[SCCP] Infer nneg on existing zext (#72143)

This patch infers `nneg` flags for existing zext instructions in SCCP. Similar patch: #72052

Author: dtcxzyw

llvm/lib/Transforms/Utils/SCCPSolver.cpp

@@ -107,9 +107,7 @@ bool SCCPSolver::tryToReplaceWithConstant(Value *V) {
 static bool refineInstruction(SCCPSolver &Solver,
  const SmallPtrSetImpl<Value *> &InsertedValues,
  Instruction &Inst) {
- if (!isa<OverflowingBinaryOperator>(Inst))
- return false;
-
+ bool Changed = false;
  auto GetRange = [&Solver, &InsertedValues](Value *Op) {
  if (auto *Const = dyn_cast<ConstantInt>(Op))
  return ConstantRange(Const->getValue());
@@ -120,23 +118,32 @@ static bool refineInstruction(SCCPSolver &Solver,
  return getConstantRange(Solver.getLatticeValueFor(Op), Op->getType(),
  /*UndefAllowed=*/false);
  };
- auto RangeA = GetRange(Inst.getOperand(0));
- auto RangeB = GetRange(Inst.getOperand(1));
- bool Changed = false;
- if (!Inst.hasNoUnsignedWrap()) {
- auto NUWRange = ConstantRange::makeGuaranteedNoWrapRegion(
- Instruction::BinaryOps(Inst.getOpcode()), RangeB,
- OverflowingBinaryOperator::NoUnsignedWrap);
- if (NUWRange.contains(RangeA)) {
- Inst.setHasNoUnsignedWrap();
- Changed = true;
+
+ if (isa<OverflowingBinaryOperator>(Inst)) {
+ auto RangeA = GetRange(Inst.getOperand(0));
+ auto RangeB = GetRange(Inst.getOperand(1));
+ if (!Inst.hasNoUnsignedWrap()) {
+ auto NUWRange = ConstantRange::makeGuaranteedNoWrapRegion(
+ Instruction::BinaryOps(Inst.getOpcode()), RangeB,
+ OverflowingBinaryOperator::NoUnsignedWrap);
+ if (NUWRange.contains(RangeA)) {
+ Inst.setHasNoUnsignedWrap();
+ Changed = true;
+ }
  }
- }
- if (!Inst.hasNoSignedWrap()) {
- auto NSWRange = ConstantRange::makeGuaranteedNoWrapRegion(
- Instruction::BinaryOps(Inst.getOpcode()), RangeB, OverflowingBinaryOperator::NoSignedWrap);
- if (NSWRange.contains(RangeA)) {
- Inst.setHasNoSignedWrap();
+ if (!Inst.hasNoSignedWrap()) {
+ auto NSWRange = ConstantRange::makeGuaranteedNoWrapRegion(
+ Instruction::BinaryOps(Inst.getOpcode()), RangeB,
+ OverflowingBinaryOperator::NoSignedWrap);
+ if (NSWRange.contains(RangeA)) {
+ Inst.setHasNoSignedWrap();
+ Changed = true;
+ }
+ }
+ } else if (isa<ZExtInst>(Inst) && !Inst.hasNonNeg()) {
+ auto Range = GetRange(Inst.getOperand(0));
+ if (Range.isAllNonNegative()) {
+ Inst.setNonNeg();
  Changed = true;
  }
  }

llvm/test/Transforms/SCCP/ip-ranges-casts.ll

@@ -59,7 +59,7 @@ define i1 @caller1() {
 ; x = [100, 301)
 define internal i1 @f.zext(i32 %x, i32 %y) {
 ; CHECK-LABEL: @f.zext(
-; CHECK-NEXT: [[T_1:%.*]] = zext i32 [[X:%.*]] to i64
+; CHECK-NEXT: [[T_1:%.*]] = zext nneg i32 [[X:%.*]] to i64
 ; CHECK-NEXT: [[C_2:%.*]] = icmp sgt i64 [[T_1]], 299
 ; CHECK-NEXT: [[C_4:%.*]] = icmp slt i64 [[T_1]], 101
 ; CHECK-NEXT: [[RES_1:%.*]] = add nuw nsw i1 false, [[C_2]]

llvm/test/Transforms/SCCP/ipsccp-range-crashes.ll

@@ -174,7 +174,7 @@ define i64 @crash_ctpop(i1 %cond, ptr %addr) {
 ; CHECK: if.else:
 ; CHECK-NEXT: [[LV:%.*]] = load i32, ptr [[ADDR:%.*]], align 8
 ; CHECK-NEXT: [[ANDV:%.*]] = and i32 [[LV]], 16777215
-; CHECK-NEXT: [[TRUNCV:%.*]] = zext i32 [[ANDV]] to i64
+; CHECK-NEXT: [[TRUNCV:%.*]] = zext nneg i32 [[ANDV]] to i64
 ; CHECK-NEXT: [[RES:%.*]] = tail call i64 @llvm.ctpop.i64(i64 [[TRUNCV]])
 ; CHECK-NEXT: ret i64 [[RES]]
 ;