base register. This can happen if the base register is the
+; same as the data register.
+%class = type { i8*, %class*, i32 }
+define void @f11101911(%class* %this, i32 %num) ssp align 2 {
+entry:
+  %p1 = getelementptr inbounds %class* %this, i32 0, i32 1
+  %p2 = getelementptr inbounds %class* %this, i32 0, i32 2
+  tail call void asm sideeffect "", "~{r1},~{r3},~{r5},~{r11},~{r13}"() nounwind
+  store %class* %this, %class** %p1, align 4
+  store i32 %num, i32* %p2, align 4
+  ret void
+}