[llvm] Simplify `(a % b) lt/ge (b-1)` into `(a % b) eq/ne (b-1)` (PR #72504)
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Mon Jan 15 09:49:28 PST 2024
================
@@ -10,6 +10,307 @@ declare void @use_i8(i8)
declare void @use_i32(i32)
declare void @use_i64(i64)
+; tests for (x % c) >=/ < (c - 1), where c >= 0
+define i1 @srem_sgt_test1(i64 %x) {
+; CHECK-LABEL: @srem_sgt_test1(
+; CHECK-NEXT: [[Y:%.*]] = srem i64 [[X:%.*]], 34360750831
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[Y]], 34360750830
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %y = srem i64 %x, 34360750831
+ %cmp = icmp sgt i64 %y, 34360750829
+ ret i1 %cmp
+}
+
+define i1 @srem_slt_test1(i64 %x) {
+; CHECK-LABEL: @srem_slt_test1(
+; CHECK-NEXT: [[Y:%.*]] = srem i64 [[X:%.*]], 34360750831
+; CHECK-NEXT: [[CMP:%.*]] = icmp ne i64 [[Y]], 34360750830
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %y = srem i64 %x, 34360750831
+ %cmp = icmp slt i64 %y, 34360750830
+ ret i1 %cmp
+}
+
+define i1 @srem_sgt_test2(i32 %x) {
+; CHECK-LABEL: @srem_sgt_test2(
+; CHECK-NEXT: [[Y:%.*]] = srem i32 [[X:%.*]], 1074977277
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[Y]], 1074977276
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %y = srem i32 %x, 1074977277
+ %cmp = icmp sgt i32 %y, 1074977275
+ ret i1 %cmp
+}
+
+define i1 @srem_slt_test2(i32 %x) {
+; CHECK-LABEL: @srem_slt_test2(
+; CHECK-NEXT: [[Y:%.*]] = srem i32 [[X:%.*]], 1074977277
+; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[Y]], 1074977276
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %y = srem i32 %x, 1074977277
+ %cmp = icmp slt i32 %y, 1074977276
+ ret i1 %cmp
+}
+
+define i1 @srem_sgt_test3(i16 %x) {
+; CHECK-LABEL: @srem_sgt_test3(
+; CHECK-NEXT: [[Y:%.*]] = srem i16 [[X:%.*]], 2259
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i16 [[Y]], 2258
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %y = srem i16 %x, 2259
+ %cmp = icmp sgt i16 %y, 2257
+ ret i1 %cmp
+}
+
+define i1 @srem_slt_test3(i16 %x) {
+; CHECK-LABEL: @srem_slt_test3(
+; CHECK-NEXT: [[Y:%.*]] = srem i16 [[X:%.*]], 2259
+; CHECK-NEXT: [[CMP:%.*]] = icmp ne i16 [[Y]], 2258
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %y = srem i16 %x, 2259
+ %cmp = icmp slt i16 %y, 2258
+ ret i1 %cmp
+}
+
+define i1 @srem_sgt_test4(i8 %x) {
+; CHECK-LABEL: @srem_sgt_test4(
+; CHECK-NEXT: ret i1 true
+;
+ %y = srem i8 %x, 133
+ %cmp = icmp sgt i8 %y, 131
+ ret i1 %cmp
+}
+
+define i1 @srem_slt_test4(i8 %x) {
+; CHECK-LABEL: @srem_slt_test4(
+; CHECK-NEXT: ret i1 false
+;
+ %y = srem i8 %x, 133
+ %cmp = icmp slt i8 %y, 132
+ ret i1 %cmp
+}
+
+define i1 @test_srem_slt_constant(i32 %a) {
+; CHECK-LABEL: @test_srem_slt_constant(
+; CHECK-NEXT: [[TMP1:%.*]] = and i32 [[A:%.*]], -2147483137
+; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[TMP1]], 511
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %y = srem i32 %a, 512
+ %cmp = icmp slt i32 %y, 511
+ ret i1 %cmp
+}
+
+define i1 @test_srem_sgt_constant(i32 %a) {
+; CHECK-LABEL: @test_srem_sgt_constant(
+; CHECK-NEXT: [[TMP1:%.*]] = and i32 [[A:%.*]], -2147483137
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP1]], 511
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %y = srem i32 %a, 512
+ %cmp = icmp sgt i32 %y, 510
+ ret i1 %cmp
+}
+
+define <2 x i1> @test_srem_slt_constant_splat(<2 x i32> %a) {
+; CHECK-LABEL: @test_srem_slt_constant_splat(
+; CHECK-NEXT: [[TMP1:%.*]] = and <2 x i32> [[A:%.*]], <i32 -2147483137, i32 -2147483137>
+; CHECK-NEXT: [[CMP:%.*]] = icmp ne <2 x i32> [[TMP1]], <i32 511, i32 511>
+; CHECK-NEXT: ret <2 x i1> [[CMP]]
+;
+ %y = srem <2 x i32> %a, <i32 512, i32 512>
