[InstCombine] Add test coverage for Issue llvm#53610

Author: RKSimon

llvm/test/Transforms/InstCombine/negated-bitmask.ll

@@ -0,0 +1,82 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+; PR53610 - sub(0,and(lshr(X,C),1)) --> ashr(shl(X,(BW-1)-C),BW-1)
+
+define i8 @neg_mask1_lshr(i8 %a0) {
+; CHECK-LABEL: @neg_mask1_lshr(
+; CHECK-NEXT:    [[SHIFT:%.*]] = lshr i8 [[A0:%.*]], 3
+; CHECK-NEXT:    [[MASK:%.*]] = and i8 [[SHIFT]], 1
+; CHECK-NEXT:    [[NEG:%.*]] = sub nsw i8 0, [[MASK]]
+; CHECK-NEXT:    ret i8 [[NEG]]
+;
+  %shift = lshr i8 %a0, 3
+  %mask = and i8 %shift, 1
+  %neg = sub i8 0, %mask
+  ret i8 %neg
+}
+
+define <4 x i32> @neg_mask1_lshr_vector_uniform(<4 x i32> %a0) {
+; CHECK-LABEL: @neg_mask1_lshr_vector_uniform(
+; CHECK-NEXT:    [[SHIFT:%.*]] = lshr <4 x i32> [[A0:%.*]], <i32 3, i32 3, i32 3, i32 3>
+; CHECK-NEXT:    [[MASK:%.*]] = and <4 x i32> [[SHIFT]], <i32 1, i32 1, i32 1, i32 1>
+; CHECK-NEXT:    [[NEG:%.*]] = sub nsw <4 x i32> zeroinitializer, [[MASK]]
+; CHECK-NEXT:    ret <4 x i32> [[NEG]]
+;
+  %shift = lshr <4 x i32> %a0, <i32 3, i32 3, i32 3, i32 3>
+  %mask = and <4 x i32> %shift, <i32 1, i32 1, i32 1, i32 1>
+  %neg = sub <4 x i32> zeroinitializer, %mask
+  ret <4 x i32> %neg
+}
+
+define <4 x i32> @neg_mask1_lshr_vector_nonuniform(<4 x i32> %a0) {
+; CHECK-LABEL: @neg_mask1_lshr_vector_nonuniform(
+; CHECK-NEXT:    [[SHIFT:%.*]] = lshr <4 x i32> [[A0:%.*]], <i32 3, i32 4, i32 5, i32 6>
+; CHECK-NEXT:    [[MASK:%.*]] = and <4 x i32> [[SHIFT]], <i32 1, i32 1, i32 1, i32 1>
+; CHECK-NEXT:    [[NEG:%.*]] = sub nsw <4 x i32> zeroinitializer, [[MASK]]
+; CHECK-NEXT:    ret <4 x i32> [[NEG]]
+;
+  %shift = lshr <4 x i32> %a0, <i32 3, i32 4, i32 5, i32 6>
+  %mask = and <4 x i32> %shift, <i32 1, i32 1, i32 1, i32 1>
+  %neg = sub <4 x i32> zeroinitializer, %mask
+  ret <4 x i32> %neg
+}
+
+; Negative Test - wrong mask
+define i8 @neg_mask2_lshr(i8 %a0) {
+; CHECK-LABEL: @neg_mask2_lshr(
+; CHECK-NEXT:    [[SHIFT:%.*]] = lshr i8 [[A0:%.*]], 3
+; CHECK-NEXT:    [[MASK:%.*]] = and i8 [[SHIFT]], 2
+; CHECK-NEXT:    [[NEG:%.*]] = sub nsw i8 0, [[MASK]]
+; CHECK-NEXT:    ret i8 [[NEG]]
+;
+  %shift = lshr i8 %a0, 3
+  %mask = and i8 %shift, 2
+  %neg = sub i8 0, %mask
+  ret i8 %neg
+}
+
+; Negative Test - bad shift amount
+define i8 @neg_mask2_lshr_outofbounds(i8 %a0) {
+; CHECK-LABEL: @neg_mask2_lshr_outofbounds(
+; CHECK-NEXT:    ret i8 poison
+;
+  %shift = lshr i8 %a0, 8
+  %mask = and i8 %shift, 2
+  %neg = sub i8 0, %mask
+  ret i8 %neg
+}
+
+; Negative Test - non-constant shift amount
+define <2 x i32> @neg_mask1_lshr_vector_var(<2 x i32> %a0, <2 x i32> %a1) {
+; CHECK-LABEL: @neg_mask1_lshr_vector_var(
+; CHECK-NEXT:    [[SHIFT:%.*]] = lshr <2 x i32> [[A0:%.*]], [[A1:%.*]]
+; CHECK-NEXT:    [[MASK:%.*]] = and <2 x i32> [[SHIFT]], <i32 1, i32 1>
+; CHECK-NEXT:    [[NEG:%.*]] = sub nsw <2 x i32> zeroinitializer, [[MASK]]
+; CHECK-NEXT:    ret <2 x i32> [[NEG]]
+;
+  %shift = lshr <2 x i32> %a0, %a1
+  %mask = and <2 x i32> %shift, <i32 1, i32 1>
+  %neg = sub <2 x i32> zeroinitializer, %mask
+  ret <2 x i32> %neg
+}