[llvm] [SandboxVec][Legality] Diamond reuse multi input (PR #123426)
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Fri Jan 17 15:58:12 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: vporpo (vporpo)
<details>
<summary>Changes</summary>
This patch implements the diamond pattern where we are vectorizing toward the top of the diamond from both edges, but the second edge may use elements from a different vector or just scalar values. This requires some additional packing code (see lit test).
---
Full diff: https://github.com/llvm/llvm-project/pull/123426.diff
4 Files Affected:
- (modified) llvm/include/llvm/Transforms/Vectorize/SandboxVectorizer/Legality.h (+20-2)
- (modified) llvm/lib/Transforms/Vectorize/SandboxVectorizer/Legality.cpp (+2-1)
- (modified) llvm/lib/Transforms/Vectorize/SandboxVectorizer/Passes/BottomUpVec.cpp (+34)
- (modified) llvm/test/Transforms/SandboxVectorizer/bottomup_basic.ll (+27)
``````````diff
diff --git a/llvm/include/llvm/Transforms/Vectorize/SandboxVectorizer/Legality.h b/llvm/include/llvm/Transforms/Vectorize/SandboxVectorizer/Legality.h
index 4858ebaf0770aa..f10c535aa820ee 100644
--- a/llvm/include/llvm/Transforms/Vectorize/SandboxVectorizer/Legality.h
+++ b/llvm/include/llvm/Transforms/Vectorize/SandboxVectorizer/Legality.h
@@ -81,6 +81,7 @@ enum class LegalityResultID {
Widen, ///> Vectorize by combining scalars to a vector.
DiamondReuse, ///> Don't generate new code, reuse existing vector.
DiamondReuseWithShuffle, ///> Reuse the existing vector but add a shuffle.
+ DiamondReuseMultiInput, ///> Reuse more than one vector and/or scalars.
};
/// The reason for vectorizing or not vectorizing.
@@ -108,6 +109,8 @@ struct ToStr {
return "DiamondReuse";
case LegalityResultID::DiamondReuseWithShuffle:
return "DiamondReuseWithShuffle";
+ case LegalityResultID::DiamondReuseMultiInput:
+ return "DiamondReuseMultiInput";
}
llvm_unreachable("Unknown LegalityResultID enum");
}
@@ -287,6 +290,20 @@ class CollectDescr {
}
};
+class DiamondReuseMultiInput final : public LegalityResult {
+ friend class LegalityAnalysis;
+ CollectDescr Descr;
+ DiamondReuseMultiInput(CollectDescr &&Descr)
+ : LegalityResult(LegalityResultID::DiamondReuseMultiInput),
+ Descr(std::move(Descr)) {}
+
+public:
+ static bool classof(const LegalityResult *From) {
+ return From->getSubclassID() == LegalityResultID::DiamondReuseMultiInput;
+ }
+ const CollectDescr &getCollectDescr() const { return Descr; }
+};
+
/// Performs the legality analysis and returns a LegalityResult object.
class LegalityAnalysis {
Scheduler Sched;
@@ -312,8 +329,9 @@ class LegalityAnalysis {
: Sched(AA, Ctx), SE(SE), DL(DL), IMaps(IMaps) {}
/// A LegalityResult factory.
template <typename ResultT, typename... ArgsT>
- ResultT &createLegalityResult(ArgsT... Args) {
- ResultPool.push_back(std::unique_ptr<ResultT>(new ResultT(Args...)));
+ ResultT &createLegalityResult(ArgsT &&...Args) {
+ ResultPool.push_back(
+ std::unique_ptr<ResultT>(new ResultT(std::move(Args)...)));
return cast<ResultT>(*ResultPool.back());
}
/// Checks if it's legal to vectorize the instructions in \p Bndl.
diff --git a/llvm/lib/Transforms/Vectorize/SandboxVectorizer/Legality.cpp b/llvm/lib/Transforms/Vectorize/SandboxVectorizer/Legality.cpp
index ad3e38e2f1d923..085f4cd67ab76e 100644
--- a/llvm/lib/Transforms/Vectorize/SandboxVectorizer/Legality.cpp
+++ b/llvm/lib/Transforms/Vectorize/SandboxVectorizer/Legality.cpp
@@ -223,7 +223,8 @@ const LegalityResult &LegalityAnalysis::canVectorize(ArrayRef<Value *> Bndl,
return createLegalityResult<DiamondReuse>(Vec);
return createLegalityResult<DiamondReuseWithShuffle>(Vec, Mask);
}
- llvm_unreachable("TODO: Unimplemented");
+ return createLegalityResult<DiamondReuseMultiInput>(
+ std::move(CollectDescrs));
}
if (auto ReasonOpt = notVectorizableBasedOnOpcodesAndTypes(Bndl))
diff --git a/llvm/lib/Transforms/Vectorize/SandboxVectorizer/Passes/BottomUpVec.cpp b/llvm/lib/Transforms/Vectorize/SandboxVectorizer/Passes/BottomUpVec.cpp
index d62023ea018846..c6ab3c1942c330 100644
--- a/llvm/lib/Transforms/Vectorize/SandboxVectorizer/Passes/BottomUpVec.cpp
+++ b/llvm/lib/Transforms/Vectorize/SandboxVectorizer/Passes/BottomUpVec.cpp
@@ -308,6 +308,40 @@ Value *BottomUpVec::vectorizeRec(ArrayRef<Value *> Bndl, unsigned Depth) {
NewVec = createShuffle(VecOp, Mask);
break;
}
+ case LegalityResultID::DiamondReuseMultiInput: {
+ const auto &Descr =
+ cast<DiamondReuseMultiInput>(LegalityRes).getCollectDescr();
+ Type *ResTy = FixedVectorType::get(Bndl[0]->getType(), Bndl.size());
+
+ // TODO: Try to get WhereIt without creating a vector.
