[InstCombine] Add tests for folding (icmp eq/ne (and X, -P2), INT_MIN); NFC

Author: goldsteinn

llvm/test/Transforms/InstCombine/icmp-signmask.ll

@@ -0,0 +1,57 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+define i1 @cmp_x_and_negp2_with_eq(i8 %x) {
+; CHECK-LABEL: @cmp_x_and_negp2_with_eq(
+; CHECK-NEXT:    [[ANDX:%.*]] = and i8 [[X:%.*]], -2
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[ANDX]], -128
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %andx = and i8 %x, -2
+  %r = icmp eq i8 %andx, 128
+  ret i1 %r
+}
+
+define i1 @cmp_x_and_negp2_with_eq_fail_not_signmask(i8 %x) {
+; CHECK-LABEL: @cmp_x_and_negp2_with_eq_fail_not_signmask(
+; CHECK-NEXT:    [[ANDX:%.*]] = and i8 [[X:%.*]], -2
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[ANDX]], -124
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %andx = and i8 %x, -2
+  %r = icmp eq i8 %andx, 132
+  ret i1 %r
+}
+
+define <2 x i1> @cmp_x_and_negp2_with_ne(<2 x i8> %x) {
+; CHECK-LABEL: @cmp_x_and_negp2_with_ne(
+; CHECK-NEXT:    [[ANDX:%.*]] = and <2 x i8> [[X:%.*]], <i8 -8, i8 -16>
+; CHECK-NEXT:    [[R:%.*]] = icmp ne <2 x i8> [[ANDX]], <i8 -128, i8 -128>
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %andx = and <2 x i8> %x, <i8 -8, i8 -16>
+  %r = icmp ne <2 x i8> %andx, <i8 128, i8 128>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @cmp_x_and_negp2_with_ne_or_z(<2 x i8> %x) {
+; CHECK-LABEL: @cmp_x_and_negp2_with_ne_or_z(
+; CHECK-NEXT:    [[ANDX:%.*]] = and <2 x i8> [[X:%.*]], <i8 0, i8 -16>
+; CHECK-NEXT:    [[R:%.*]] = icmp ne <2 x i8> [[ANDX]], <i8 -128, i8 -128>
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %andx = and <2 x i8> %x, <i8 0, i8 -16>
+  %r = icmp ne <2 x i8> %andx, <i8 128, i8 128>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @cmp_x_and_negp2_with_ne_fail_not_p2(<2 x i8> %x) {
+; CHECK-LABEL: @cmp_x_and_negp2_with_ne_fail_not_p2(
+; CHECK-NEXT:    [[ANDX:%.*]] = and <2 x i8> [[X:%.*]], <i8 -8, i8 -15>
+; CHECK-NEXT:    [[R:%.*]] = icmp ne <2 x i8> [[ANDX]], <i8 -128, i8 -128>
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %andx = and <2 x i8> %x, <i8 -8, i8 -15>
+  %r = icmp ne <2 x i8> %andx, <i8 128, i8 128>
+  ret <2 x i1> %r
+}