[llvm] 90668d2 - [CVP][LVI] Add support for InsertElementInst in LVI (#99368)

[via llvm-commits]

Author: Rajat Bajpai
Date: 2024-07-19T08:46:41+02:00
New Revision: 90668d240417422827d0468aa32b6aaa88105859

URL: https://github.com/llvm/llvm-project/commit/90668d240417422827d0468aa32b6aaa88105859
DIFF: https://github.com/llvm/llvm-project/commit/90668d240417422827d0468aa32b6aaa88105859.diff

LOG: [CVP][LVI] Add support for InsertElementInst in LVI (#99368)

Currently, the LVI analysis pass doesn't support InsertElementInst
vector instruction. Due to this, some optimization opportunities are
missed. For example, in the below example, ICMP instruction can be
folded but it doesn't.

```
...
%ie1 = insertelement <2 x i32> poison, i32 10, i64 0
%ie2 = insertelement <2 x i32> %ie1, i32 20, i64 1
%icmp = icmp <2 x i1> %ie2, <i32 40, i32 40>
...
```

This change adds InsertElementInst support in the LVI analysis pass to
fix the motivating example.

Added: 
    

Modified: 
    llvm/lib/Analysis/LazyValueInfo.cpp
    llvm/test/Transforms/CorrelatedValuePropagation/vectors.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index 92389f2896b8e..4c023ed5ed8f0 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -428,6 +428,8 @@ class LazyValueInfoImpl {
   std::optional<ValueLatticeElement> solveBlockValueIntrinsic(IntrinsicInst *II,
                                                               BasicBlock *BB);
   std::optional<ValueLatticeElement>
+  solveBlockValueInsertElement(InsertElementInst *IEI, BasicBlock *BB);
+  std::optional<ValueLatticeElement>
   solveBlockValueExtractValue(ExtractValueInst *EVI, BasicBlock *BB);
   bool isNonNullAtEndOfBlock(Value *Val, BasicBlock *BB);
   void intersectAssumeOrGuardBlockValueConstantRange(Value *Val,
@@ -657,6 +659,9 @@ LazyValueInfoImpl::solveBlockValueImpl(Value *Val, BasicBlock *BB) {
     if (BinaryOperator *BO = dyn_cast<BinaryOperator>(BBI))
       return solveBlockValueBinaryOp(BO, BB);
 
+    if (auto *IEI = dyn_cast<InsertElementInst>(BBI))
+      return solveBlockValueInsertElement(IEI, BB);
+
     if (auto *EVI = dyn_cast<ExtractValueInst>(BBI))
       return solveBlockValueExtractValue(EVI, BB);
 
@@ -1038,6 +1043,24 @@ LazyValueInfoImpl::solveBlockValueIntrinsic(IntrinsicInst *II, BasicBlock *BB) {
                    MetadataVal);
 }
 
+std::optional<ValueLatticeElement>
+LazyValueInfoImpl::solveBlockValueInsertElement(InsertElementInst *IEI,
+                                                BasicBlock *BB) {
+  std::optional<ValueLatticeElement> OptEltVal =
+      getBlockValue(IEI->getOperand(1), BB, IEI);
+  if (!OptEltVal)
+    return std::nullopt;
+  ValueLatticeElement &Res = *OptEltVal;
+
+  std::optional<ValueLatticeElement> OptVecVal =
+      getBlockValue(IEI->getOperand(0), BB, IEI);
+  if (!OptVecVal)
+    return std::nullopt;
+
+  Res.mergeIn(*OptVecVal);
+  return Res;
+}
+
 std::optional<ValueLatticeElement>
 LazyValueInfoImpl::solveBlockValueExtractValue(ExtractValueInst *EVI,
                                                BasicBlock *BB) {

diff  --git a/llvm/test/Transforms/CorrelatedValuePropagation/vectors.ll b/llvm/test/Transforms/CorrelatedValuePropagation/vectors.ll
index 6254b54d42554..351a2c79cdff4 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/vectors.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/vectors.ll
@@ -327,3 +327,28 @@ join:
   %add = add <2 x i16> %phi, <i16 2, i16 3>
   ret <2 x i16> %add
 }
+
+;; Check if ICMP instruction is constant folded or not.
+define <2 x i1> @insertelement_fold1() {
+; CHECK-LABEL: define <2 x i1> @insertelement_fold1() {
+; CHECK-NEXT:    [[IE1:%.*]] = insertelement <2 x i32> poison, i32 10, i64 0
+; CHECK-NEXT:    [[IE2:%.*]] = insertelement <2 x i32> [[IE1]], i32 20, i64 1
+; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
+;
+  %ie1 = insertelement <2 x i32> poison, i32 10, i64 0
+  %ie2 = insertelement <2 x i32> %ie1, i32 20, i64 1
+  %icmp1 = icmp slt <2 x i32> %ie2, <i32 1024, i32 1024>
+  ret <2 x i1> %icmp1
+}
+
+;; Check if LVI is able to handle constant vector operands
+;; in InsertElementInst and CVP is able to fold ICMP instruction.
+define <2 x i1> @insertelement_fold2() {
+; CHECK-LABEL: define <2 x i1> @insertelement_fold2() {
+; CHECK-NEXT:    [[IE1:%.*]] = insertelement <2 x i32> <i32 poison, i32 20>, i32 10, i64 0
+; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
+;
+  %ie1 = insertelement <2 x i32> <i32 poison, i32 20>, i32 10, i64 0
+  %icmp1 = icmp slt <2 x i32> %ie1, <i32 1024, i32 1024>
+  ret <2 x i1> %icmp1
+}