[PATCH] D100408: [ValueTracking][InstSimplify] improve efficiency for detecting non-zero value

[Sanjay Patel via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
spatel marked an inline comment as done.
Closed by commit rG7ef2c68a3d24: [InstSimplify] improve efficiency for detecting non-zero value (authored by spatel).

Changed prior to commit:
  https://reviews.llvm.org/D100408?vs=337227&id=337429#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D100408/new/

https://reviews.llvm.org/D100408

Files:
  llvm/lib/Analysis/InstructionSimplify.cpp


Index: llvm/lib/Analysis/InstructionSimplify.cpp
===================================================================
--- llvm/lib/Analysis/InstructionSimplify.cpp
+++ llvm/lib/Analysis/InstructionSimplify.cpp
@@ -3432,6 +3432,8 @@
   if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q))
     return V;
 
+  // TODO: Sink/common this with other potentially expensive calls that use
+  //       ValueTracking? See comment below for isKnownNonEqual().
   if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q))
     return V;
 
@@ -3637,7 +3639,9 @@
   }
 
   // icmp eq|ne X, Y -> false|true if X != Y
-  if (ICmpInst::isEquality(Pred) &&
+  // This is potentially expensive, and we have already computedKnownBits for
+  // compares with 0 above here, so only try this for a non-zero compare.
+  if (ICmpInst::isEquality(Pred) && !match(RHS, m_Zero()) &&
       isKnownNonEqual(LHS, RHS, Q.DL, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) {
     return Pred == ICmpInst::ICMP_NE ? getTrue(ITy) : getFalse(ITy);
   }


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