[llvm] aa60d16 - [CVP] Add a cl::opt for canonicalization of signed relational comparisons

[Artur Pilipenko via llvm-commits]

Author: Artur Pilipenko
Date: 2021-11-24T13:52:38-08:00
New Revision: aa60d169ea62ee375910e684d20932519fe3f64f

URL: https://github.com/llvm/llvm-project/commit/aa60d169ea62ee375910e684d20932519fe3f64f
DIFF: https://github.com/llvm/llvm-project/commit/aa60d169ea62ee375910e684d20932519fe3f64f.diff

LOG: [CVP] Add a cl::opt for canonicalization of signed relational comparisons

This canonicalization breaks the ability to discard checks in some cases.
Add a command line option to disable it. This option is on by default,
so the change is NFC.

See for details:
https://reviews.llvm.org/D112895#3149487

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index d1ae35cc17ab2..6d6097c9ece10 100644
--- a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -52,6 +52,11 @@ using namespace llvm;
 
 #define DEBUG_TYPE "correlated-value-propagation"
 
+static cl::opt<bool> CanonicalizeICmpPredicatesToUnsigned(
+    "canonicalize-icmp-predicates-to-unsigned", cl::init(true), cl::Hidden,
+    cl::desc("Enables canonicalization of signed relational predicates to "
+             "unsigned (e.g. sgt => ugt)"));
+
 STATISTIC(NumPhis,      "Number of phis propagated");
 STATISTIC(NumPhiCommon, "Number of phis deleted via common incoming value");
 STATISTIC(NumSelects,   "Number of selects propagated");
@@ -297,6 +302,9 @@ static bool processMemAccess(Instruction *I, LazyValueInfo *LVI) {
 }
 
 static bool processICmp(ICmpInst *Cmp, LazyValueInfo *LVI) {
+  if (!CanonicalizeICmpPredicatesToUnsigned)
+    return false;
+
   // Only for signed relational comparisons of scalar integers.
   if (Cmp->getType()->isVectorTy() ||
       !Cmp->getOperand(0)->getType()->isIntegerTy())