From 4f878fe3a7d5f62b726e83bde0a23a268a875734 Mon Sep 17 00:00:00 2001
From: Roman Lebedev <lebedev.ri@gmail.com>
Date: Mon, 1 Jul 2019 09:57:53 +0000
Subject: [PATCH] [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

llvm-svn: 364739
---
 .../fold-sub-of-not-to-inc-of-add.ll          | 94 +++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 llvm/test/Transforms/InstCombine/fold-sub-of-not-to-inc-of-add.ll

diff --git a/llvm/test/Transforms/InstCombine/fold-sub-of-not-to-inc-of-add.ll b/llvm/test/Transforms/InstCombine/fold-sub-of-not-to-inc-of-add.ll
new file mode 100644
index 000000000000..1febe4bafab8
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/fold-sub-of-not-to-inc-of-add.ll
@@ -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
+}
-- 
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