https://github.com/kito-cheng created
https://github.com/llvm/llvm-project/pull/156397
For each intrinsic with ManualCodegen block will generate something like below:
```cpp
SegInstSEW = 0;
...
if (SegInstSEW == (unsigned)-1) {
auto PointeeType = E->getArg(4294967295)->getType()->getPointeeType();
SegInstSEW = llvm::Log2_64(getContext().getTypeSize(PointeeType));
}
```
But actually SegInstSEW is table-gen-time constant, so can remove that if-check
and directly use the constant.
This change reduce riscv_vector_builtin_cg.inc around 6600 lines (30913 to
24305) which is around 20% reduction, however seems this isn't impact the build
time much since the redundant dead branch is almost will optimized away by
compiler in early stage.
>From da7fae506e086f775ca5411e00f7f436f60d5d5f Mon Sep 17 00:00:00 2001
From: Kito Cheng <kito.ch...@sifive.com>
Date: Thu, 28 Aug 2025 18:07:01 +0800
Subject: [PATCH] [RISCV] Simplify code gen for riscv_vector_builtin_cg.inc
[NFC]
For each intrinsic with ManualCodegen block will generate something like
below:
```cpp
SegInstSEW = 0;
...
if (SegInstSEW == (unsigned)-1) {
auto PointeeType = E->getArg(4294967295)->getType()->getPointeeType();
SegInstSEW = llvm::Log2_64(getContext().getTypeSize(PointeeType));
}
```
But actually SegInstSEW is table-gen-time constant, so can remove that
if-check and directly use the constant.
This change reduce riscv_vector_builtin_cg.inc around 6600 lines
(30913 to 24305) which is around 20% reduction, however seems this isn't
impact the build time much since the redundant dead branch is almost
will optimized away by compiler in early stage.
---
clang/utils/TableGen/RISCVVEmitter.cpp | 26 +++++++++++++++-----------
1 file changed, 15 insertions(+), 11 deletions(-)
diff --git a/clang/utils/TableGen/RISCVVEmitter.cpp
b/clang/utils/TableGen/RISCVVEmitter.cpp
index 17f0c8280bdef..f73b0aecc3b6d 100644
--- a/clang/utils/TableGen/RISCVVEmitter.cpp
+++ b/clang/utils/TableGen/RISCVVEmitter.cpp
@@ -166,6 +166,8 @@ static VectorTypeModifier getTupleVTM(unsigned NF) {
static_cast<uint8_t>(VectorTypeModifier::Tuple2) + (NF - 2));
}
+static const unsigned UnknownIndex = (unsigned)-1;
+
static unsigned getIndexedLoadStorePtrIdx(const RVVIntrinsic *RVVI) {
// We need a special rule for segment load/store since the data width is not
// encoded in the intrinsic name itself.
@@ -183,7 +185,7 @@ static unsigned getIndexedLoadStorePtrIdx(const
RVVIntrinsic *RVVI) {
if (IRName.starts_with("vsoxseg") || IRName.starts_with("vsuxseg"))
return RVVI->isMasked() ? 1 : 0;
- return (unsigned)-1;
+ return UnknownIndex;
}
// This function is used to get the log2SEW of each segment load/store, this
@@ -249,19 +251,21 @@ void emitCodeGenSwitchBody(const RVVIntrinsic *RVVI,
raw_ostream &OS) {
OS << " ID = Intrinsic::riscv_" + RVVI->getIRName() + ";\n";
OS << " PolicyAttrs = " << RVVI->getPolicyAttrsBits() << ";\n";
- OS << " SegInstSEW = " << getSegInstLog2SEW(RVVI->getOverloadedName())
- << ";\n";
+ unsigned IndexedLoadStorePtrIdx = getIndexedLoadStorePtrIdx(RVVI);
+ if (IndexedLoadStorePtrIdx != UnknownIndex) {
+ OS << " {\n";
+ OS << " auto PointeeType = E->getArg(" << IndexedLoadStorePtrIdx
+ << ")->getType()->getPointeeType();\n";
+ OS << " SegInstSEW = "
+ "llvm::Log2_64(getContext().getTypeSize(PointeeType));\n";
+ OS << " }\n";
+ } else {
+ OS << " SegInstSEW = " << getSegInstLog2SEW(RVVI->getOverloadedName())
+ << ";\n";
+ }
if (RVVI->hasManualCodegen()) {
OS << "IsMasked = " << (RVVI->isMasked() ? "true" : "false") << ";\n";
-
- // Skip the non-indexed load/store and compatible header load/store.
- OS << "if (SegInstSEW == (unsigned)-1) {\n";
- OS << " auto PointeeType = E->getArg(" << getIndexedLoadStorePtrIdx(RVVI)
- << " )->getType()->getPointeeType();\n";
- OS << " SegInstSEW = "
- " llvm::Log2_64(getContext().getTypeSize(PointeeType));\n}\n";
-
OS << RVVI->getManualCodegen();
OS << "break;\n";
return;
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