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[AggressiveInstCombine] Add `{insert/extract}element` to `TruncInstCombine` DAG 

Alive2 for `{insert/extract}element`: https://alive2.llvm.org/ce/z/hwy_E-

Actually, no one file of test suite is touched by this change,
which means that is rare pattern not generated by frontend. But
it's worth being in place.

Differential Revision: https://reviews.llvm.org/D109236
This commit is contained in:
Anton Afanasyev 2021-09-05 17:29:22 +03:00
parent 8371a4c9d5
commit 6a5f49a1ac
2 changed files with 34 additions and 18 deletions
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21
llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp
View File

@ -67,9 +67,13 @@ static void getRelevantOperands(Instruction *I, SmallVectorImpl<Value *> &Ops) {
case Instruction::AShr:
case Instruction::UDiv:
case Instruction::URem:
case Instruction::InsertElement:
Ops.push_back(I->getOperand(0));
Ops.push_back(I->getOperand(1));
break;
case Instruction::ExtractElement:
Ops.push_back(I->getOperand(0));
break;
case Instruction::Select:
Ops.push_back(I->getOperand(1));
Ops.push_back(I->getOperand(2));
@ -138,6 +142,8 @@ bool TruncInstCombine::buildTruncExpressionDag() {
case Instruction::AShr:
case Instruction::UDiv:
case Instruction::URem:
case Instruction::InsertElement:
case Instruction::ExtractElement:
case Instruction::Select: {
SmallVector<Value *, 2> Operands;
getRelevantOperands(I, Operands);
@ -146,7 +152,7 @@ bool TruncInstCombine::buildTruncExpressionDag() {
}
default:
// TODO: Can handle more cases here:
// 1. shufflevector, extractelement, insertelement
// 1. shufflevector
// 2. sdiv, srem
// 3. phi node(and loop handling)
// ...
@ -425,6 +431,19 @@ void TruncInstCombine::ReduceExpressionDag(Type *SclTy) {
ResI->setIsExact(PEO->isExact());
break;
}
case Instruction::ExtractElement: {
Value *Vec = getReducedOperand(I->getOperand(0), SclTy);
Value *Idx = I->getOperand(1);
Res = Builder.CreateExtractElement(Vec, Idx);
break;
}
case Instruction::InsertElement: {
Value *Vec = getReducedOperand(I->getOperand(0), SclTy);
Value *NewElt = getReducedOperand(I->getOperand(1), SclTy);
Value *Idx = I->getOperand(2);
Res = Builder.CreateInsertElement(Vec, NewElt, Idx);
break;
}
case Instruction::Select: {
Value *Op0 = I->getOperand(0);
Value *LHS = getReducedOperand(I->getOperand(1), SclTy);

31
llvm/test/Transforms/AggressiveInstCombine/trunc_vector_instrs.ll
View File

@ -43,12 +43,11 @@ define <4 x i16> @const_shuffle() {
define <2 x i16> @extract_insert(<2 x i8> %a, <2 x i8> %b) {
; CHECK-LABEL: @extract_insert(
; CHECK-NEXT: [[ZEXTA:%.*]] = zext <2 x i8> [[A:%.*]] to <2 x i32>
; CHECK-NEXT: [[ZEXTB:%.*]] = zext <2 x i8> [[B:%.*]] to <2 x i32>
; CHECK-NEXT: [[EXTR:%.*]] = extractelement <2 x i32> [[ZEXTA]], i32 0
; CHECK-NEXT: [[INSR:%.*]] = insertelement <2 x i32> [[ZEXTB]], i32 [[EXTR]], i32 1
; CHECK-NEXT: [[TRUNC:%.*]] = trunc <2 x i32> [[INSR]] to <2 x i16>
; CHECK-NEXT: ret <2 x i16> [[TRUNC]]
; CHECK-NEXT: [[ZEXTA:%.*]] = zext <2 x i8> [[A:%.*]] to <2 x i16>
; CHECK-NEXT: [[ZEXTB:%.*]] = zext <2 x i8> [[B:%.*]] to <2 x i16>
; CHECK-NEXT: [[EXTR:%.*]] = extractelement <2 x i16> [[ZEXTA]], i32 0
; CHECK-NEXT: [[INSR:%.*]] = insertelement <2 x i16> [[ZEXTB]], i16 [[EXTR]], i32 1
; CHECK-NEXT: ret <2 x i16> [[INSR]]
;
%zexta = zext <2 x i8> %a to <2 x i32>
%zextb = zext <2 x i8> %b to <2 x i32>
@ -60,10 +59,9 @@ define <2 x i16> @extract_insert(<2 x i8> %a, <2 x i8> %b) {
define <2 x i16> @insert_poison(i8 %a) {
; CHECK-LABEL: @insert_poison(
; CHECK-NEXT: [[ZEXTA:%.*]] = zext i8 [[A:%.*]] to i32
; CHECK-NEXT: [[INSR:%.*]] = insertelement <2 x i32> poison, i32 [[ZEXTA]], i32 0
; CHECK-NEXT: [[TRUNC:%.*]] = trunc <2 x i32> [[INSR]] to <2 x i16>
; CHECK-NEXT: ret <2 x i16> [[TRUNC]]
; CHECK-NEXT: [[ZEXTA:%.*]] = zext i8 [[A:%.*]] to i16
; CHECK-NEXT: [[INSR:%.*]] = insertelement <2 x i16> poison, i16 [[ZEXTA]], i32 0
; CHECK-NEXT: ret <2 x i16> [[INSR]]
;
%zexta = zext i8 %a to i32
%insr = insertelement <2 x i32> poison, i32 %zexta, i32 0
@ -74,13 +72,12 @@ define <2 x i16> @insert_poison(i8 %a) {
; This demonstrates test not folded by 'opt -instcombine'
define <2 x i16> @extract_mul_insert(<2 x i8> %x) {
; CHECK-LABEL: @extract_mul_insert(
; CHECK-NEXT: [[ZEXT:%.*]] = zext <2 x i8> [[X:%.*]] to <2 x i32>
; CHECK-NEXT: [[LSHR:%.*]] = lshr <2 x i32> [[ZEXT]], <i32 4, i32 5>
; CHECK-NEXT: [[EXTR:%.*]] = extractelement <2 x i32> [[LSHR]], i32 1
; CHECK-NEXT: [[MUL:%.*]] = mul i32 [[EXTR]], 5
; CHECK-NEXT: [[INSR:%.*]] = insertelement <2 x i32> [[LSHR]], i32 [[MUL]], i32 1
; CHECK-NEXT: [[TRUNC:%.*]] = trunc <2 x i32> [[INSR]] to <2 x i16>
; CHECK-NEXT: ret <2 x i16> [[TRUNC]]
; CHECK-NEXT: [[ZEXT:%.*]] = zext <2 x i8> [[X:%.*]] to <2 x i16>
; CHECK-NEXT: [[LSHR:%.*]] = lshr <2 x i16> [[ZEXT]], <i16 4, i16 5>
; CHECK-NEXT: [[EXTR:%.*]] = extractelement <2 x i16> [[LSHR]], i32 1
; CHECK-NEXT: [[MUL:%.*]] = mul i16 [[EXTR]], 5
; CHECK-NEXT: [[INSR:%.*]] = insertelement <2 x i16> [[LSHR]], i16 [[MUL]], i32 1
; CHECK-NEXT: ret <2 x i16> [[INSR]]
;
%zext = zext <2 x i8> %x to <2 x i32>
%lshr = lshr <2 x i32> %zext, <i32 4, i32 5>