From 1cd05bb605e3c3eee9197d3f10b628c60d0cc07a Mon Sep 17 00:00:00 2001
From: Duncan Sands <baldrick@free.fr>
Date: Wed, 22 Dec 2010 17:15:25 +0000
Subject: [PATCH] When determining whether the new instruction was already
 present in the original instruction, half the cases were missed (making it
 not wrong but suboptimal).  Also correct a typo (A <-> B) in the second
 chunk.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122414 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/InstructionSimplify.cpp               | 14 ++++++++------
 .../InstSimplify/2010-12-20-Distribute.ll          | 11 +++++++++++
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index a720987e52b..fb51fa5315b 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -159,10 +159,11 @@ static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
     // Does "B op DD" simplify?
     if (Value *V = SimplifyBinOp(Opcode, B, DD, TD, DT, MaxRecurse)) {
       // It does!  Return "A op' V" if it simplifies or is already available.
-      // If V equals B then "A op' V" is just the LHS.
-      if (V == B) {
+      // If V equals B then "A op' V" is just the LHS.  If V equals DD then
+      // "A op' V" is just the RHS.
+      if (V == B || V == DD) {
         ++NumFactor;
-        return LHS;
+        return V == B ? LHS : RHS;
       }
       // Otherwise return "A op' V" if it simplifies.
       if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, TD, DT, MaxRecurse)) {
@@ -181,10 +182,11 @@ static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
     // Does "A op CC" simplify?
     if (Value *V = SimplifyBinOp(Opcode, A, CC, TD, DT, MaxRecurse)) {
       // It does!  Return "V op' B" if it simplifies or is already available.
-      // If V equals A then "V op' B" is just the LHS.
-      if (V == B) {
+      // If V equals A then "V op' B" is just the LHS.  If V equals CC then
+      // "V op' B" is just the RHS.
+      if (V == A || V == CC) {
         ++NumFactor;
-        return LHS;
+        return V == A ? LHS : RHS;
       }
       // Otherwise return "V op' B" if it simplifies.
       if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, TD, DT, MaxRecurse)) {
diff --git a/test/Transforms/InstSimplify/2010-12-20-Distribute.ll b/test/Transforms/InstSimplify/2010-12-20-Distribute.ll
index 4aac8dd5884..60cef484469 100644
--- a/test/Transforms/InstSimplify/2010-12-20-Distribute.ll
+++ b/test/Transforms/InstSimplify/2010-12-20-Distribute.ll
@@ -20,6 +20,17 @@ define i32 @factorize2(i32 %x) {
 ; CHECK: ret i32 %x
 }
 
+define i32 @factorize3(i32 %x, i32 %a, i32 %b) {
+; CHECK: @factorize3
+; (X | (A|B)) & (X | B) -> X | ((A|B) & B) -> X | B
+  %aORb = or i32 %a, %b
+  %l = or i32 %x, %aORb
+  %r = or i32 %x, %b
+  %z = and i32 %l, %r
+  ret i32 %z
+; CHECK: ret i32 %r
+}
+
 define i32 @expand(i32 %x) {
 ; CHECK: @expand
 ; ((X & 1) | 2) & 1 -> ((X & 1) & 1) | (2 & 1) -> (X & 1) | 0 -> X & 1