[InstSimplify] Add tests for saturating add/sub + icmp; NFC

If a saturating add/sub with a constant operand is compared to
another constant, we should be able to determine that the condition
is always true/false in some cases (but currently don't).

llvm-svn: 349261

1 files changed, 165 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstSimplify/saturating-add-sub.ll b/llvm/test/Transforms/InstSimplify/saturating-add-sub.ll
index 86be08fdaed..d16ed4256f6 100644
--- a/llvm/test/Transforms/InstSimplify/saturating-add-sub.ll
+++ b/llvm/test/Transforms/InstSimplify/saturating-add-sub.ll
@@ -406,3 +406,168 @@ define <2 x i8> @ssub_vector_same(<2 x i8> %a) {
   ret <2 x i8> %y6v
 }
 
+define i1 @uadd_icmp_known(i8 %a) {
+; CHECK-LABEL: @uadd_icmp_known(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.uadd.sat.i8(i8 [[A:%.*]], i8 10)
+; CHECK-NEXT:    [[C:%.*]] = icmp uge i8 [[B]], 10
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.uadd.sat.i8(i8 %a, i8 10)
+  %c = icmp uge i8 %b, 10
+  ret i1 %c
+}
+
+define i1 @uadd_icmp_unknown(i8 %a) {
+; CHECK-LABEL: @uadd_icmp_unknown(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.uadd.sat.i8(i8 [[A:%.*]], i8 10)
+; CHECK-NEXT:    [[C:%.*]] = icmp ugt i8 [[B]], 10
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.uadd.sat.i8(i8 %a, i8 10)
+  %c = icmp ugt i8 %b, 10
+  ret i1 %c
+}
+
+define i1 @sadd_icmp_pos_known(i8 %a) {
+; CHECK-LABEL: @sadd_icmp_pos_known(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.sadd.sat.i8(i8 [[A:%.*]], i8 10)
+; CHECK-NEXT:    [[C:%.*]] = icmp sge i8 [[B]], -118
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.sadd.sat.i8(i8 %a, i8 10)
+  %c = icmp sge i8 %b, -118
+  ret i1 %c
+}
+
+define i1 @sadd_icmp_pos_unknown(i8 %a) {
+; CHECK-LABEL: @sadd_icmp_pos_unknown(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.sadd.sat.i8(i8 [[A:%.*]], i8 10)
+; CHECK-NEXT:    [[C:%.*]] = icmp sgt i8 [[B]], -118
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.sadd.sat.i8(i8 %a, i8 10)
+  %c = icmp sgt i8 %b, -118
+  ret i1 %c
+}
+
+define i1 @sadd_icmp_neg_known(i8 %a) {
+; CHECK-LABEL: @sadd_icmp_neg_known(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.sadd.sat.i8(i8 [[A:%.*]], i8 -10)
+; CHECK-NEXT:    [[C:%.*]] = icmp sle i8 [[B]], 117
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.sadd.sat.i8(i8 %a, i8 -10)
+  %c = icmp sle i8 %b, 117
+  ret i1 %c
+}
+
+define i1 @sadd_icmp_neg_unknown(i8 %a) {
+; CHECK-LABEL: @sadd_icmp_neg_unknown(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.sadd.sat.i8(i8 [[A:%.*]], i8 -10)
+; CHECK-NEXT:    [[C:%.*]] = icmp slt i8 [[B]], 117
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.sadd.sat.i8(i8 %a, i8 -10)
+  %c = icmp slt i8 %b, 117
+  ret i1 %c
+}
+
+define i1 @usub_icmp_op0_known(i8 %a) {
+; CHECK-LABEL: @usub_icmp_op0_known(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.usub.sat.i8(i8 10, i8 [[A:%.*]])
+; CHECK-NEXT:    [[C:%.*]] = icmp ule i8 [[B]], 10
