From 15abd74de7d6c552070f1ee51361d524c5d4d275 Mon Sep 17 00:00:00 2001
From: Nikita Popov <nikita.ppv@gmail.com>
Date: Mon, 8 Apr 2019 20:02:47 +0000
Subject: [PATCH] [InstCombine] Add more tests for signed saturing math
 overflow; NFC

Overflow conditions for sadd.sat and ssub.sat which can be determined
based on constant ranges, but not necessarily known bits.

llvm-svn: 357938
---
 .../Transforms/InstCombine/saturating-add-sub.ll   | 117 ++++++++++++++++++++-
 1 file changed, 115 insertions(+), 2 deletions(-)

diff --git a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
index 3ab5008..41203c4 100644
--- a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
+++ b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
@@ -375,8 +375,8 @@ define i8 @test_scalar_uadd_urem_may_ov(i8 %a) {
 }
 
 ; We have a constant range for the LHS, but only known bits for the RHS
-define i8 @test_scalar_uadd_urem_known_bits(i8 %a, i8 %b) {
-; CHECK-LABEL: @test_scalar_uadd_urem_known_bits(
+define i8 @test_scalar_uadd_udiv_known_bits(i8 %a, i8 %b) {
+; CHECK-LABEL: @test_scalar_uadd_udiv_known_bits(
 ; CHECK-NEXT:    [[AA:%.*]] = udiv i8 -66, [[A:%.*]]
 ; CHECK-NEXT:    [[BB:%.*]] = and i8 [[B:%.*]], 63
 ; CHECK-NEXT:    [[R:%.*]] = add nuw i8 [[AA]], [[BB]]
@@ -388,6 +388,41 @@ define i8 @test_scalar_uadd_urem_known_bits(i8 %a, i8 %b) {
   ret i8 %r
 }
 
+define i8 @test_scalar_sadd_srem_no_ov(i8 %a) {
+; CHECK-LABEL: @test_scalar_sadd_srem_no_ov(
+; CHECK-NEXT:    [[B:%.*]] = srem i8 [[A:%.*]], 100
+; CHECK-NEXT:    [[R:%.*]] = call i8 @llvm.sadd.sat.i8(i8 [[B]], i8 28)
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %b = srem i8 %a, 100
+  %r = call i8 @llvm.sadd.sat.i8(i8 %b, i8 28)
+  ret i8 %r
+}
+
+define i8 @test_scalar_sadd_srem_may_ov(i8 %a) {
+; CHECK-LABEL: @test_scalar_sadd_srem_may_ov(
+; CHECK-NEXT:    [[B:%.*]] = srem i8 [[A:%.*]], 100
+; CHECK-NEXT:    [[R:%.*]] = call i8 @llvm.sadd.sat.i8(i8 [[B]], i8 29)
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %b = srem i8 %a, 100
+  %r = call i8 @llvm.sadd.sat.i8(i8 %b, i8 29)
+  ret i8 %r
+}
+
+define i8 @test_scalar_sadd_srem_and_no_ov(i8 %a, i8 %b) {
+; CHECK-LABEL: @test_scalar_sadd_srem_and_no_ov(
+; CHECK-NEXT:    [[AA:%.*]] = srem i8 [[A:%.*]], 100
+; CHECK-NEXT:    [[BB:%.*]] = and i8 [[B:%.*]], 15
+; CHECK-NEXT:    [[R:%.*]] = call i8 @llvm.sadd.sat.i8(i8 [[AA]], i8 [[BB]])
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %aa = srem i8 %a, 100
+  %bb = and i8 %b, 15
+  %r = call i8 @llvm.sadd.sat.i8(i8 %aa, i8 %bb)
+  ret i8 %r
+}
+
 ;
 ; Saturating subtraction.
 ;
@@ -889,6 +924,84 @@ define <2 x i8> @test_vector_usub_add_nuw_no_ov_nonsplat3(<2 x i8> %a) {
   ret <2 x i8> %r
 }
 
