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[Backend] Rewrite code for linking external library to expose more inlining opportunities (#1037)

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- Also make it cleaner. 
- And mark out the code needs to be fixed in `semantic.py`.
This commit is contained in:
Keren Zhou
2023-01-08 16:44:29 -05:00
committed by GitHub
parent ff399fbc20
commit 733301ff31
4 changed files with 129 additions and 118 deletions
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202
lib/Target/LLVMIR/LLVMIRTranslation.cpp
View File

@@ -18,6 +18,7 @@
#include "llvm/IRReader/IRReader.h"
#include "llvm/Linker/Linker.h"
#include "llvm/Support/SourceMgr.h"
#include <filesystem>
namespace mlir {
namespace triton {
@@ -26,19 +27,18 @@ namespace triton {
// information from mlir module.
struct NVVMMetadata {
int maxntidx{-1};
bool is_kernel{};
bool isKernel{};
// Free to extend with other information.
};
// Add the nvvm related metadata to LLVM IR.
void amendLLVMFunc(llvm::Function *func, const NVVMMetadata &metadata) {
static void amendLLVMFunc(llvm::Function *func, const NVVMMetadata &metadata) {
auto *module = func->getParent();
auto &ctx = func->getContext();
if (metadata.maxntidx > 0) {
auto i32_ty = llvm::IntegerType::get(ctx, 32);
auto warps =
llvm::ConstantInt::get(i32_ty, llvm::APInt(32, metadata.maxntidx));
auto warps = llvm::ConstantInt::get(llvm::IntegerType::get(ctx, 32),
llvm::APInt(32, metadata.maxntidx));
llvm::Metadata *md_args[] = {llvm::ValueAsMetadata::get(func),
llvm::MDString::get(ctx, "maxntidx"),
@@ -48,18 +48,19 @@ void amendLLVMFunc(llvm::Function *func, const NVVMMetadata &metadata) {
->addOperand(llvm::MDNode::get(ctx, md_args));
}
if (metadata.is_kernel) {
llvm::Metadata *md_args[] = {
if (metadata.isKernel) {
llvm::Metadata *mdArgs[] = {
llvm::ValueAsMetadata::get(func), llvm::MDString::get(ctx, "kernel"),
llvm::ValueAsMetadata::get(
llvm::ConstantInt::get(llvm::Type::getInt32Ty(ctx), 1))};
module->getOrInsertNamedMetadata("nvvm.annotations")
->addOperand(llvm::MDNode::get(ctx, md_args));
->addOperand(llvm::MDNode::get(ctx, mdArgs));
}
}
void extractNVVMMetadata(mlir::ModuleOp module,
llvm::DenseMap<llvm::StringRef, NVVMMetadata> *dic) {
static void
extractNVVMMetadata(mlir::ModuleOp module,
llvm::DenseMap<llvm::StringRef, NVVMMetadata> *dic) {
for (auto op : module.getOps<LLVM::LLVMFuncOp>()) {
NVVMMetadata meta;
@@ -74,7 +75,7 @@ void extractNVVMMetadata(mlir::ModuleOp module,
// kernel
if (op->hasAttr("nvvm.kernel")) {
meta.is_kernel = true;
meta.isKernel = true;
hasMetadata = true;
}
@@ -83,13 +84,109 @@ void extractNVVMMetadata(mlir::ModuleOp module,
}
}
static std::map<std::string, std::string> getExternLibs(mlir::ModuleOp module) {
std::map<std::string, std::string> externLibs;
SmallVector<LLVM::LLVMFuncOp> funcs;
module.walk([&](LLVM::LLVMFuncOp func) {
if (func.isExternal())
funcs.push_back(func);
});
for (auto &func : funcs) {
if (func.getOperation()->hasAttr("libname")) {
auto name =
func.getOperation()->getAttr("libname").dyn_cast<StringAttr>();
auto path =
func.getOperation()->getAttr("libpath").dyn_cast<StringAttr>();
if (name) {
std::string libName = name.str();
externLibs[libName] = path.str();
}
}
}
if (module.getOperation()->hasAttr("triton_gpu.externs")) {
auto dict = module.getOperation()
->getAttr("triton_gpu.externs")
.dyn_cast<DictionaryAttr>();
for (auto &attr : dict) {
externLibs[attr.getName().strref().trim().str()] =
attr.getValue().dyn_cast<StringAttr>().strref().trim().str();
}
}
if (!funcs.empty()) {
// When using the Math Dialect, it is possible that some ops (e.g., log) are
// lowered to a function call. In this case, we need to link libdevice
// using its default path:
// [triton root dir]/python/triton/language/libdevice.10.bc
// TODO(Keren): handle external linkage other than libdevice?
