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[InstCombine] Fold icmp eq/ne (and %x, C), 0 iff (-C) is power of two…
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… -> %x u</u>= (-C) earlier.

Summary:
To generate simplified IR, make sure fold
  (X & ~C) ==/!= 0 --> X u</u>= C+1

is scheduled before fold
  ((X << Y) & C) == 0 -> (X & (C >> Y)) == 0.

https://rise4fun.com/Alive/7ZN

Reviewers: lebedev.ri, efriedma, spatel, craig.topper

Reviewed By: lebedev.ri

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63505

llvm-svn: 364255
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@huihzhang
huihzhang committed Jun 25, 2019
1 parent 545f001 commit 4626613
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Showing 4 changed files with 37 additions and 51 deletions.
20 changes: 9 additions & 11 deletions llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
View file
Expand Up @@ -1652,6 +1652,15 @@ Instruction *InstCombiner::foldICmpAndConstConst(ICmpInst &Cmp,
auto NewPred = isICMP_NE ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
return new ICmpInst(NewPred, X, Zero);
}

// Restrict this fold only for single-use 'and' (PR10267).
// ((%x & C) == 0) --> %x u< (-C) iff (-C) is power of two.
if ((~(*C2) + 1).isPowerOf2()) {
Constant *NegBOC =
ConstantExpr::getNeg(cast<Constant>(And->getOperand(1)));
auto NewPred = isICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
return new ICmpInst(NewPred, X, NegBOC);
}
}

// If the LHS is an 'and' of a truncate and we can widen the and/compare to
Expand Down Expand Up @@ -2797,17 +2806,6 @@ Instruction *InstCombiner::foldICmpBinOpEqualityWithConstant(ICmpInst &Cmp,
if (C == *BOC && C.isPowerOf2())
return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE,
BO, Constant::getNullValue(RHS->getType()));

// Don't perform the following transforms if the AND has multiple uses
if (!BO->hasOneUse())
break;

// ((X & ~7) == 0) --> X < 8
if (C.isNullValue() && (~(*BOC) + 1).isPowerOf2()) {
Constant *NegBOC = ConstantExpr::getNeg(cast<Constant>(BOp1));
auto NewPred = isICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
return new ICmpInst(NewPred, BOp0, NegBOC);
}
}
break;
}
Expand Down
30 changes: 12 additions & 18 deletions llvm/test/Transforms/InstCombine/lshr-and-negC-icmpeq-zero.ll
View file
Expand Up @@ -9,9 +9,8 @@

define i1 @scalar_i8_lshr_and_negC_eq(i8 %x, i8 %y) {
; CHECK-LABEL: @scalar_i8_lshr_and_negC_eq(
; CHECK-NEXT: [[TMP1:%.*]] = shl i8 -4, [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = and i8 [[TMP1]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[TMP2]], 0
; CHECK-NEXT: [[LSHR:%.*]] = lshr i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ult i8 [[LSHR]], 4
; CHECK-NEXT: ret i1 [[R]]
;
%lshr = lshr i8 %x, %y
Expand All @@ -22,9 +21,8 @@ define i1 @scalar_i8_lshr_and_negC_eq(i8 %x, i8 %y) {

define i1 @scalar_i16_lshr_and_negC_eq(i16 %x, i16 %y) {
; CHECK-LABEL: @scalar_i16_lshr_and_negC_eq(
; CHECK-NEXT: [[TMP1:%.*]] = shl i16 -128, [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = and i16 [[TMP1]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i16 [[TMP2]], 0
; CHECK-NEXT: [[LSHR:%.*]] = lshr i16 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ult i16 [[LSHR]], 128
; CHECK-NEXT: ret i1 [[R]]
;
%lshr = lshr i16 %x, %y
Expand All @@ -35,9 +33,8 @@ define i1 @scalar_i16_lshr_and_negC_eq(i16 %x, i16 %y) {

define i1 @scalar_i32_lshr_and_negC_eq(i32 %x, i32 %y) {
; CHECK-LABEL: @scalar_i32_lshr_and_negC_eq(
; CHECK-NEXT: [[TMP1:%.*]] = shl i32 -262144, [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = and i32 [[TMP1]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i32 [[TMP2]], 0
; CHECK-NEXT: [[LSHR:%.*]] = lshr i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ult i32 [[LSHR]], 262144
; CHECK-NEXT: ret i1 [[R]]
;
%lshr = lshr i32 %x, %y
Expand All @@ -48,9 +45,8 @@ define i1 @scalar_i32_lshr_and_negC_eq(i32 %x, i32 %y) {

