[PATCH] D140405: [CVP] Simplify SRem when constantrange abs(lhs) < abs(rhs)

[luxufan via Phabricator via llvm-commits]

StephenFan updated this revision to Diff 484472.
StephenFan added a comment.

Only simplify LHS.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D140405/new/

https://reviews.llvm.org/D140405

Files:
  llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
  llvm/test/Transforms/CorrelatedValuePropagation/srem.ll


Index: llvm/test/Transforms/CorrelatedValuePropagation/srem.ll
===================================================================
--- llvm/test/Transforms/CorrelatedValuePropagation/srem.ll
+++ llvm/test/Transforms/CorrelatedValuePropagation/srem.ll
@@ -523,8 +523,7 @@
 ; CHECK-NEXT:    [[AND_COND:%.*]] = and i1 [[AND_X]], [[Y_CMP]]
 ; CHECK-NEXT:    br i1 [[AND_COND]], label [[IF_ELSE:%.*]], label [[IF_THEN:%.*]]
 ; CHECK:       if.else:
-; CHECK-NEXT:    [[REM:%.*]] = srem i8 [[X]], [[Y]]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i8 [[REM]], [[X]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i8 [[X]], [[X]]
 ; CHECK-NEXT:    ret void
 ; CHECK:       if.then:
 ; CHECK-NEXT:    ret void
@@ -558,8 +557,7 @@
 ; CHECK-NEXT:    [[AND_COND:%.*]] = and i1 [[AND_X]], [[AND_Y]]
 ; CHECK-NEXT:    br i1 [[AND_COND]], label [[IF_ELSE:%.*]], label [[IF_THEN:%.*]]
 ; CHECK:       if.else:
-; CHECK-NEXT:    [[REM:%.*]] = srem i8 [[X]], [[Y]]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i8 [[REM]], [[X]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i8 [[X]], [[X]]
 ; CHECK-NEXT:    ret void
 ; CHECK:       if.then:
 ; CHECK-NEXT:    ret void
@@ -595,8 +593,7 @@
 ; CHECK-NEXT:    [[AND_COND:%.*]] = and i1 [[AND_X]], [[AND_Y]]
 ; CHECK-NEXT:    br i1 [[AND_COND]], label [[IF_ELSE:%.*]], label [[IF_THEN:%.*]]
 ; CHECK:       if.else:
-; CHECK-NEXT:    [[REM:%.*]] = srem i8 [[X]], [[Y]]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i8 [[REM]], [[X]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i8 [[X]], [[X]]
 ; CHECK-NEXT:    ret void
 ; CHECK:       if.then:
 ; CHECK-NEXT:    ret void
Index: llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -843,6 +843,15 @@
   if (SDI->getType()->isVectorTy())
     return false;
 
+  ConstantRange LCR = LVI->getConstantRange(SDI->getOperand(0), SDI);
+  ConstantRange RCR = LVI->getConstantRange(SDI->getOperand(1), SDI);
+
+  if (LCR.abs().icmp(CmpInst::ICMP_ULT, RCR.abs())) {
+    SDI->replaceAllUsesWith(SDI->getOperand(0));
+    SDI->eraseFromParent();
+    return true;
+  }
+
   struct Operand {
     Value *V;
     Domain D;


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