From b074e3264176b097bf9e9b9b4359af3394cad58e Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Fri, 28 Jan 2011 03:28:10 +0000
Subject: Fold select + select where both selects are on the same condition.

llvm-svn: 124469
---
 llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

(limited to 'llvm/lib/Transforms')

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index ff41ab834b1..97abc769ae5 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -792,6 +792,19 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
       if (Instruction *NV = FoldOpIntoPhi(SI))
         return NV;
 
+  if (SelectInst *TrueSI = dyn_cast<SelectInst>(TrueVal)) {
+    if (TrueSI->getCondition() == CondVal) {
+      SI.setOperand(1, TrueSI->getTrueValue());
+      return &SI;
+    }
+  }
+  if (SelectInst *FalseSI = dyn_cast<SelectInst>(FalseVal)) {
+    if (FalseSI->getCondition() == CondVal) {
+      SI.setOperand(2, FalseSI->getFalseValue());
+      return &SI;
+    }
+  }
+
   if (BinaryOperator::isNot(CondVal)) {
     SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
     SI.setOperand(1, FalseVal);
-- 
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