From 74bd0360596cb306da06bfd5d94b5dc4665ca301 Mon Sep 17 00:00:00 2001
From: Reid Spencer <rspencer@reidspencer.com>
Date: Thu, 11 Jan 2007 00:25:45 +0000
Subject: [PATCH] Implement better constant folding of unordered FCMP
 predicates.

llvm-svn: 33063
---
 llvm/lib/VMCore/ConstantFolding.cpp | 34 +++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/llvm/lib/VMCore/ConstantFolding.cpp b/llvm/lib/VMCore/ConstantFolding.cpp
index 6215bdd438b6..fffba1e6f941 100644
--- a/llvm/lib/VMCore/ConstantFolding.cpp
+++ b/llvm/lib/VMCore/ConstantFolding.cpp
@@ -1110,18 +1110,38 @@ Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
     case FCmpInst::FCMP_FALSE: return ConstantBool::getFalse();
     case FCmpInst::FCMP_TRUE:  return ConstantBool::getTrue();
     case FCmpInst::FCMP_UNO:
-    case FCmpInst::FCMP_ORD:   break; // Can't fold these
+      return ConstantBool::get(C1Val != C1Val || C2Val != C2Val);
+    case FCmpInst::FCMP_ORD:
+      return ConstantBool::get(C1Val == C1Val && C2Val == C2Val);
     case FCmpInst::FCMP_UEQ:
+      if (C1Val != C1Val || C2Val != C2Val)
+        return ConstantBool::getTrue();
+      /* FALL THROUGH */
     case FCmpInst::FCMP_OEQ:   return ConstantBool::get(C1Val == C2Val);
-    case FCmpInst::FCMP_ONE:
-    case FCmpInst::FCMP_UNE:   return ConstantBool::get(C1Val != C2Val);
-    case FCmpInst::FCMP_OLT: 
-    case FCmpInst::FCMP_ULT:   return ConstantBool::get(C1Val < C2Val);
+    case FCmpInst::FCMP_UNE:
+      if (C1Val != C1Val || C2Val != C2Val)
+        return ConstantBool::getTrue();
+      /* FALL THROUGH */
+    case FCmpInst::FCMP_ONE:   return ConstantBool::get(C1Val != C2Val);
+    case FCmpInst::FCMP_ULT: 
+      if (C1Val != C1Val || C2Val != C2Val)
+        return ConstantBool::getTrue();
+      /* FALL THROUGH */
+    case FCmpInst::FCMP_OLT:   return ConstantBool::get(C1Val < C2Val);
     case FCmpInst::FCMP_UGT:
+      if (C1Val != C1Val || C2Val != C2Val)
+        return ConstantBool::getTrue();
+      /* FALL THROUGH */
     case FCmpInst::FCMP_OGT:   return ConstantBool::get(C1Val > C2Val);
-    case FCmpInst::FCMP_OLE:
-    case FCmpInst::FCMP_ULE:   return ConstantBool::get(C1Val <= C2Val);
+    case FCmpInst::FCMP_ULE:
+      if (C1Val != C1Val || C2Val != C2Val)
+        return ConstantBool::getTrue();
+      /* FALL THROUGH */
+    case FCmpInst::FCMP_OLE:   return ConstantBool::get(C1Val <= C2Val);
     case FCmpInst::FCMP_UGE:
+      if (C1Val != C1Val || C2Val != C2Val)
+        return ConstantBool::getTrue();
+      /* FALL THROUGH */
     case FCmpInst::FCMP_OGE:   return ConstantBool::get(C1Val >= C2Val);
     }
   } else if (const ConstantPacked *CP1 = dyn_cast<ConstantPacked>(C1)) {