[PATCH] D155958: [NFC][ValueTracking]: Remove redundant computeKnownBits call for LoadInst in isKnownNonZero

[Dhruv Chawla via Phabricator via llvm-commits]

0xdc03 created this revision.
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Herald added subscribers: foad, StephenFan, hiraditya.
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For load instructions, computeKnownBits only checks the range metadata.
This check is already present in isKnownNonZero, so there is no need to
fall through to computeKnownBits.

This change gives a speed improvement of 0.18%:
https://llvm-compile-time-tracker.com/compare.php?from=3c6ed559e5274307995586c1499a2c8e4e0276a0&to=78b462d8c4ae079638b728c6446da5999c4ee9f8&stat=instructions:u


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D155958

Files:
  llvm/lib/Analysis/ValueTracking.cpp


Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -2791,6 +2791,9 @@
     return isKnownNonZero(I->getOperand(0), Depth, Q) &&
            isGuaranteedNotToBePoison(I->getOperand(0), Q.AC, Q.CxtI, Q.DT,
                                      Depth);
+  case Instruction::Load:
+    // Already checked above (see range metadata handling).
+    return false;
   case Instruction::Call:
     if (auto *II = dyn_cast<IntrinsicInst>(I)) {
       switch (II->getIntrinsicID()) {


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