ValueTracking: Avoid unnecessary denormal mode lookup for fadd

[arsenm]

The mode was already queried, so don't do it again.

[arsenm]

• ValueTracking: Avoid unnecessary denormal mode lookup for fadd #174272 👈 (View in Graphite)
• ValueTracking: Improve handling of fadd in computeKnownFPClass. #174123
• ValueTracking: Add more baseline tests for computeKnownPPClass of fadd #174122
• main

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[arsenm]

Accidentally posted this in the parent initially

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

@llvm/pr-subscribers-llvm-analysis

Author: Matt Arsenault (arsenm)

Changes

The mode was already queried, so don't do it again.

---

Full diff: https://github.com/llvm/llvm-project/pull/174272.diff

1 Files Affected:

• (modified) llvm/lib/Analysis/ValueTracking.cpp (+4-8)

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index d7d5daa348412..6b5792227a371 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4728,12 +4728,6 @@ Intrinsic::ID llvm::getIntrinsicForCallSite(const CallBase &CB,
   return Intrinsic::not_intrinsic;
 }
 
-static bool outputDenormalIsIEEEOrPosZero(const Function &F, const Type *Ty) {
-  Ty = Ty->getScalarType();
-  DenormalMode Mode = F.getDenormalMode(Ty->getFltSemantics());
-  return Mode.Output == DenormalMode::IEEE ||
-         Mode.Output == DenormalMode::PositiveZero;
-}
 /// Given an exploded icmp instruction, return true if the comparison only
 /// checks the sign bit. If it only checks the sign bit, set TrueIfSigned if
 /// the result of the comparison is true when the input value is signed.
@@ -5671,7 +5665,8 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
         if ((KnownLHS.isKnownNeverLogicalNegZero(Mode) ||
              KnownRHS.isKnownNeverLogicalNegZero(Mode)) &&
             // Make sure output negative denormal can't flush to -0
-            outputDenormalIsIEEEOrPosZero(*F, Op->getType()))
+            (Mode.Output == DenormalMode::IEEE ||
+             Mode.Output == DenormalMode::PositiveZero))
           Known.knownNot(fcNegZero);
       } else {
         if (!F)
@@ -5685,7 +5680,8 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
         if ((KnownLHS.isKnownNeverLogicalNegZero(Mode) ||
              KnownRHS.isKnownNeverLogicalPosZero(Mode)) &&
             // Make sure output negative denormal can't flush to -0
-            outputDenormalIsIEEEOrPosZero(*F, Op->getType()))
+            (Mode.Output == DenormalMode::IEEE ||
+             Mode.Output == DenormalMode::PositiveZero))
           Known.knownNot(fcNegZero);
       }
     }