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.usub.sat.i8(i8 10, i8 %a)
+  %c = icmp ule i8 %b, 10
+  ret i1 %c
+}
+
+define i1 @usub_icmp_op0_unknown(i8 %a) {
+; CHECK-LABEL: @usub_icmp_op0_unknown(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.usub.sat.i8(i8 10, i8 [[A:%.*]])
+; CHECK-NEXT:    [[C:%.*]] = icmp ult i8 [[B]], 10
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.usub.sat.i8(i8 10, i8 %a)
+  %c = icmp ult i8 %b, 10
+  ret i1 %c
+}
+
+define i1 @usub_icmp_op1_known(i8 %a) {
+; CHECK-LABEL: @usub_icmp_op1_known(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.usub.sat.i8(i8 [[A:%.*]], i8 10)
+; CHECK-NEXT:    [[C:%.*]] = icmp ule i8 [[B]], -11
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.usub.sat.i8(i8 %a, i8 10)
+  %c = icmp ule i8 %b, 245
+  ret i1 %c
+}
+
+define i1 @usub_icmp_op1_unknown(i8 %a) {
+; CHECK-LABEL: @usub_icmp_op1_unknown(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.usub.sat.i8(i8 [[A:%.*]], i8 10)
+; CHECK-NEXT:    [[C:%.*]] = icmp ult i8 [[B]], -11
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.usub.sat.i8(i8 %a, i8 10)
+  %c = icmp ult i8 %b, 245
+  ret i1 %c
+}
+
+define i1 @ssub_icmp_op0_pos_known(i8 %a) {
+; CHECK-LABEL: @ssub_icmp_op0_pos_known(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.ssub.sat.i8(i8 10, i8 [[A:%.*]])
+; CHECK-NEXT:    [[C:%.*]] = icmp sge i8 [[B]], -117
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.ssub.sat.i8(i8 10, i8 %a)
+  %c = icmp sge i8 %b, -117
+  ret i1 %c
+}
+
+define i1 @ssub_icmp_op0_pos_unknown(i8 %a) {
+; CHECK-LABEL: @ssub_icmp_op0_pos_unknown(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.ssub.sat.i8(i8 10, i8 [[A:%.*]])
+; CHECK-NEXT:    [[C:%.*]] = icmp sgt i8 [[B]], -117
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.ssub.sat.i8(i8 10, i8 %a)
+  %c = icmp sgt i8 %b, -117
+  ret i1 %c
+}
+
+define i1 @ssub_icmp_op0_neg_known(i8 %a) {
+; CHECK-LABEL: @ssub_icmp_op0_neg_known(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.ssub.sat.i8(i8 -10, i8 [[A:%.*]])
+; CHECK-NEXT:    [[C:%.*]] = icmp sle i8 [[B]], 118
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.ssub.sat.i8(i8 -10, i8 %a)
+  %c = icmp sle i8 %b, 118
+  ret i1 %c
+}
+
+define i1 @ssub_icmp_op0_neg_unknown(i8 %a) {
+; CHECK-LABEL: @ssub_icmp_op0_neg_unknown(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.ssub.sat.i8(i8 -10, i8 [[A:%.*]])
+; CHECK-NEXT:    [[C:%.*]] = icmp slt i8 [[B]], 118
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.ssub.sat.i8(i8 -10, i8 %a)
+  %c = icmp slt i8 %b, 118
+  ret i1 %c
+}
+
+; Peculiar case: ssub.sat(0, x) is never signed min.
+define i1 @ssub_icmp_op0_zero(i8 %a) {
+; CHECK-LABEL: @ssub_icmp_op0_zero(
+; CHECK-NEXT:    [[B:%.*]] = call i8 @llvm.ssub.sat.i8(i8 0, i8 [[A:%.*]])
+; CHECK-NEXT:    [[C:%.*]] = icmp ne i8 [[B]], -128
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = call i8 @llvm.ssub.sat.i8(i8 0, i8 %a)
+  %c = icmp ne i8 %b, -128
+  ret i1 %c
+}