define i1 @scalar_i64_lshr_and_negC_eq(i64 %x, i64 %y) {
; CHECK-LABEL: @scalar_i64_lshr_and_negC_eq(
; CHECK-NEXT: [[TMP1:%.*]] = shl i64 -8589934592, [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = and i64 [[TMP1]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i64 [[TMP2]], 0
; CHECK-NEXT: [[LSHR:%.*]] = lshr i64 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ult i64 [[LSHR]], 8589934592
; CHECK-NEXT: ret i1 [[R]]
;
%lshr = lshr i64 %x, %y
Expand All @@ -61,9 +57,8 @@ define i1 @scalar_i64_lshr_and_negC_eq(i64 %x, i64 %y) {

define i1 @scalar_i32_lshr_and_negC_ne(i32 %x, i32 %y) {
; CHECK-LABEL: @scalar_i32_lshr_and_negC_ne(
; CHECK-NEXT: [[TMP1:%.*]] = shl i32 -262144, [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = and i32 [[TMP1]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ne i32 [[TMP2]], 0
; CHECK-NEXT: [[LSHR:%.*]] = lshr i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ugt i32 [[LSHR]], 262143
; CHECK-NEXT: ret i1 [[R]]
;
%lshr = lshr i32 %x, %y
Expand All @@ -76,9 +71,8 @@ define i1 @scalar_i32_lshr_and_negC_ne(i32 %x, i32 %y) {

define <4 x i1> @vec_4xi32_lshr_and_negC_eq(<4 x i32> %x, <4 x i32> %y) {
; CHECK-LABEL: @vec_4xi32_lshr_and_negC_eq(
; CHECK-NEXT: [[TMP1:%.*]] = shl <4 x i32> <i32 -8, i32 -8, i32 -8, i32 -8>, [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = and <4 x i32> [[TMP1]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp eq <4 x i32> [[TMP2]], zeroinitializer
; CHECK-NEXT: [[LSHR:%.*]] = lshr <4 x i32> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ult <4 x i32> [[LSHR]], <i32 8, i32 8, i32 8, i32 8>
; CHECK-NEXT: ret <4 x i1> [[R]]
;
%lshr = lshr <4 x i32> %x, %y
Expand Down
8 changes: 4 additions & 4 deletions llvm/test/Transforms/InstCombine/pr17827.ll
View file
Expand Up @@ -66,8 +66,8 @@ define <2 x i1> @test_shift_and_cmp_changed1_vec(<2 x i8> %p, <2 x i8> %q) {
; Unsigned compare allows a transformation to compare against 0.
define i1 @test_shift_and_cmp_changed2(i8 %p) {
; CHECK-LABEL: @test_shift_and_cmp_changed2(
; CHECK-NEXT: [[ANDP:%.*]] = and i8 [[P:%.*]], 6
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[ANDP]], 0
; CHECK-NEXT: [[SHLP:%.*]] = shl i8 [[P:%.*]], 5
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i8 [[SHLP]], 64
; CHECK-NEXT: ret i1 [[CMP]]
;
%shlp = shl i8 %p, 5
Expand All @@ -78,8 +78,8 @@ define i1 @test_shift_and_cmp_changed2(i8 %p) {

define <2 x i1> @test_shift_and_cmp_changed2_vec(<2 x i8> %p) {
; CHECK-LABEL: @test_shift_and_cmp_changed2_vec(
; CHECK-NEXT: [[ANDP:%.*]] = and <2 x i8> [[P:%.*]], <i8 6, i8 6>
; CHECK-NEXT: [[CMP:%.*]] = icmp eq <2 x i8> [[ANDP]], zeroinitializer
; CHECK-NEXT: [[SHLP:%.*]] = shl <2 x i8> [[P:%.*]], <i8 5, i8 5>
; CHECK-NEXT: [[CMP:%.*]] = icmp ult <2 x i8> [[SHLP]], <i8 64, i8 64>
; CHECK-NEXT: ret <2 x i1> [[CMP]]
;
%shlp = shl <2 x i8> %p, <i8 5, i8 5>
Expand Down
30 changes: 12 additions & 18 deletions llvm/test/Transforms/InstCombine/shl-and-negC-icmpeq-zero.ll
View file
Expand Up @@ -9,9 +9,8 @@

