[llvm] f677d3f - [ConstraintElimination] Allow pointer types in tightenBoundUsingNe (#223215)

[via llvm-commits]

Author: Alina Sbirlea
Date: 2026-09-21T15:53:43-07:00
New Revision: f677d3f38f45f318df47d5b5dd59a20c71d6a9bc

URL: https://github.com/llvm/llvm-project/commit/f677d3f38f45f318df47d5b5dd59a20c71d6a9bc
DIFF: https://github.com/llvm/llvm-project/commit/f677d3f38f45f318df47d5b5dd59a20c71d6a9bc.diff

LOG: [ConstraintElimination] Allow pointer types in tightenBoundUsingNe (#223215)

Allow pointer types in ConstraintInfo::tightenBoundUsingNe() for the
unsigned system. When A != B is known and the system already implies A
u>= B, tighten the bound to strict inequality A u> B (symmetrically, A
u<= B becomes A u< B).

Added lit tests in
llvm/test/Transforms/ConstraintElimination/pointer-tighten-ne.ll.

Added: 
    llvm/test/Transforms/ConstraintElimination/pointer-tighten-ne.ll

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

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
index daf8167224628..46b39ff77accc 100644
--- a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
@@ -2090,7 +2090,7 @@ void ConstraintInfo::addFact(CmpInst::Predicate Pred, Value *A, Value *B,
 void ConstraintInfo::tightenBoundUsingNe(
     Value *A, Value *B, unsigned NumIn, unsigned NumOut,
     SmallVectorImpl<StackEntry> &DFSInStack) {
-  if (!A->getType()->isIntegerTy())
+  if (!A->getType()->isIntOrPtrTy())
     return;
 
   for (bool IsSigned : {false, true}) {

diff  --git a/llvm/test/Transforms/ConstraintElimination/pointer-tighten-ne.ll b/llvm/test/Transforms/ConstraintElimination/pointer-tighten-ne.ll
new file mode 100644
index 0000000000000..da177135bf592
--- /dev/null
+++ b/llvm/test/Transforms/ConstraintElimination/pointer-tighten-ne.ll
@@ -0,0 +1,40 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes=constraint-elimination -S %s | FileCheck %s
+
+declare void @llvm.assume(i1 noundef)
+
+; Pointer inequality tightening: a u>= b and a != b implies strict a u> b.
+define i1 @test_ptr_tighten_uge_ne(ptr %a, ptr %b) {
+; CHECK-LABEL: define i1 @test_ptr_tighten_uge_ne(
+; CHECK-SAME: ptr [[A:%.*]], ptr [[B:%.*]]) {
+; CHECK-NEXT:    [[C1:%.*]] = icmp uge ptr [[A]], [[B]]
+; CHECK-NEXT:    call void @llvm.assume(i1 [[C1]])
+; CHECK-NEXT:    [[C2:%.*]] = icmp ne ptr [[A]], [[B]]
+; CHECK-NEXT:    call void @llvm.assume(i1 [[C2]])
+; CHECK-NEXT:    ret i1 true
+;
+  %c1 = icmp uge ptr %a, %b
+  call void @llvm.assume(i1 %c1)
+  %c2 = icmp ne ptr %a, %b
+  call void @llvm.assume(i1 %c2)
+  %check = icmp ugt ptr %a, %b
+  ret i1 %check
+}
+
+; Pointer inequality tightening: a u<= b and a != b implies strict a u< b.
+define i1 @test_ptr_tighten_ule_ne(ptr %a, ptr %b) {
+; CHECK-LABEL: define i1 @test_ptr_tighten_ule_ne(
+; CHECK-SAME: ptr [[A:%.*]], ptr [[B:%.*]]) {
+; CHECK-NEXT:    [[C1:%.*]] = icmp ule ptr [[A]], [[B]]
+; CHECK-NEXT:    call void @llvm.assume(i1 [[C1]])
+; CHECK-NEXT:    [[C2:%.*]] = icmp ne ptr [[A]], [[B]]
+; CHECK-NEXT:    call void @llvm.assume(i1 [[C2]])
+; CHECK-NEXT:    ret i1 true
+;
+  %c1 = icmp ule ptr %a, %b
+  call void @llvm.assume(i1 %c1)
+  %c2 = icmp ne ptr %a, %b
+  call void @llvm.assume(i1 %c2)
+  %check = icmp ult ptr %a, %b
+  ret i1 %check
+}