Add negative tests.

Author: rkirsling

llvm/test/Transforms/InstCombine/sub-after-sle-is-non-negative.ll

@@ -1,5 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
 ; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+declare void @subroutine(i16)
+
 define void @test_as_arg(i8 %a, i8 %b) {
 ; CHECK-LABEL: define void @test_as_arg(
 ; CHECK-SAME: i8 [[A:%.*]], i8 [[B:%.*]]) {
@@ -26,8 +28,6 @@ cond.end:
   ret void
 }
 
-declare void @subroutine(i16)
-
 define i16 @test_as_retval(i8 %a, i8 %b) {
 ; CHECK-LABEL: define i16 @test_as_retval(
 ; CHECK-SAME: i8 [[A:%.*]], i8 [[B:%.*]]) {
@@ -51,3 +51,53 @@ cond.false:
   %conv = sext i8 %sub to i16
   ret i16 %conv
 }
+
+define void @test_as_arg_neg(i8 %a, i8 %b) {
+; CHECK-LABEL: define void @test_as_arg_neg(
+; CHECK-SAME: i8 [[A:%.*]], i8 [[B:%.*]]) {
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i8 [[A]], [[B]]
+; CHECK-NEXT:    br i1 [[CMP]], label %[[COND_END:.*]], label %[[COND_FALSE:.*]]
+; CHECK:       [[COND_FALSE]]:
+; CHECK-NEXT:    [[SUB:%.*]] = sub nsw i8 [[B]], [[A]]
+; CHECK-NEXT:    [[CONV:%.*]] = sext i8 [[SUB]] to i16
+; CHECK-NEXT:    call void @subroutine(i16 [[CONV]])
+; CHECK-NEXT:    br label %[[COND_END]]
+; CHECK:       [[COND_END]]:
+; CHECK-NEXT:    ret void
+;
+  %cmp = icmp slt i8 %a, %b
+  br i1 %cmp, label %cond.end, label %cond.false
+
+cond.false:
+  %sub = sub nsw i8 %b, %a
+  %conv = sext i8 %sub to i16
+  call void @subroutine(i16 %conv)
+  br label %cond.end
+
+cond.end:
+  ret void
+}
+
+define i16 @test_as_retval_neg(i8 %a, i8 %b) {
+; CHECK-LABEL: define i16 @test_as_retval_neg(
+; CHECK-SAME: i8 [[A:%.*]], i8 [[B:%.*]]) {
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i8 [[A]], [[B]]
+; CHECK-NEXT:    br i1 [[CMP]], label %[[COND_TRUE:.*]], label %[[COND_FALSE:.*]]
+; CHECK:       [[COND_TRUE]]:
+; CHECK-NEXT:    ret i16 0
+; CHECK:       [[COND_FALSE]]:
+; CHECK-NEXT:    [[SUB:%.*]] = sub nsw i8 [[B]], [[A]]
+; CHECK-NEXT:    [[CONV:%.*]] = sext i8 [[SUB]] to i16
+; CHECK-NEXT:    ret i16 [[CONV]]
+;
+  %cmp = icmp slt i8 %a, %b
+  br i1 %cmp, label %cond.true, label %cond.false
+
+cond.true:
+  ret i16 0
+
+cond.false:
+  %sub = sub nsw i8 %b, %a
+  %conv = sext i8 %sub to i16
+  ret i16 %conv
+}