[llvm] r360185 - [InstCombine] Add new combine to add folding
Robert Lougher via llvm-commits
llvm-commits at lists.llvm.org
Tue May 7 12:36:41 PDT 2019
Author: rlougher
Date: Tue May 7 12:36:41 2019
New Revision: 360185
URL: http://llvm.org/viewvc/llvm-project?rev=360185&view=rev
Log:
[InstCombine] Add new combine to add folding
(X | C1) + C2 --> (X | C1) ^ C1 iff (C1 == -C2)
I verified the correctness using Alive:
https://rise4fun.com/Alive/YNV
This transform enables the following transform that already exists in
instcombine:
(X | Y) ^ Y --> X & ~Y
As a result, the full expected transform is:
(X | C1) + C2 --> X & ~C1 iff (C1 == -C2)
There already exists the transform in the sub case:
(X | Y) - Y --> X & ~Y
However this does not trigger in the case where Y is constant due to an earlier
transform:
X - (-C) --> X + C
With this new add fold, both the add and sub constant cases are handled.
Patch by Chris Dawson.
Differential Revision: https://reviews.llvm.org/D61517
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
llvm/trunk/test/Transforms/InstCombine/add.ll
llvm/trunk/test/Transforms/InstCombine/sub.ll
llvm/trunk/test/Transforms/InstCombine/with_overflow.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp?rev=360185&r1=360184&r2=360185&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp Tue May 7 12:36:41 2019
@@ -892,6 +892,11 @@ Instruction *InstCombiner::foldAddWithCo
if (!match(Op1, m_APInt(C)))
return nullptr;
+ // (X | C2) + C --> (X | C2) ^ C2 iff (C2 == -C)
+ const APInt *C2;
+ if (match(Op0, m_Or(m_Value(), m_APInt(C2))) && *C2 == -*C)
+ return BinaryOperator::CreateXor(Op0, ConstantInt::get(Add.getType(), *C2));
+
if (C->isSignMask()) {
// If wrapping is not allowed, then the addition must set the sign bit:
// X + (signmask) --> X | signmask
@@ -906,7 +911,6 @@ Instruction *InstCombiner::foldAddWithCo
// Is this add the last step in a convoluted sext?
// add(zext(xor i16 X, -32768), -32768) --> sext X
Type *Ty = Add.getType();
- const APInt *C2;
if (match(Op0, m_ZExt(m_Xor(m_Value(X), m_APInt(C2)))) &&
C2->isMinSignedValue() && C2->sext(Ty->getScalarSizeInBits()) == *C)
return CastInst::Create(Instruction::SExt, X, Ty);
Modified: llvm/trunk/test/Transforms/InstCombine/add.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/add.ll?rev=360185&r1=360184&r2=360185&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/add.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/add.ll Tue May 7 12:36:41 2019
@@ -982,9 +982,8 @@ define i32 @add_to_sub2(i32 %A, i32 %M)
; (X | C1) + C2 --> (X | C1) ^ C1 iff (C1 == -C2)
define i32 @test44(i32 %A) {
; CHECK-LABEL: @test44(
-; CHECK-NEXT: [[B:%.*]] = or i32 [[A:%.*]], 123
-; CHECK-NEXT: [[C:%.*]] = add nsw i32 [[B]], -123
-; CHECK-NEXT: ret i32 [[C]]
+; CHECK-NEXT: [[TMP1:%.*]] = and i32 [[A:%.*]], -124
+; CHECK-NEXT: ret i32 [[TMP1]]
;
%B = or i32 %A, 123
%C = add i32 %B, -123
@@ -994,8 +993,8 @@ define i32 @test44(i32 %A) {
define i32 @test44_extra_use(i32 %A) {
; CHECK-LABEL: @test44_extra_use(
; CHECK-NEXT: [[B:%.*]] = or i32 [[A:%.*]], 123
-; CHECK-NEXT: [[C:%.*]] = add nsw i32 [[B]], -123
-; CHECK-NEXT: [[D:%.*]] = mul i32 [[B]], [[C]]
+; CHECK-NEXT: [[TMP1:%.*]] = and i32 [[A]], -124
+; CHECK-NEXT: [[D:%.*]] = mul i32 [[B]], [[TMP1]]
; CHECK-NEXT: ret i32 [[D]]
;
%B = or i32 %A, 123
@@ -1017,9 +1016,8 @@ define i32 @test44_non_matching(i32 %A)
define <2 x i32> @test44_vec(<2 x i32> %A) {
; CHECK-LABEL: @test44_vec(
-; CHECK-NEXT: [[B:%.*]] = or <2 x i32> [[A:%.*]], <i32 123, i32 123>
-; CHECK-NEXT: [[C:%.*]] = add nsw <2 x i32> [[B]], <i32 -123, i32 -123>
-; CHECK-NEXT: ret <2 x i32> [[C]]
+; CHECK-NEXT: [[TMP1:%.*]] = and <2 x i32> [[A:%.*]], <i32 -124, i32 -124>
+; CHECK-NEXT: ret <2 x i32> [[TMP1]]
;
%B = or <2 x i32> %A, <i32 123, i32 123>
%C = add <2 x i32> %B, <i32 -123, i32 -123>
Modified: llvm/trunk/test/Transforms/InstCombine/sub.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/sub.ll?rev=360185&r1=360184&r2=360185&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/sub.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/sub.ll Tue May 7 12:36:41 2019
@@ -1270,9 +1270,8 @@ define <2 x i32> @test69(<2 x i32> %x) {
; Check (X | Y) - Y --> X & ~Y when Y is a constant
define i32 @test70(i32 %A) {
; CHECK-LABEL: @test70(
-; CHECK-NEXT: [[B:%.*]] = or i32 [[A:%.*]], 123
-; CHECK-NEXT: [[C:%.*]] = add nsw i32 [[B]], -123
-; CHECK-NEXT: ret i32 [[C]]
+; CHECK-NEXT: [[TMP1:%.*]] = and i32 [[A:%.*]], -124
+; CHECK-NEXT: ret i32 [[TMP1]]
;
%B = or i32 %A, 123
%C = sub i32 %B, 123
Modified: llvm/trunk/test/Transforms/InstCombine/with_overflow.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/with_overflow.ll?rev=360185&r1=360184&r2=360185&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/with_overflow.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/with_overflow.ll Tue May 7 12:36:41 2019
@@ -531,10 +531,9 @@ define { i32, i1 } @umul_canonicalize_co
define { i8, i1 } @uadd_always_overflow(i8 %x) nounwind {
; CHECK-LABEL: @uadd_always_overflow(
-; CHECK-NEXT: [[Y:%.*]] = or i8 [[X:%.*]], -64
-; CHECK-NEXT: [[A:%.*]] = add nsw i8 [[Y]], 64
-; CHECK-NEXT: [[TMP1:%.*]] = insertvalue { i8, i1 } { i8 undef, i1 true }, i8 [[A]], 0
-; CHECK-NEXT: ret { i8, i1 } [[TMP1]]
+; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X:%.*]], 63
+; CHECK-NEXT: [[TMP2:%.*]] = insertvalue { i8, i1 } { i8 undef, i1 true }, i8 [[TMP1]], 0
+; CHECK-NEXT: ret { i8, i1 } [[TMP2]]
;
%y = or i8 %x, 192
%a = call { i8, i1 } @llvm.uadd.with.overflow.i8(i8 %y, i8 64)
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