[llvm] r364739 - [NFC][InstCombine] Tests for x - ~(y) -> x + y + 1 fold (PR42457)

[Roman Lebedev via llvm-commits]

Author: lebedevri
Date: Mon Jul  1 02:57:53 2019
New Revision: 364739

URL: http://llvm.org/viewvc/llvm-project?rev=364739&view=rev
Log:
[NFC][InstCombine] Tests for x - ~(y)  ->  x + y + 1 fold (PR42457)

https://bugs.llvm.org/show_bug.cgi?id=42457
https://rise4fun.com/Alive/iFhE

Added:
    llvm/trunk/test/Transforms/InstCombine/fold-sub-of-not-to-inc-of-add.ll

Added: llvm/trunk/test/Transforms/InstCombine/fold-sub-of-not-to-inc-of-add.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/fold-sub-of-not-to-inc-of-add.ll?rev=364739&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/fold-sub-of-not-to-inc-of-add.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/fold-sub-of-not-to-inc-of-add.ll Mon Jul  1 02:57:53 2019
@@ -0,0 +1,94 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -instcombine -S < %s | FileCheck %s
+
+; Given:
+;   sub %y, (xor %x, -1)
+; Transform it to:
+;   add (add %x, %y), 1
+
+;------------------------------------------------------------------------------;
+; Scalar tests
+;------------------------------------------------------------------------------;
+
+define i32 @p0_scalar(i32 %x, i32 %y) {
+; CHECK-LABEL: @p0_scalar(
+; CHECK-NEXT:    [[T0:%.*]] = xor i32 [[X:%.*]], -1
+; CHECK-NEXT:    [[T1:%.*]] = sub i32 [[Y:%.*]], [[T0]]
+; CHECK-NEXT:    ret i32 [[T1]]
+;
+  %t0 = xor i32 %x, -1
+  %t1 = sub i32 %y, %t0
+  ret i32 %t1
+}
+
+;------------------------------------------------------------------------------;
+; Vector tests
+;------------------------------------------------------------------------------;
+
+define <4 x i32> @p1_vector_splat(<4 x i32> %x, <4 x i32> %y) {
+; CHECK-LABEL: @p1_vector_splat(
+; CHECK-NEXT:    [[T0:%.*]] = xor <4 x i32> [[X:%.*]], <i32 -1, i32 -1, i32 -1, i32 -1>
+; CHECK-NEXT:    [[T1:%.*]] = sub <4 x i32> [[Y:%.*]], [[T0]]
+; CHECK-NEXT:    ret <4 x i32> [[T1]]
+;
+  %t0 = xor <4 x i32> %x, <i32 -1, i32 -1, i32 -1, i32 -1>
+  %t1 = sub <4 x i32> %y, %t0
+  ret <4 x i32> %t1
+}
+
+define <4 x i32> @p2_vector_undef(<4 x i32> %x, <4 x i32> %y) {
+; CHECK-LABEL: @p2_vector_undef(
+; CHECK-NEXT:    [[T0:%.*]] = xor <4 x i32> [[X:%.*]], <i32 -1, i32 -1, i32 undef, i32 -1>
+; CHECK-NEXT:    [[T1:%.*]] = sub <4 x i32> [[Y:%.*]], [[T0]]
+; CHECK-NEXT:    ret <4 x i32> [[T1]]
+;
+  %t0 = xor <4 x i32> %x, <i32 -1, i32 -1, i32 undef, i32 -1>
+  %t1 = sub <4 x i32> %y, %t0
+  ret <4 x i32> %t1
+}
+
+;------------------------------------------------------------------------------;
+; One-use test
+;------------------------------------------------------------------------------;
+
+declare void @use32(i32)
+
+define i32 @p3_oneuse(i32 %x, i32 %y) {
+; CHECK-LABEL: @p3_oneuse(
+; CHECK-NEXT:    [[T0:%.*]] = xor i32 [[X:%.*]], -1
+; CHECK-NEXT:    call void @use32(i32 [[T0]])
+; CHECK-NEXT:    [[T1:%.*]] = sub i32 [[Y:%.*]], [[T0]]
+; CHECK-NEXT:    ret i32 [[T1]]
+;
+  %t0 = xor i32 %x, -1
+  call void @use32(i32 %t0)
+  %t1 = sub i32 %y, %t0
+  ret i32 %t1
+}
+
+;------------------------------------------------------------------------------;
+; Basic negative tests
+;------------------------------------------------------------------------------;
+
+; The `sub` (and the fold) is not commutative.
+define i32 @n4(i32 %x, i32 %y) {
+; CHECK-LABEL: @n4(
+; CHECK-NEXT:    [[T0:%.*]] = xor i32 [[X:%.*]], -1
+; CHECK-NEXT:    [[T1:%.*]] = sub i32 [[T0]], [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[T1]]
+;
+  %t0 = xor i32 %x, -1
+  %t1 = sub i32 %t0, %y ; swapped
+  ret i32 %t1
+}
+
+define i32 @n5_is_not_not(i32 %x, i32 %y) {
+; CHECK-LABEL: @n5_is_not_not(
+; CHECK-NEXT:    [[T0:%.*]] = xor i32 [[X:%.*]], 2147483647
+; CHECK-NEXT:    [[T1:%.*]] = sub i32 [[Y:%.*]], [[T0]]
+; CHECK-NEXT:    ret i32 [[T1]]
+;
+  %t0 = xor i32 %x, 2147483647 ; not -1
+  %t1 = sub i32 %y, %t0
+  ret i32 %t1
+}