[SCCP] Infer nneg on existing zext

[dtcxzyw]

This patch infers nneg flags for existing zext instructions in SCCP.

Similar patch: #72052

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

@llvm/pr-subscribers-function-specialization

Author: Yingwei Zheng (dtcxzyw)

Changes

This patch infers nneg flags for existing zext instructions in SCCP.

Similar patch: #72052

---

Full diff: https://github.com/llvm/llvm-project/pull/72143.diff

3 Files Affected:

• (modified) llvm/lib/Transforms/Utils/SCCPSolver.cpp (+26-19)
• (modified) llvm/test/Transforms/SCCP/ip-ranges-casts.ll (+1-1)
• (modified) llvm/test/Transforms/SCCP/ipsccp-range-crashes.ll (+1-1)

diff --git a/llvm/lib/Transforms/Utils/SCCPSolver.cpp b/llvm/lib/Transforms/Utils/SCCPSolver.cpp
index ea8425c5d5ddc15..dac10c2a8baf9e1 100644
--- a/llvm/lib/Transforms/Utils/SCCPSolver.cpp
+++ b/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;
     }
   }
diff --git a/llvm/test/Transforms/SCCP/ip-ranges-casts.ll b/llvm/test/Transforms/SCCP/ip-ranges-casts.ll
index 6fbcb5d166dce7b..b97b3a0c4581689 100644
--- a/llvm/test/Transforms/SCCP/ip-ranges-casts.ll
+++ b/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]]
diff --git a/llvm/test/Transforms/SCCP/ipsccp-range-crashes.ll b/llvm/test/Transforms/SCCP/ipsccp-range-crashes.ll
index 99d728aba7086ed..0cc14d66402ad18 100644
--- a/llvm/test/Transforms/SCCP/ipsccp-range-crashes.ll
+++ b/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]]
 ;

[nikic]

LGTM