[ConstraintElim] Add tests for llvm.abs

[alexander-shaposhnikov]

This is a preparation for #73189

Test plan: ninja check-all

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Alexander Shaposhnikov (alexander-shaposhnikov)

Changes

This is a preparation for #73189

Test plan: ninja check-all

---

Full diff: https://github.com/llvm/llvm-project/pull/76374.diff

1 Files Affected:

• (added) llvm/test/Transforms/ConstraintElimination/abs.ll (+64)

diff --git a/llvm/test/Transforms/ConstraintElimination/abs.ll b/llvm/test/Transforms/ConstraintElimination/abs.ll
new file mode 100644
index 00000000000000..5d788996767c4c
--- /dev/null
+++ b/llvm/test/Transforms/ConstraintElimination/abs.ll
@@ -0,0 +1,64 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -passes=constraint-elimination -S %s | FileCheck %s
+
+define i1 @abs_int_min_is_not_poison(i32 %arg) {
+; CHECK-LABEL: define i1 @abs_int_min_is_not_poison(
+; CHECK-SAME: i32 [[ARG:%.*]]) {
+; CHECK-NEXT:    [[ABS:%.*]] = tail call i32 @llvm.abs.i32(i32 [[ARG]], i1 false)
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sge i32 [[ABS]], [[ARG]]
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = tail call i32 @llvm.abs.i32(i32 %arg, i1 false)
+  %cmp = icmp sge i32 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @abs_int_min_is_poison(i32 %arg) {
+; CHECK-LABEL: define i1 @abs_int_min_is_poison(
+; CHECK-SAME: i32 [[ARG:%.*]]) {
+; CHECK-NEXT:    [[ABS:%.*]] = tail call i32 @llvm.abs.i32(i32 [[ARG]], i1 true)
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sge i32 [[ABS]], [[ARG]]
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = tail call i32 @llvm.abs.i32(i32 %arg, i1 true)
+  %cmp = icmp sge i32 %abs, %arg
+  ret i1 %cmp
+}
+
+define i1 @abs_plus_one(i32 %arg) {
+; CHECK-LABEL: define i1 @abs_plus_one(
+; CHECK-SAME: i32 [[ARG:%.*]]) {
+; CHECK-NEXT:    [[ABS:%.*]] = tail call i32 @llvm.abs.i32(i32 [[ARG]], i1 true)
+; CHECK-NEXT:    [[ABS_PLUS_ONE:%.*]] = add nsw i32 [[ABS]], 1
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sge i32 [[ABS_PLUS_ONE]], [[ARG]]
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = tail call i32 @llvm.abs.i32(i32 %arg, i1 true)
+  %abs_plus_one = add nsw i32 %abs, 1
+  %cmp = icmp sge i32 %abs_plus_one, %arg
+  ret i1 %cmp
+}
+
+define i1 @abs_constant_negative_arg() {
+; CHECK-LABEL: define i1 @abs_constant_negative_arg() {
+; CHECK-NEXT:    [[ABS:%.*]] = tail call i32 @llvm.abs.i32(i32 -3, i1 false)
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sge i32 [[ABS]], 3
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = tail call i32 @llvm.abs.i32(i32 -3, i1 false)
+  %cmp = icmp sge i32 %abs, 3
+  ret i1 %cmp
+}
+
+define i1 @abs_constant_positive_arg() {
+; CHECK-LABEL: define i1 @abs_constant_positive_arg() {
+; CHECK-NEXT:    [[ABS:%.*]] = tail call i32 @llvm.abs.i32(i32 3, i1 false)
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sge i32 [[ABS]], 3
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %abs = tail call i32 @llvm.abs.i32(i32 3, i1 false)
+  %cmp = icmp sge i32 %abs, 3
+  ret i1 %cmp
+}
+
+declare i32 @llvm.abs.i32(i32, i1 immarg)

[fhahn]

Thanks for putting up the tests as separate PR! Could you also add tests with predicates other than sge (including some that cannot be simplified) and some unsigned ones as well?

[alexander-shaposhnikov]

done

[fhahn]

Thanks for the update! I think the last case missing is one where a compare gets simplified to false.

[fhahn]

typo: eual -> equal.

[alexander-shaposhnikov]

Fixed

[alexander-shaposhnikov]

Address comments

[fhahn]

LGTM, thanks!