+define i8 @test_scalar_ssub_add_nsw_no_ov(i8 %a, i8 %b) {
+; CHECK-LABEL: @test_scalar_ssub_add_nsw_no_ov(
+; CHECK-NEXT:    [[AA:%.*]] = add nsw i8 [[A:%.*]], 7
+; CHECK-NEXT:    [[BB:%.*]] = and i8 [[B:%.*]], 7
+; CHECK-NEXT:    [[R:%.*]] = call i8 @llvm.ssub.sat.i8(i8 [[AA]], i8 [[BB]])
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %aa = add nsw i8 %a, 7
+  %bb = and i8 %b, 7
+  %r = call i8 @llvm.ssub.sat.i8(i8 %aa, i8 %bb)
+  ret i8 %r
+}
+
+define i8 @test_scalar_ssub_add_nsw_may_ov(i8 %a, i8 %b) {
+; CHECK-LABEL: @test_scalar_ssub_add_nsw_may_ov(
+; CHECK-NEXT:    [[AA:%.*]] = add nsw i8 [[A:%.*]], 6
+; CHECK-NEXT:    [[BB:%.*]] = and i8 [[B:%.*]], 7
+; CHECK-NEXT:    [[R:%.*]] = call i8 @llvm.ssub.sat.i8(i8 [[AA]], i8 [[BB]])
+; CHECK-NEXT:    ret i8 [[R]]
+;
+  %aa = add nsw i8 %a, 6
+  %bb = and i8 %b, 7
+  %r = call i8 @llvm.ssub.sat.i8(i8 %aa, i8 %bb)
+  ret i8 %r
+}
+
+define <2 x i8> @test_vector_ssub_add_nsw_no_ov_splat(<2 x i8> %a, <2 x i8> %b) {
+; CHECK-LABEL: @test_vector_ssub_add_nsw_no_ov_splat(
+; CHECK-NEXT:    [[AA:%.*]] = add nsw <2 x i8> [[A:%.*]], <i8 7, i8 7>
+; CHECK-NEXT:    [[BB:%.*]] = and <2 x i8> [[B:%.*]], <i8 7, i8 7>
+; CHECK-NEXT:    [[R:%.*]] = call <2 x i8> @llvm.ssub.sat.v2i8(<2 x i8> [[AA]], <2 x i8> [[BB]])
+; CHECK-NEXT:    ret <2 x i8> [[R]]
+;
+  %aa = add nsw <2 x i8> %a, <i8 7, i8 7>
+  %bb = and <2 x i8> %b, <i8 7, i8 7>
+  %r = call <2 x i8> @llvm.ssub.sat.v2i8(<2 x i8> %aa, <2 x i8> %bb)
+  ret <2 x i8> %r
+}
+
+define <2 x i8> @test_vector_ssub_add_nsw_no_ov_nonsplat1(<2 x i8> %a, <2 x i8> %b) {
+; CHECK-LABEL: @test_vector_ssub_add_nsw_no_ov_nonsplat1(
+; CHECK-NEXT:    [[AA:%.*]] = add nsw <2 x i8> [[A:%.*]], <i8 7, i8 7>
+; CHECK-NEXT:    [[BB:%.*]] = and <2 x i8> [[B:%.*]], <i8 7, i8 6>
+; CHECK-NEXT:    [[R:%.*]] = call <2 x i8> @llvm.ssub.sat.v2i8(<2 x i8> [[AA]], <2 x i8> [[BB]])
+; CHECK-NEXT:    ret <2 x i8> [[R]]
+;
+  %aa = add nsw <2 x i8> %a, <i8 7, i8 7>
+  %bb = and <2 x i8> %b, <i8 7, i8 6>
+  %r = call <2 x i8> @llvm.ssub.sat.v2i8(<2 x i8> %aa, <2 x i8> %bb)
+  ret <2 x i8> %r
+}
+
+define <2 x i8> @test_vector_ssub_add_nsw_no_ov_nonsplat2(<2 x i8> %a, <2 x i8> %b) {
+; CHECK-LABEL: @test_vector_ssub_add_nsw_no_ov_nonsplat2(
+; CHECK-NEXT:    [[AA:%.*]] = add nsw <2 x i8> [[A:%.*]], <i8 7, i8 8>
+; CHECK-NEXT:    [[BB:%.*]] = and <2 x i8> [[B:%.*]], <i8 7, i8 7>
+; CHECK-NEXT:    [[R:%.*]] = call <2 x i8> @llvm.ssub.sat.v2i8(<2 x i8> [[AA]], <2 x i8> [[BB]])
+; CHECK-NEXT:    ret <2 x i8> [[R]]
+;
+  %aa = add nsw <2 x i8> %a, <i8 7, i8 8>
+  %bb = and <2 x i8> %b, <i8 7, i8 7>
+  %r = call <2 x i8> @llvm.ssub.sat.v2i8(<2 x i8> %aa, <2 x i8> %bb)
+  ret <2 x i8> %r
+}
+
+define <2 x i8> @test_vector_ssub_add_nsw_no_ov_nonsplat3(<2 x i8> %a, <2 x i8> %b) {
+; CHECK-LABEL: @test_vector_ssub_add_nsw_no_ov_nonsplat3(
+; CHECK-NEXT:    [[AA:%.*]] = add nsw <2 x i8> [[A:%.*]], <i8 7, i8 6>
+; CHECK-NEXT:    [[BB:%.*]] = and <2 x i8> [[B:%.*]], <i8 7, i8 6>
+; CHECK-NEXT:    [[R:%.*]] = call <2 x i8> @llvm.ssub.sat.v2i8(<2 x i8> [[AA]], <2 x i8> [[BB]])
+; CHECK-NEXT:    ret <2 x i8> [[R]]
+;
+  %aa = add nsw <2 x i8> %a, <i8 7, i8 6>
+  %bb = and <2 x i8> %b, <i8 7, i8 6>
+  %r = call <2 x i8> @llvm.ssub.sat.v2i8(<2 x i8> %aa, <2 x i8> %bb)
+  ret <2 x i8> %r
+}
+
 ; Raw IR tests
 
 define i32 @uadd_sat(i32 %x, i32 %y) {
-- 
2.7.4