namespace fs = std::filesystem;
static const std::string libdevice = "libdevice";
static const std::filesystem::path path = std::filesystem::path(__FILE__)
.parent_path()
.parent_path()
.parent_path()
.parent_path() /
"python" / "triton" / "language" /
"libdevice.10.bc";
externLibs.try_emplace(libdevice, path.string());
}
return externLibs;
}
static void linkLibdevice(llvm::Module &module) {
// please check https://llvm.org/docs/NVPTXUsage.html#reflection-parameters
// this will enable fast math path in libdevice
// for example, when enable nvvm-reflect-ftz, sqrt.approx.f32 will change to
// sqrt.approx.ftz.f32
auto &ctx = module.getContext();
llvm::Type *i32 = llvm::Type::getInt32Ty(ctx);
llvm::Metadata *mdFour =
llvm::ConstantAsMetadata::get(llvm::ConstantInt::getSigned(i32, 4));
llvm::Metadata *mdName = llvm::MDString::get(ctx, "nvvm-reflect-ftz");
llvm::Metadata *mdOne =
llvm::ConstantAsMetadata::get(llvm::ConstantInt::getSigned(i32, 1));
llvm::MDNode *reflect = llvm::MDNode::get(ctx, {mdFour, mdName, mdOne});
module.addModuleFlag(reflect);
}
static bool linkExternLib(llvm::Module &module, llvm::StringRef name,
llvm::StringRef path) {
llvm::SMDiagnostic err;
auto &ctx = module.getContext();
auto extMod = llvm::parseIRFile(path, err, ctx);
if (!extMod) {
llvm::errs() << "Failed to load " << path;
return true;
}
extMod->setTargetTriple(module.getTargetTriple());
extMod->setDataLayout(module.getDataLayout());
if (llvm::Linker::linkModules(module, std::move(extMod),
llvm::Linker::Flags::LinkOnlyNeeded)) {
llvm::errs() << "Failed to link " << path;
return true;
}
if (name == "libdevice") {
linkLibdevice(module);
} else {
assert(false && "unknown extern lib: ");
}
return false;
}
std::unique_ptr<llvm::Module>
translateLLVMToLLVMIR(llvm::LLVMContext *llvmContext, mlir::ModuleOp module) {
auto context = module->getContext();
DialectRegistry registry;
mlir::registerLLVMDialectTranslation(registry);
mlir::registerNVVMDialectTranslation(registry);
context->appendDialectRegistry(registry);
module->getContext()->appendDialectRegistry(registry);
llvm::DenseMap<llvm::StringRef, NVVMMetadata> nvvmMetadata;
extractNVVMMetadata(module, &nvvmMetadata);
@@ -100,6 +197,20 @@ translateLLVMToLLVMIR(llvm::LLVMContext *llvmContext, mlir::ModuleOp module) {
return nullptr;
}
// Link external libraries before perform optimizations
// Note from libdevice users guide:
// https://docs.nvidia.com/cuda/libdevice-users-guide/basic-usage.html
// The standard process for linking with libdevice is to first link it with
// the target module, then run the standard LLVM optimization and code
// generation passes. This allows the optimizers to inline and perform
// analyses on the used library functions, and eliminate any used functions as
// dead code.
