[InstSimplify] fold select (fcmp X, Y), X, Y

This is NFCI for InstCombine because it calls InstSimplify, 
so I left the tests for this transform there. As noted in
the code comment, we can allow this fold more often by using
FMF and/or value tracking.

llvm-svn: 346169

1 files changed, 0 insertions, 50 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 724662f0128..88a72bb8eb5 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -1660,31 +1660,6 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
   // See if we are selecting two values based on a comparison of the two values.
   if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
     if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
-      // Transform (X == Y) ? X : Y  -> Y
-      if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
-        // This is not safe in general for floating point:
-        // consider X== -0, Y== +0.
-        // It becomes safe if either operand is a nonzero constant.
-        ConstantFP *CFPt, *CFPf;
-        if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
-              !CFPt->getValueAPF().isZero()) ||
-            ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
-             !CFPf->getValueAPF().isZero()))
-        return replaceInstUsesWith(SI, FalseVal);
-      }
-      // Transform (X une Y) ? X : Y  -> X
-      if (FCI->getPredicate() == FCmpInst::FCMP_UNE) {
-        // This is not safe in general for floating point:
-        // consider X== -0, Y== +0.
-        // It becomes safe if either operand is a nonzero constant.
-        ConstantFP *CFPt, *CFPf;
-        if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
-              !CFPt->getValueAPF().isZero()) ||
-            ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
-             !CFPf->getValueAPF().isZero()))
-        return replaceInstUsesWith(SI, TrueVal);
-      }
-
       // Canonicalize to use ordered comparisons by swapping the select
       // operands.
       //
@@ -1703,31 +1678,6 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
 
       // NOTE: if we wanted to, this is where to detect MIN/MAX
     } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
-      // Transform (X == Y) ? Y : X  -> X
-      if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
-        // This is not safe in general for floating point:
-        // consider X== -0, Y== +0.
-        // It becomes safe if either operand is a nonzero constant.
-        ConstantFP *CFPt, *CFPf;
-        if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
-              !CFPt->getValueAPF().isZero()) ||
-            ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
-             !CFPf->getValueAPF().isZero()))
-          return replaceInstUsesWith(SI, FalseVal);
-      }
-      // Transform (X une Y) ? Y : X  -> Y
-      if (FCI->getPredicate() == FCmpInst::FCMP_UNE) {
-        // This is not safe in general for floating point:
-        // consider X== -0, Y== +0.
-        // It becomes safe if either operand is a nonzero constant.
-        ConstantFP *CFPt, *CFPf;
-        if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
-              !CFPt->getValueAPF().isZero()) ||
-            ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
-             !CFPf->getValueAPF().isZero()))
-          return replaceInstUsesWith(SI, TrueVal);
-      }
-
       // Canonicalize to use ordered comparisons by swapping the select
       // operands.
       //