[ConstraintElim] Add tests for llvm#78621.

Tests with umin where the result may be poison for
llvm#78621.

(cherry picked from commit c83180c)

llvm/test/Transforms/ConstraintElimination/umin-result-may-be-poison.ll

@@ -0,0 +1,60 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -p constraint-elimination -S %s | FileCheck %s
+
+; Tests for https://github.com/llvm/llvm-project/issues/78621.
+
+define i1 @umin_not_used(i32 %arg) {
+; CHECK-LABEL: define i1 @umin_not_used(
+; CHECK-SAME: i32 [[ARG:%.*]]) {
+; CHECK-NEXT:    [[SHL:%.*]] = shl nuw nsw i32 [[ARG]], 3
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @llvm.umin.i32(i32 [[SHL]], i32 80)
+; CHECK-NEXT:    [[CMP2:%.*]] = shl nuw nsw i32 [[ARG]], 3
+; CHECK-NEXT:    ret i1 false
+;
+  %icmp = icmp slt i32 %arg, 0
+  %shl = shl nuw nsw i32 %arg, 3
+  call i32 @llvm.umin.i32(i32 %shl, i32 80)
+  %cmp2 = shl nuw nsw i32 %arg, 3
+  ret i1 %icmp
+}
+
+define i1 @umin_poison_is_UB_via_call(i32 %arg) {
+; CHECK-LABEL: define i1 @umin_poison_is_UB_via_call(
+; CHECK-SAME: i32 [[ARG:%.*]]) {
+; CHECK-NEXT:    [[SHL:%.*]] = shl nuw nsw i32 [[ARG]], 3
+; CHECK-NEXT:    [[MIN:%.*]] = call i32 @llvm.umin.i32(i32 [[SHL]], i32 80)
+; CHECK-NEXT:    call void @noundef(i32 noundef [[MIN]])
+; CHECK-NEXT:    [[CMP2:%.*]] = shl nuw nsw i32 [[ARG]], 3
+; CHECK-NEXT:    ret i1 false
+;
+  %icmp = icmp slt i32 %arg, 0
+  %shl = shl nuw nsw i32 %arg, 3
+  %min = call i32 @llvm.umin.i32(i32 %shl, i32 80)
+  call void @noundef(i32 noundef %min)
+  %cmp2 = shl nuw nsw i32 %arg, 3
+  ret i1 %icmp
+}
+
+define i1 @umin_poison_call_before_UB(i32 %arg) {
+; CHECK-LABEL: define i1 @umin_poison_call_before_UB(
+; CHECK-SAME: i32 [[ARG:%.*]]) {
+; CHECK-NEXT:    [[SHL:%.*]] = shl nuw nsw i32 [[ARG]], 3
+; CHECK-NEXT:    [[MIN:%.*]] = call i32 @llvm.umin.i32(i32 [[SHL]], i32 80)
+; CHECK-NEXT:    call void @fn()
+; CHECK-NEXT:    call void @noundef(i32 noundef [[MIN]])
+; CHECK-NEXT:    [[CMP2:%.*]] = shl nuw nsw i32 [[ARG]], 3
+; CHECK-NEXT:    ret i1 false
+;
+  %icmp = icmp slt i32 %arg, 0
+  %shl = shl nuw nsw i32 %arg, 3
+  %min = call i32 @llvm.umin.i32(i32 %shl, i32 80)
+  call void @fn()
+  call void @noundef(i32 noundef %min)
+  %cmp2 = shl nuw nsw i32 %arg, 3
+  ret i1 %icmp
+}
+
+declare i32 @llvm.umin.i32(i32, i32) #0
+
+declare void @noundef(i32 noundef)
+declare void @fn()