From 789fef987f9c3dd14743731e3a6733f2f90c9778 Mon Sep 17 00:00:00 2001
From: Bob Wilson <bob.wilson@apple.com>
Date: Thu, 24 Jun 2010 16:50:20 +0000
Subject: [PATCH] PR7458: Try commuting Thumb2 instruction operands to put them
 into 2-address form so they can be narrowed to 16-bit instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106762 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/Thumb2SizeReduction.cpp | 14 +++++++++++---
 test/CodeGen/Thumb2/thumb2-eor.ll      |  9 ++++++++-
 test/CodeGen/Thumb2/thumb2-uxtb.ll     |  2 +-
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/lib/Target/ARM/Thumb2SizeReduction.cpp b/lib/Target/ARM/Thumb2SizeReduction.cpp
index 4ad21c49a8a..ba392f36d94 100644
--- a/lib/Target/ARM/Thumb2SizeReduction.cpp
+++ b/lib/Target/ARM/Thumb2SizeReduction.cpp
@@ -451,11 +451,18 @@ Thumb2SizeReduce::ReduceTo2Addr(MachineBasicBlock &MBB, MachineInstr *MI,
   if (ReduceLimit2Addr != -1 && ((int)Num2Addrs >= ReduceLimit2Addr))
     return false;
 
-  const TargetInstrDesc &TID = MI->getDesc();
   unsigned Reg0 = MI->getOperand(0).getReg();
   unsigned Reg1 = MI->getOperand(1).getReg();
-  if (Reg0 != Reg1)
-    return false;
+  if (Reg0 != Reg1) {
+    // Try to commute the operands to make it a 2-address instruction.
+    unsigned CommOpIdx1, CommOpIdx2;
+    if (!TII->findCommutedOpIndices(MI, CommOpIdx1, CommOpIdx2) ||
+        CommOpIdx1 != 1 || MI->getOperand(CommOpIdx2).getReg() != Reg0)
+      return false;
+    MachineInstr *CommutedMI = TII->commuteInstruction(MI);
+    if (!CommutedMI)
+      return false;
+  }
   if (Entry.LowRegs2 && !isARMLowRegister(Reg0))
     return false;
   if (Entry.Imm2Limit) {
@@ -484,6 +491,7 @@ Thumb2SizeReduce::ReduceTo2Addr(MachineBasicBlock &MBB, MachineInstr *MI,
 
   bool HasCC = false;
   bool CCDead = false;
+  const TargetInstrDesc &TID = MI->getDesc();
   if (TID.hasOptionalDef()) {
     unsigned NumOps = TID.getNumOperands();
     HasCC = (MI->getOperand(NumOps-1).getReg() == ARM::CPSR);
diff --git a/test/CodeGen/Thumb2/thumb2-eor.ll b/test/CodeGen/Thumb2/thumb2-eor.ll
index b7e276673c4..116a1a3519a 100644
--- a/test/CodeGen/Thumb2/thumb2-eor.ll
+++ b/test/CodeGen/Thumb2/thumb2-eor.ll
@@ -9,11 +9,18 @@ define i32 @f1(i32 %a, i32 %b) {
 
 define i32 @f2(i32 %a, i32 %b) {
 ; CHECK: f2:
-; CHECK: eor.w r0, r1, r0
+; CHECK: eors r0, r1
     %tmp = xor i32 %b, %a
     ret i32 %tmp
 }
 
+define i32 @f2b(i32 %a, i32 %b, i32 %c) {
+; CHECK: f2b:
+; CHECK: eor.w r0, r1, r2
+    %tmp = xor i32 %b, %c
+    ret i32 %tmp
+}
+
 define i32 @f3(i32 %a, i32 %b) {
 ; CHECK: f3:
 ; CHECK: eor.w r0, r0, r1, lsl #5
diff --git a/test/CodeGen/Thumb2/thumb2-uxtb.ll b/test/CodeGen/Thumb2/thumb2-uxtb.ll
index 541191400b1..724dbbddb12 100644
--- a/test/CodeGen/Thumb2/thumb2-uxtb.ll
+++ b/test/CodeGen/Thumb2/thumb2-uxtb.ll
@@ -87,7 +87,7 @@ define i32 @test10(i32 %p0) {
 ; CHECK: and.w r0, r1, r0, lsr #7
 ; CHECK: lsrs  r1, r0, #5
 ; CHECK: uxtb16  r1, r1
-; CHECK: orr.w r0, r1, r0
+; CHECK: orrs r0, r1
 
 	%tmp1 = lshr i32 %p0, 7		; <i32> [#uses=1]
 	%tmp2 = and i32 %tmp1, 16253176		; <i32> [#uses=2]