From 6b7bb42c365e9b11eda2df67aa5da6aad7632356 Mon Sep 17 00:00:00 2001
From: Eli Friedman <eli.friedman@gmail.com>
Date: Fri, 19 Jun 2009 01:43:08 +0000
Subject: [PATCH] Mark a few Thumb instructions commutable; just happened to
 spot this while experimenting.  I'm reasonably sure this is correct, but
 please tell me if these instructions have some strange property which makes
 this change unsafe.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73746 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMInstrThumb.td                | 5 +++++
 test/CodeGen/ARM/2009-06-18-ThumbCommuteMul.ll | 8 ++++++++
 2 files changed, 13 insertions(+)
 create mode 100644 test/CodeGen/ARM/2009-06-18-ThumbCommuteMul.ll

diff --git a/lib/Target/ARM/ARMInstrThumb.td b/lib/Target/ARM/ARMInstrThumb.td
index 54232f6dfe6..9297f08d800 100644
--- a/lib/Target/ARM/ARMInstrThumb.td
+++ b/lib/Target/ARM/ARMInstrThumb.td
@@ -277,6 +277,7 @@ def tPUSH : TI<(outs), (ins reglist:$src1, variable_ops),
 //
 
 // Add with carry
+let isCommutable = 1 in
 def tADC : TIt<(outs tGPR:$dst), (ins tGPR:$lhs, tGPR:$rhs),
                "adc $dst, $rhs",
                [(set tGPR:$dst, (adde tGPR:$lhs, tGPR:$rhs))]>;
@@ -311,6 +312,7 @@ def tADDrSPi : TI<(outs tGPR:$dst), (ins GPR:$sp, i32imm:$rhs),
 def tADDspi : TIt<(outs GPR:$dst), (ins GPR:$lhs, i32imm:$rhs),
                   "add $dst, $rhs * 4", []>;
 
+let isCommutable = 1 in
 def tAND : TIt<(outs tGPR:$dst), (ins tGPR:$lhs, tGPR:$rhs),
                 "and $dst, $rhs",
                 [(set tGPR:$dst, (and tGPR:$lhs, tGPR:$rhs))]>;
@@ -358,6 +360,7 @@ def tCMPNZr : TI<(outs), (ins tGPR:$lhs, tGPR:$rhs),
 
 // TODO: A7-37: CMP(3) - cmp hi regs
 
+let isCommutable = 1 in
 def tEOR : TIt<(outs tGPR:$dst), (ins tGPR:$lhs, tGPR:$rhs),
                "eor $dst, $rhs",
                [(set tGPR:$dst, (xor tGPR:$lhs, tGPR:$rhs))]>;
@@ -399,6 +402,7 @@ def tMOVhir2hir : TI<(outs GPR:$dst), (ins GPR:$src),
                       "cpy $dst, $src\t@ hir2hir", []>;
 } // neverHasSideEffects
 
+let isCommutable = 1 in
 def tMUL : TIt<(outs tGPR:$dst), (ins tGPR:$lhs, tGPR:$rhs),
                "mul $dst, $rhs",
                [(set tGPR:$dst, (mul tGPR:$lhs, tGPR:$rhs))]>;
@@ -411,6 +415,7 @@ def tNEG : TI<(outs tGPR:$dst), (ins tGPR:$src),
               "neg $dst, $src",
               [(set tGPR:$dst, (ineg tGPR:$src))]>;
 
+let isCommutable = 1 in
 def tORR : TIt<(outs tGPR:$dst), (ins tGPR:$lhs, tGPR:$rhs),
                "orr $dst, $rhs",
                [(set tGPR:$dst, (or tGPR:$lhs, tGPR:$rhs))]>;
diff --git a/test/CodeGen/ARM/2009-06-18-ThumbCommuteMul.ll b/test/CodeGen/ARM/2009-06-18-ThumbCommuteMul.ll
new file mode 100644
index 00000000000..9b2aba94ec8
--- /dev/null
+++ b/test/CodeGen/ARM/2009-06-18-ThumbCommuteMul.ll
@@ -0,0 +1,8 @@
+; RUN: llvm-as < %s | llc -march=thumb | grep r0 | count 1
+
+define i32 @a(i32 %x, i32 %y) nounwind readnone {
+entry:
+	%mul = mul i32 %y, %x		; <i32> [#uses=1]
+	ret i32 %mul
+}
+