[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

diff --git a/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp b/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp
index 1a6818e..abac3f8 100644 (file)
--- a/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp
+++ b/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp
@@ -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);

diff --git a/llvm/test/Transforms/AggressiveInstCombine/trunc_vector_instrs.ll b/llvm/test/Transforms/AggressiveInstCombine/trunc_vector_instrs.ll
index 2702ab8..975ac13 100644 (file)
--- a/llvm/test/Transforms/AggressiveInstCombine/trunc_vector_instrs.ll
+++ b/llvm/test/Transforms/AggressiveInstCombine/trunc_vector_instrs.ll
@@ -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>