[InstCombine] add tests for unsigned saturated add; NFC

rotateright · rotateright · commit 3e1193743c43 · 2019-02-17T15:09:41.000Z
We're missing IR canonicalizations for this op as shown in D51929.

llvm-svn: 354219
diff --git a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
@@ -639,6 +639,38 @@ define <2 x i8> @test_vector_ssub_neg_nneg(<2 x i8> %a) {
 
 ; Raw IR tests
 
+define i32 @uadd_sat(i32 %x, i32 %y) {
+; CHECK-LABEL: @uadd_sat(
+; CHECK-NEXT:    [[NOTX:%.*]] = xor i32 [[X:%.*]], -1
+; CHECK-NEXT:    [[A:%.*]] = add i32 [[Y:%.*]], [[X]]
+; CHECK-NEXT:    [[C:%.*]] = icmp ult i32 [[NOTX]], [[Y]]
+; CHECK-NEXT:    [[R:%.*]] = select i1 [[C]], i32 -1, i32 [[A]]
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %notx = xor i32 %x, -1
+  %a = add i32 %y, %x
+  %c = icmp ult i32 %notx, %y
+  %r = select i1 %c, i32 -1, i32 %a
+  ret i32 %r
+}
+
+define i32 @uadd_sat_commute1(i32 %xp, i32 %y) {
+; CHECK-LABEL: @uadd_sat_commute1(
+; CHECK-NEXT:    [[X:%.*]] = urem i32 42, [[XP:%.*]]
+; CHECK-NEXT:    [[NOTX:%.*]] = xor i32 [[X]], -1
+; CHECK-NEXT:    [[A:%.*]] = add i32 [[X]], [[Y:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = icmp ult i32 [[NOTX]], [[Y]]
+; CHECK-NEXT:    [[R:%.*]] = select i1 [[C]], i32 -1, i32 [[A]]
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %x = urem i32 42, %xp ; thwart complexity-based-canonicalization
+  %notx = xor i32 %x, -1
+  %a = add i32 %x, %y
+  %c = icmp ult i32 %notx, %y
+  %r = select i1 %c, i32 -1, i32 %a
+  ret i32 %r
+}
+
 define i32 @uadd_sat_constant(i32 %x) {
 ; CHECK-LABEL: @uadd_sat_constant(
 ; CHECK-NEXT:    [[A:%.*]] = add i32 [[X:%.*]], 42
