From 10469f8e48e007989b0469e677d4000a1311ecd2 Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Thu, 1 Oct 2009 20:54:53 +0000
Subject: [PATCH] ARM::tPOP and tPOP_RET each has an extra writeback operand
 now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83214 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMConstantIslandPass.cpp |  6 ++++--
 lib/Target/ARM/Thumb1InstrInfo.cpp       |  1 +
 lib/Target/ARM/Thumb1RegisterInfo.cpp    |  1 +
 test/CodeGen/Thumb/pop.ll                | 13 +++++++++++++
 4 files changed, 19 insertions(+), 2 deletions(-)
 create mode 100644 test/CodeGen/Thumb/pop.ll

diff --git a/lib/Target/ARM/ARMConstantIslandPass.cpp b/lib/Target/ARM/ARMConstantIslandPass.cpp
index c44ea2ea2ad..43a823daee0 100644
--- a/lib/Target/ARM/ARMConstantIslandPass.cpp
+++ b/lib/Target/ARM/ARMConstantIslandPass.cpp
@@ -1359,9 +1359,11 @@ bool ARMConstantIslands::UndoLRSpillRestore() {
   bool MadeChange = false;
   for (unsigned i = 0, e = PushPopMIs.size(); i != e; ++i) {
     MachineInstr *MI = PushPopMIs[i];
+    // First two operands are predicates, the third is a zero since there
+    // is no writeback.
     if (MI->getOpcode() == ARM::tPOP_RET &&
-        MI->getOperand(2).getReg() == ARM::PC &&
-        MI->getNumExplicitOperands() == 3) {
+        MI->getOperand(3).getReg() == ARM::PC &&
+        MI->getNumExplicitOperands() == 4) {
       BuildMI(MI->getParent(), MI->getDebugLoc(), TII->get(ARM::tBX_RET));
       MI->eraseFromParent();
       MadeChange = true;
diff --git a/lib/Target/ARM/Thumb1InstrInfo.cpp b/lib/Target/ARM/Thumb1InstrInfo.cpp
index dc4ce64fe75..e1f9338bc3f 100644
--- a/lib/Target/ARM/Thumb1InstrInfo.cpp
+++ b/lib/Target/ARM/Thumb1InstrInfo.cpp
@@ -178,6 +178,7 @@ restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
   DebugLoc DL = MI->getDebugLoc();
   MachineInstrBuilder MIB = BuildMI(MF, DL, get(ARM::tPOP));
   AddDefaultPred(MIB);
+  MIB.addReg(0); // No write back.
 
   bool NumRegs = 0;
   for (unsigned i = CSI.size(); i != 0; --i) {
diff --git a/lib/Target/ARM/Thumb1RegisterInfo.cpp b/lib/Target/ARM/Thumb1RegisterInfo.cpp
index ea5f0727a10..0cea27f74d3 100644
--- a/lib/Target/ARM/Thumb1RegisterInfo.cpp
+++ b/lib/Target/ARM/Thumb1RegisterInfo.cpp
@@ -863,6 +863,7 @@ void Thumb1RegisterInfo::emitEpilogue(MachineFunction &MF,
     // Epilogue for vararg functions: pop LR to R3 and branch off it.
     // FIXME: Verify this is still ok when R3 is no longer being reserved.
     AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tPOP)))
+      .addReg(0) // No write back.
       .addReg(ARM::R3, RegState::Define);
 
     emitSPUpdate(MBB, MBBI, TII, dl, *this, VARegSaveSize);
diff --git a/test/CodeGen/Thumb/pop.ll b/test/CodeGen/Thumb/pop.ll
new file mode 100644
index 00000000000..c5e86ad45bc
--- /dev/null
+++ b/test/CodeGen/Thumb/pop.ll
@@ -0,0 +1,13 @@
+; RUN: llc < %s -mtriple=thumb-apple-darwin | FileCheck %s
+; rdar://7268481
+
+define arm_apcscc void @t(i8* %a, ...) nounwind {
+; CHECK:      t:
+; CHECK:      pop {r3}
+; CHECK-NEXT: add sp, #3 * 4
+; CHECK-NEXT: bx r3
+entry:
+  %a.addr = alloca i8*
+  store i8* %a, i8** %a.addr
+  ret void
+}