[llvm] d34537a - [CVP] Handle use-site conditions in urem folds

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2023-01-13T15:45:34+01:00
New Revision: d34537a732989fe605a9ba127903a263f0e134dd

URL: https://github.com/llvm/llvm-project/commit/d34537a732989fe605a9ba127903a263f0e134dd
DIFF: https://github.com/llvm/llvm-project/commit/d34537a732989fe605a9ba127903a263f0e134dd.diff

LOG: [CVP] Handle use-site conditions in urem folds

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
    llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index 77570221ddd3..c0d109854b27 100644
--- a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -773,11 +773,11 @@ static bool processURem(BinaryOperator *Instr, LazyValueInfo *LVI) {
   assert(Instr->getOpcode() == Instruction::URem);
   assert(!Instr->getType()->isVectorTy());
 
-  Value *X = Instr->getOperand(0);
-  Value *Y = Instr->getOperand(1);
+  const Use &X = Instr->getOperandUse(0);
+  const Use &Y = Instr->getOperandUse(1);
 
-  ConstantRange XCR = LVI->getConstantRange(X, Instr);
-  ConstantRange YCR = LVI->getConstantRange(Y, Instr);
+  ConstantRange XCR = LVI->getConstantRangeAtUse(X);
+  ConstantRange YCR = LVI->getConstantRangeAtUse(Y);
 
   // X u% Y -> X  iff X u< Y
   if (XCR.icmp(ICmpInst::ICMP_ULT, YCR)) {
@@ -819,10 +819,11 @@ static bool processURem(BinaryOperator *Instr, LazyValueInfo *LVI) {
   IRBuilder<> B(Instr);
   // NOTE: this transformation introduces two uses of X,
   //       but it may be undef so we must freeze it first.
-  X = B.CreateFreeze(X, X->getName() + ".frozen");
-  auto *AdjX = B.CreateNUWSub(X, Y, Instr->getName() + ".urem");
-  auto *Cmp = B.CreateICmp(ICmpInst::ICMP_ULT, X, Y, Instr->getName() + ".cmp");
-  auto *ExpandedURem = B.CreateSelect(Cmp, X, AdjX);
+  Value *FrozenX = B.CreateFreeze(X, X->getName() + ".frozen");
+  auto *AdjX = B.CreateNUWSub(FrozenX, Y, Instr->getName() + ".urem");
+  auto *Cmp =
+      B.CreateICmp(ICmpInst::ICMP_ULT, FrozenX, Y, Instr->getName() + ".cmp");
+  auto *ExpandedURem = B.CreateSelect(Cmp, FrozenX, AdjX);
   ExpandedURem->takeName(Instr);
   Instr->replaceAllUsesWith(ExpandedURem);
   Instr->eraseFromParent();

diff  --git a/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll b/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll
index 534413ec4d64..ffa09abf8756 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll
@@ -301,9 +301,8 @@ exit:
 
 define i16 @urem_elide(i16 %x) {
 ; CHECK-LABEL: @urem_elide(
-; CHECK-NEXT:    [[UREM:%.*]] = urem i16 [[X:%.*]], 42
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i16 [[X]], 42
-; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP]], i16 [[UREM]], i16 24
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i16 [[X:%.*]], 42
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP]], i16 [[X]], i16 24
 ; CHECK-NEXT:    ret i16 [[SEL]]
 ;
   %urem = urem i16 %x, 42
@@ -314,7 +313,10 @@ define i16 @urem_elide(i16 %x) {
 
 define i16 @urem_expand(i16 %x) {
 ; CHECK-LABEL: @urem_expand(
-; CHECK-NEXT:    [[UREM:%.*]] = urem i16 [[X:%.*]], 42
+; CHECK-NEXT:    [[X_FROZEN:%.*]] = freeze i16 [[X:%.*]]
+; CHECK-NEXT:    [[UREM_UREM:%.*]] = sub nuw i16 [[X_FROZEN]], 42
+; CHECK-NEXT:    [[UREM_CMP:%.*]] = icmp ult i16 [[X_FROZEN]], 42
+; CHECK-NEXT:    [[UREM:%.*]] = select i1 [[UREM_CMP]], i16 [[X_FROZEN]], i16 [[UREM_UREM]]
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i16 [[X]], 84
 ; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP]], i16 [[UREM]], i16 24
 ; CHECK-NEXT:    ret i16 [[SEL]]