+ SmallVector<Value *, 4> DescrInstrs;
+ for (const auto &ElmDescr : Descr.getDescrs()) {
+ if (auto *I = dyn_cast<Instruction>(ElmDescr.getValue()))
+ DescrInstrs.push_back(I);
+ }
+ auto WhereIt = getInsertPointAfterInstrs(DescrInstrs);
+
+ Value *LastV = PoisonValue::get(ResTy);
+ for (auto [Lane, ElmDescr] : enumerate(Descr.getDescrs())) {
+ Value *VecOp = ElmDescr.getValue();
+ Context &Ctx = VecOp->getContext();
+ Value *ValueToInsert;
+ if (ElmDescr.needsExtract()) {
+ ConstantInt *IdxC =
+ ConstantInt::get(Type::getInt32Ty(Ctx), ElmDescr.getExtractIdx());
+ ValueToInsert = ExtractElementInst::create(VecOp, IdxC, WhereIt,
+ VecOp->getContext(), "VExt");
+ } else {
+ ValueToInsert = VecOp;
+ }
+ ConstantInt *LaneC = ConstantInt::get(Type::getInt32Ty(Ctx), Lane);
+ Value *Ins = InsertElementInst::create(LastV, ValueToInsert, LaneC,
+ WhereIt, Ctx, "VIns");
+ LastV = Ins;
+ }
+ NewVec = LastV;
+ break;
+ }
case LegalityResultID::Pack: {
// If we can't vectorize the seeds then just return.
if (Depth == 0)
diff --git a/llvm/test/Transforms/SandboxVectorizer/bottomup_basic.ll b/llvm/test/Transforms/SandboxVectorizer/bottomup_basic.ll
index a3798af8399087..5b389e25d70d95 100644
--- a/llvm/test/Transforms/SandboxVectorizer/bottomup_basic.ll
+++ b/llvm/test/Transforms/SandboxVectorizer/bottomup_basic.ll
@@ -242,3 +242,30 @@ define void @diamondWithShuffle(ptr %ptr) {
store float %sub1, ptr %ptr1
ret void
}
+
+define void @diamondMultiInput(ptr %ptr, ptr %ptrX) {
+; CHECK-LABEL: define void @diamondMultiInput(
+; CHECK-SAME: ptr [[PTR:%.*]], ptr [[PTRX:%.*]]) {
+; CHECK-NEXT: [[PTR0:%.*]] = getelementptr float, ptr [[PTR]], i32 0
+; CHECK-NEXT: [[VECL:%.*]] = load <2 x float>, ptr [[PTR0]], align 4
+; CHECK-NEXT: [[LDX:%.*]] = load float, ptr [[PTRX]], align 4
+; CHECK-NEXT: [[VINS:%.*]] = insertelement <2 x float> poison, float [[LDX]], i32 0
+; CHECK-NEXT: [[VEXT:%.*]] = extractelement <2 x float> [[VECL]], i32 0
+; CHECK-NEXT: [[VINS1:%.*]] = insertelement <2 x float> [[VINS]], float [[VEXT]], i32 1
+; CHECK-NEXT: [[VEC:%.*]] = fsub <2 x float> [[VECL]], [[VINS1]]
+; CHECK-NEXT: store <2 x float> [[VEC]], ptr [[PTR0]], align 4
+; CHECK-NEXT: ret void
+;
+ %ptr0 = getelementptr float, ptr %ptr, i32 0
+ %ptr1 = getelementptr float, ptr %ptr, i32 1
+ %ld0 = load float, ptr %ptr0
+ %ld1 = load float, ptr %ptr1
+
+ %ldX = load float, ptr %ptrX
+
+ %sub0 = fsub float %ld0, %ldX
+ %sub1 = fsub float %ld1, %ld0
+ store float %sub0, ptr %ptr0
+ store float %sub1, ptr %ptr1
+ ret void
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/123426
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