+ %cmp = icmp slt <2 x i32> %y, <i32 511, i32 511>
+ ret <2 x i1> %cmp
+}
+
+define <2 x i1> @test_srem_sgt_constant_splat(<2 x i32> %a) {
+; CHECK-LABEL: @test_srem_sgt_constant_splat(
+; CHECK-NEXT: [[TMP1:%.*]] = and <2 x i32> [[A:%.*]], <i32 -2147483137, i32 -2147483137>
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq <2 x i32> [[TMP1]], <i32 511, i32 511>
+; CHECK-NEXT: ret <2 x i1> [[CMP]]
+;
+ %y = srem <2 x i32> %a, <i32 512, i32 512>
+ %cmp = icmp sgt <2 x i32> %y, <i32 510, i32 510>
+ ret <2 x i1> %cmp
+}
+
+; tests for (x % c) <=/> (c + 1), where y < 0
+define i1 @srem_sgt_test(i16 %x) {
+; CHECK-LABEL: @srem_sgt_test(
+; CHECK-NEXT: [[Y:%.*]] = srem i16 [[X:%.*]], 2259
+; CHECK-NEXT: [[CMP:%.*]] = icmp ne i16 [[Y]], -2258
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %y = srem i16 %x, -2259
+ %cmp = icmp sgt i16 %y, -2258
+ ret i1 %cmp
+}
+
+define i1 @srem_sle_test(i16 %x) {
+; CHECK-LABEL: @srem_sle_test(
+; CHECK-NEXT: [[Y:%.*]] = srem i16 [[X:%.*]], 2259
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i16 [[Y]], -2258
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %y = srem i16 %x, -2259
+ %cmp = icmp slt i16 %y, -2257
+ ret i1 %cmp
+}
+
+define <2 x i1> @test_srem_sgt_constant_splat_neg(<2 x i32> %a) {
+; CHECK-LABEL: @test_srem_sgt_constant_splat_neg(
+; CHECK-NEXT: [[Y:%.*]] = srem <2 x i32> [[A:%.*]], <i32 512, i32 512>
+; CHECK-NEXT: [[CMP:%.*]] = icmp ne <2 x i32> [[Y]], <i32 -511, i32 -511>
+; CHECK-NEXT: ret <2 x i1> [[CMP]]
+;
+ %y = srem <2 x i32> %a, <i32 -512, i32 -512>
+ %cmp = icmp sgt <2 x i32> %y, <i32 -511, i32 -511>
+ ret <2 x i1> %cmp
+}
+
+define <2 x i1> @test_srem_slt_constant_splat_neg(<2 x i32> %a) {
+; CHECK-LABEL: @test_srem_slt_constant_splat_neg(
+; CHECK-NEXT: [[Y:%.*]] = srem <2 x i32> [[A:%.*]], <i32 512, i32 512>
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq <2 x i32> [[Y]], <i32 -511, i32 -511>
+; CHECK-NEXT: ret <2 x i1> [[CMP]]
+;
+ %y = srem <2 x i32> %a, <i32 -512, i32 -512>
+ %cmp = icmp slt <2 x i32> %y, <i32 -510, i32 -510>
+ ret <2 x i1> %cmp
+}
+
+; tests for handling urem w/ slt/sge/uge/ult
+define i1 @test_urem_slt(i32 %x) {
+; CHECK-LABEL: @test_urem_slt(
+; CHECK-NEXT: [[Y:%.*]] = urem i32 [[X:%.*]], 12235
+; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[Y]], 12234
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %y = urem i32 %x, 12235
+ %cmp = icmp slt i32 %y, 12234
+ ret i1 %cmp
+}
+
+define i1 @test_urem_sge(i32 %x) {
+; CHECK-LABEL: @test_urem_sge(
+; CHECK-NEXT: [[Y:%.*]] = urem i32 [[X:%.*]], 13546
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[Y]], 13545
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %y = urem i32 %x, 13546
+ %cmp = icmp sge i32 %y, 13545
+ ret i1 %cmp
+}
+
+define i1 @test_urem_uge(i32 %x) {
+; CHECK-LABEL: @test_urem_uge(
+; CHECK-NEXT: [[Y:%.*]] = urem i32 [[X:%.*]], 18642
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[Y]], 18641
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %y = urem i32 %x, 18642
+ %cmp = icmp ugt i32 %y, 18640
+ ret i1 %cmp
+}
+
+define i1 @test_urem_ult(i32 %x) {
+; CHECK-LABEL: @test_urem_ult(
+; CHECK-NEXT: [[Y:%.*]] = urem i32 [[X:%.*]], 15344
+; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[Y]], 15343
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %y = urem i32 %x, 15344
+ %cmp = icmp ult i32 %y, 15343
+ ret i1 %cmp
+}
----------------
nikic wrote:
I'd like to see some negative tests with off by one constants. For example here `ult 15342` should not transform.
https://github.com/llvm/llvm-project/pull/72504
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