define i1 @scalar_i8_shl_and_negC_eq(i8 %x, i8 %y) {
; CHECK-LABEL: @scalar_i8_shl_and_negC_eq(
; CHECK-NEXT: [[TMP1:%.*]] = lshr i8 -4, [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = and i8 [[TMP1]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[TMP2]], 0
; CHECK-NEXT: [[SHL:%.*]] = shl i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ult i8 [[SHL]], 4
; CHECK-NEXT: ret i1 [[R]]
;
%shl = shl i8 %x, %y
Expand All @@ -22,9 +21,8 @@ define i1 @scalar_i8_shl_and_negC_eq(i8 %x, i8 %y) {

define i1 @scalar_i16_shl_and_negC_eq(i16 %x, i16 %y) {
; CHECK-LABEL: @scalar_i16_shl_and_negC_eq(
; CHECK-NEXT: [[TMP1:%.*]] = lshr i16 -128, [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = and i16 [[TMP1]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i16 [[TMP2]], 0
; CHECK-NEXT: [[SHL:%.*]] = shl i16 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ult i16 [[SHL]], 128
; CHECK-NEXT: ret i1 [[R]]
;
%shl = shl i16 %x, %y
Expand All @@ -35,9 +33,8 @@ define i1 @scalar_i16_shl_and_negC_eq(i16 %x, i16 %y) {

define i1 @scalar_i32_shl_and_negC_eq(i32 %x, i32 %y) {
; CHECK-LABEL: @scalar_i32_shl_and_negC_eq(
; CHECK-NEXT: [[TMP1:%.*]] = lshr i32 -262144, [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = and i32 [[TMP1]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i32 [[TMP2]], 0
; CHECK-NEXT: [[SHL:%.*]] = shl i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ult i32 [[SHL]], 262144
; CHECK-NEXT: ret i1 [[R]]
;
%shl = shl i32 %x, %y
Expand All @@ -48,9 +45,8 @@ define i1 @scalar_i32_shl_and_negC_eq(i32 %x, i32 %y) {

define i1 @scalar_i64_shl_and_negC_eq(i64 %x, i64 %y) {
; CHECK-LABEL: @scalar_i64_shl_and_negC_eq(
; CHECK-NEXT: [[TMP1:%.*]] = lshr i64 -8589934592, [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = and i64 [[TMP1]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i64 [[TMP2]], 0
; CHECK-NEXT: [[SHL:%.*]] = shl i64 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ult i64 [[SHL]], 8589934592
; CHECK-NEXT: ret i1 [[R]]
;
%shl = shl i64 %x, %y
Expand All @@ -61,9 +57,8 @@ define i1 @scalar_i64_shl_and_negC_eq(i64 %x, i64 %y) {

define i1 @scalar_i32_shl_and_negC_ne(i32 %x, i32 %y) {
; CHECK-LABEL: @scalar_i32_shl_and_negC_ne(
; CHECK-NEXT: [[TMP1:%.*]] = lshr i32 -262144, [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = and i32 [[TMP1]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ne i32 [[TMP2]], 0
; CHECK-NEXT: [[SHL:%.*]] = shl i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ugt i32 [[SHL]], 262143
; CHECK-NEXT: ret i1 [[R]]
;
%shl = shl i32 %x, %y
Expand All @@ -76,9 +71,8 @@ define i1 @scalar_i32_shl_and_negC_ne(i32 %x, i32 %y) {

define <4 x i1> @vec_4xi32_shl_and_negC_eq(<4 x i32> %x, <4 x i32> %y) {
; CHECK-LABEL: @vec_4xi32_shl_and_negC_eq(
; CHECK-NEXT: [[TMP1:%.*]] = lshr <4 x i32> <i32 -8, i32 -8, i32 -8, i32 -8>, [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = and <4 x i32> [[TMP1]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp eq <4 x i32> [[TMP2]], zeroinitializer
; CHECK-NEXT: [[SHL:%.*]] = shl <4 x i32> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ult <4 x i32> [[SHL]], <i32 8, i32 8, i32 8, i32 8>
; CHECK-NEXT: ret <4 x i1> [[R]]
;
%shl = shl <4 x i32> %x, %y
Expand Down

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