auto externLibs = getExternLibs(module);
for (auto &lib : externLibs) {
if (linkExternLib(*llvmModule, lib.first, lib.second))
return nullptr;
}
auto optPipeline = mlir::makeOptimizingTransformer(
/*optLevel=*/3, /*sizeLevel=*/0,
/*targetMachine=*/nullptr);
@@ -147,49 +258,12 @@ translateTritonGPUToLLVMIR(llvm::LLVMContext *llvmContext,
return nullptr;
}
std::map<std::string, std::string> externLibs;
SmallVector<LLVM::LLVMFuncOp> funcs;
module.walk([&](LLVM::LLVMFuncOp func) {
if (func.isExternal())
funcs.push_back(func);
});
for (auto &func : funcs) {
if (func.getOperation()->hasAttr("libname")) {
auto name =
func.getOperation()->getAttr("libname").dyn_cast<StringAttr>();
auto path =
func.getOperation()->getAttr("libpath").dyn_cast<StringAttr>();
if (name) {
std::string lib_name = name.str();
externLibs[lib_name] = path.str();
}
}
}
if (module.getOperation()->hasAttr("triton_gpu.externs")) {
auto dict = module.getOperation()
->getAttr("triton_gpu.externs")
.dyn_cast<DictionaryAttr>();
for (auto &attr : dict) {
externLibs[attr.getName().strref().trim().str()] =
attr.getValue().dyn_cast<StringAttr>().strref().trim().str();
}
}
auto llvmir = translateLLVMToLLVMIR(llvmContext, module);
if (!llvmir) {
auto llvmIR = translateLLVMToLLVMIR(llvmContext, module);
if (!llvmIR) {
llvm::errs() << "Translate to LLVM IR failed";
return nullptr;
}
llvm::SMDiagnostic err;
for (auto &lib : externLibs) {
if (linkExternLib(*llvmir, lib.second))
return nullptr;
}
return llvmir;
return llvmIR;
}
void addExternalLibs(mlir::ModuleOp &module,
@@ -211,27 +285,5 @@ void addExternalLibs(mlir::ModuleOp &module,
module.getOperation()->setAttr("triton_gpu.externs", dict);
}
bool linkExternLib(llvm::Module &module, llvm::StringRef path) {
llvm::SMDiagnostic err;
auto &ctx = module.getContext();
auto extMod = llvm::parseIRFile(path, err, ctx);
if (!extMod) {
llvm::errs() << "Failed to load " << path;
return true;
}
extMod->setTargetTriple(module.getTargetTriple());
extMod->setDataLayout(module.getDataLayout());
if (llvm::Linker::linkModules(module, std::move(extMod),
llvm::Linker::Flags::LinkOnlyNeeded)) {
llvm::errs() << "Failed to link " << path;
return true;
}
return false;
}
} // namespace triton
} // namespace mlir

41
lib/Target/PTX/PTXTranslation.cpp
View File

@@ -8,7 +8,6 @@
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Target/TargetMachine.h"
#include <filesystem>
namespace triton {
@@ -31,47 +30,7 @@ static bool findAndReplace(std::string &str, const std::string &begin,
return true;
}
static void linkExternal(llvm::Module &module) {
bool hasExternal = false;
for (auto &func : module) {
if (func.hasExternalLinkage()) {
hasExternal = true;
break;
}
}
if (hasExternal) {
namespace fs = std::filesystem;
// [triton root dir]/python/triton/language/libdevice.10.bc
static const fs::path libdevice = fs::path(__FILE__)
.parent_path()
.parent_path()
.parent_path()
.parent_path() /
"python" / "triton" / "language" /
"libdevice.10.bc";
if (mlir::triton::linkExternLib(module, libdevice.string()))
llvm::errs() << "link failed for: " << libdevice.string();
// please check https://llvm.org/docs/NVPTXUsage.html#reflection-parameters
// this will enable fast math path in libdevice
// for example, when enable nvvm-reflect-ftz, sqrt.approx.f32 will change to
// sqrt.approx.ftz.f32
auto &ctx = module.getContext();
llvm::Type *I32 = llvm::Type::getInt32Ty(ctx);
llvm::Metadata *mdFour =
llvm::ConstantAsMetadata::get(llvm::ConstantInt::getSigned(I32, 4));
llvm::Metadata *mdName = llvm::MDString::get(ctx, "nvvm-reflect-ftz");
llvm::Metadata *mdOne =
llvm::ConstantAsMetadata::get(llvm::ConstantInt::getSigned(I32, 1));
llvm::MDNode *reflect = llvm::MDNode::get(ctx, {mdFour, mdName, mdOne});
module.addModuleFlag(reflect);
}
}
std::string translateLLVMIRToPTX(llvm::Module &module, int cc, int version) {
linkExternal(module);
// LLVM version in use may not officially support target hardware
int maxNNVMCC = 75;
// options