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[InstCombine] Fold Select with binary op - non-commutative opcodes
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Summary:
Basic version was merged - https://reviews.llvm.org/D49954

This adds support for FP & non-commutative opcodes

Precommited tests: https://reviews.llvm.org/rL338727

Reviewers: spatel, lebedev.ri

Reviewed By: spatel

Subscribers: jfb

Differential Revision: https://reviews.llvm.org/D50190

llvm-svn: 339520
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@davidbolvansky
davidbolvansky committed Aug 12, 2018
1 parent dc185ee commit 01d98cc
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Showing 2 changed files with 12 additions and 20 deletions.
5 changes: 3 additions & 2 deletions llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -68,15 +68,16 @@ static Instruction *foldSelectBinOpIdentity(SelectInst &Sel) {

// A select operand must be a binop, and the compare constant must be the
// identity constant for that binop.
// TODO: Support non-commutative binops.
bool IsEq = Pred == ICmpInst::ICMP_EQ;
BinaryOperator *BO;
if (!match(Sel.getOperand(IsEq ? 1 : 2), m_BinOp(BO)) ||
ConstantExpr::getBinOpIdentity(BO->getOpcode(), BO->getType(), false) != C)
ConstantExpr::getBinOpIdentity(BO->getOpcode(), BO->getType(), true) != C)
return nullptr;

// Last, match the compare variable operand with a binop operand.
Value *Y;
if (!BO->isCommutative() && !match(BO, m_BinOp(m_Value(Y), m_Specific(X))))
return nullptr;
if (!match(BO, m_c_BinOp(m_Value(Y), m_Specific(X))))
return nullptr;

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27 changes: 9 additions & 18 deletions llvm/test/Transforms/InstCombine/select-binop-icmp.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -235,8 +235,7 @@ define float @select_fdiv_fcmp(float %x, float %y, float %z) {
define i32 @select_sub_icmp(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @select_sub_icmp(
; CHECK-NEXT: [[A:%.*]] = icmp eq i32 [[X:%.*]], 0
; CHECK-NEXT: [[B:%.*]] = sub i32 [[Z:%.*]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[B]], i32 [[Y:%.*]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Z:%.*]], i32 [[Y:%.*]]
; CHECK-NEXT: ret i32 [[C]]
;
%A = icmp eq i32 %x, 0
Expand All @@ -249,8 +248,7 @@ define i32 @select_sub_icmp_2(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @select_sub_icmp_2(
; CHECK-NEXT: [[A:%.*]] = icmp eq i32 [[X:%.*]], 0
; CHECK-NEXT: call void @use2(i1 [[A]])
; CHECK-NEXT: [[B:%.*]] = sub i32 [[Z:%.*]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[B]], i32 [[Y:%.*]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Z:%.*]], i32 [[Y:%.*]]
; CHECK-NEXT: ret i32 [[C]]
;
%A = icmp eq i32 %x, 0
Expand All @@ -264,8 +262,7 @@ define i32 @select_sub_icmp_3(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @select_sub_icmp_3(
; CHECK-NEXT: [[A:%.*]] = icmp ne i32 [[X:%.*]], 0
; CHECK-NEXT: call void @use2(i1 [[A]])
; CHECK-NEXT: [[B:%.*]] = sub i32 [[Z:%.*]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Y:%.*]], i32 [[B]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Y:%.*]], i32 [[Z:%.*]]
; CHECK-NEXT: ret i32 [[C]]
;
%A = icmp ne i32 %x, 0
Expand All @@ -278,8 +275,7 @@ define i32 @select_sub_icmp_3(i32 %x, i32 %y, i32 %z) {
define <2 x i8> @select_sub_icmp_vec(<2 x i8> %x, <2 x i8> %y, <2 x i8> %z) {
; CHECK-LABEL: @select_sub_icmp_vec(
; CHECK-NEXT: [[A:%.*]] = icmp eq <2 x i8> [[X:%.*]], zeroinitializer
; CHECK-NEXT: [[B:%.*]] = sub <2 x i8> [[Z:%.*]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select <2 x i1> [[A]], <2 x i8> [[B]], <2 x i8> [[Y:%.*]]
; CHECK-NEXT: [[C:%.*]] = select <2 x i1> [[A]], <2 x i8> [[Z:%.*]], <2 x i8> [[Y:%.*]]
; CHECK-NEXT: ret <2 x i8> [[C]]
;
%A = icmp eq <2 x i8> %x, <i8 0, i8 0>
Expand All @@ -292,8 +288,7 @@ define i32 @select_shl_icmp(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @select_shl_icmp(
; CHECK-NEXT: [[A:%.*]] = icmp ne i32 [[X:%.*]], 0
; CHECK-NEXT: call void @use2(i1 [[A]])
; CHECK-NEXT: [[B:%.*]] = shl i32 [[Z:%.*]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Y:%.*]], i32 [[B]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Y:%.*]], i32 [[Z:%.*]]
; CHECK-NEXT: ret i32 [[C]]
;
%A = icmp ne i32 %x, 0
Expand All @@ -306,8 +301,7 @@ define i32 @select_shl_icmp(i32 %x, i32 %y, i32 %z) {
define i32 @select_lshr_icmp(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @select_lshr_icmp(
; CHECK-NEXT: [[A:%.*]] = icmp eq i32 [[X:%.*]], 0
; CHECK-NEXT: [[B:%.*]] = lshr i32 [[Z:%.*]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[B]], i32 [[Y:%.*]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Z:%.*]], i32 [[Y:%.*]]
; CHECK-NEXT: ret i32 [[C]]
;
%A = icmp eq i32 %x, 0
Expand All @@ -320,8 +314,7 @@ define i32 @select_ashr_icmp(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @select_ashr_icmp(
; CHECK-NEXT: [[A:%.*]] = icmp ne i32 [[X:%.*]], 0
; CHECK-NEXT: call void @use2(i1 [[A]])
; CHECK-NEXT: [[B:%.*]] = ashr i32 [[Z:%.*]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Y:%.*]], i32 [[B]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Y:%.*]], i32 [[Z:%.*]]
; CHECK-NEXT: ret i32 [[C]]
;
%A = icmp ne i32 %x, 0
Expand All @@ -334,8 +327,7 @@ define i32 @select_ashr_icmp(i32 %x, i32 %y, i32 %z) {
define i32 @select_udiv_icmp(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @select_udiv_icmp(
; CHECK-NEXT: [[A:%.*]] = icmp eq i32 [[X:%.*]], 1
; CHECK-NEXT: [[B:%.*]] = udiv i32 [[Z:%.*]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[B]], i32 [[Y:%.*]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Z:%.*]], i32 [[Y:%.*]]
; CHECK-NEXT: ret i32 [[C]]
;
%A = icmp eq i32 %x, 1
Expand All @@ -348,8 +340,7 @@ define i32 @select_sdiv_icmp(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @select_sdiv_icmp(
; CHECK-NEXT: [[A:%.*]] = icmp ne i32 [[X:%.*]], 1
; CHECK-NEXT: call void @use2(i1 [[A]])
; CHECK-NEXT: [[B:%.*]] = sdiv i32 [[Z:%.*]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Y:%.*]], i32 [[B]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Y:%.*]], i32 [[Z:%.*]]
; CHECK-NEXT: ret i32 [[C]]
;
%A = icmp ne i32 %x, 1
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