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//===- AsyncToLLVM.cpp - Convert Async to LLVM dialect --------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "mlir/Conversion/AsyncToLLVM/AsyncToLLVM.h"
#include "../PassDetail.h"
#include "mlir/Dialect/Async/IR/Async.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/Dialect/StandardOps/IR/Ops.h"
#include "mlir/IR/BlockAndValueMapping.h"
#include "mlir/IR/Builders.h"
#include "mlir/IR/TypeUtilities.h"
#include "mlir/Pass/Pass.h"
#include "mlir/Transforms/DialectConversion.h"
#include "mlir/Transforms/RegionUtils.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Support/FormatVariadic.h"
#define DEBUG_TYPE "convert-async-to-llvm"
using namespace mlir;
using namespace mlir::async;
// Prefix for functions outlined from `async.execute` op regions.
static constexpr const char kAsyncFnPrefix[] = "async_execute_fn";
//===----------------------------------------------------------------------===//
// Async Runtime C API declaration.
//===----------------------------------------------------------------------===//
static constexpr const char *kAddRef = "mlirAsyncRuntimeAddRef";
static constexpr const char *kDropRef = "mlirAsyncRuntimeDropRef";
static constexpr const char *kCreateToken = "mlirAsyncRuntimeCreateToken";
static constexpr const char *kCreateGroup = "mlirAsyncRuntimeCreateGroup";
static constexpr const char *kEmplaceToken = "mlirAsyncRuntimeEmplaceToken";
static constexpr const char *kAwaitToken = "mlirAsyncRuntimeAwaitToken";
static constexpr const char *kAwaitGroup = "mlirAsyncRuntimeAwaitAllInGroup";
static constexpr const char *kExecute = "mlirAsyncRuntimeExecute";
static constexpr const char *kAddTokenToGroup =
"mlirAsyncRuntimeAddTokenToGroup";
static constexpr const char *kAwaitAndExecute =
"mlirAsyncRuntimeAwaitTokenAndExecute";
static constexpr const char *kAwaitAllAndExecute =
"mlirAsyncRuntimeAwaitAllInGroupAndExecute";
namespace {
// Async Runtime API function types.
struct AsyncAPI {
static FunctionType addOrDropRefFunctionType(MLIRContext *ctx) {
auto ref = LLVM::LLVMType::getInt8PtrTy(ctx);
auto count = IntegerType::get(32, ctx);
return FunctionType::get({ref, count}, {}, ctx);
}
static FunctionType createTokenFunctionType(MLIRContext *ctx) {
return FunctionType::get({}, {TokenType::get(ctx)}, ctx);
}
static FunctionType createGroupFunctionType(MLIRContext *ctx) {
return FunctionType::get({}, {GroupType::get(ctx)}, ctx);
}
static FunctionType emplaceTokenFunctionType(MLIRContext *ctx) {
return FunctionType::get({TokenType::get(ctx)}, {}, ctx);
}
static FunctionType awaitTokenFunctionType(MLIRContext *ctx) {
return FunctionType::get({TokenType::get(ctx)}, {}, ctx);
}
static FunctionType awaitGroupFunctionType(MLIRContext *ctx) {
return FunctionType::get({GroupType::get(ctx)}, {}, ctx);
}
static FunctionType executeFunctionType(MLIRContext *ctx) {
auto hdl = LLVM::LLVMType::getInt8PtrTy(ctx);
auto resume = resumeFunctionType(ctx).getPointerTo();
return FunctionType::get({hdl, resume}, {}, ctx);
}
static FunctionType addTokenToGroupFunctionType(MLIRContext *ctx) {
auto i64 = IntegerType::get(64, ctx);
return FunctionType::get({TokenType::get(ctx), GroupType::get(ctx)}, {i64},
ctx);
}
static FunctionType awaitAndExecuteFunctionType(MLIRContext *ctx) {
auto hdl = LLVM::LLVMType::getInt8PtrTy(ctx);
auto resume = resumeFunctionType(ctx).getPointerTo();
return FunctionType::get({TokenType::get(ctx), hdl, resume}, {}, ctx);
}
static FunctionType awaitAllAndExecuteFunctionType(MLIRContext *ctx) {
auto hdl = LLVM::LLVMType::getInt8PtrTy(ctx);
auto resume = resumeFunctionType(ctx).getPointerTo();
return FunctionType::get({GroupType::get(ctx), hdl, resume}, {}, ctx);
}
// Auxiliary coroutine resume intrinsic wrapper.
static LLVM::LLVMType resumeFunctionType(MLIRContext *ctx) {
auto voidTy = LLVM::LLVMType::getVoidTy(ctx);
auto i8Ptr = LLVM::LLVMType::getInt8PtrTy(ctx);
return LLVM::LLVMType::getFunctionTy(voidTy, {i8Ptr}, false);
}
};
} // namespace
// Adds Async Runtime C API declarations to the module.
static void addAsyncRuntimeApiDeclarations(ModuleOp module) {
auto builder = OpBuilder::atBlockTerminator(module.getBody());
auto addFuncDecl = [&](StringRef name, FunctionType type) {
if (module.lookupSymbol(name))
return;
builder.create<FuncOp>(module.getLoc(), name, type).setPrivate();
};
MLIRContext *ctx = module.getContext();
addFuncDecl(kAddRef, AsyncAPI::addOrDropRefFunctionType(ctx));
addFuncDecl(kDropRef, AsyncAPI::addOrDropRefFunctionType(ctx));
addFuncDecl(kCreateToken, AsyncAPI::createTokenFunctionType(ctx));
addFuncDecl(kCreateGroup, AsyncAPI::createGroupFunctionType(ctx));
addFuncDecl(kEmplaceToken, AsyncAPI::emplaceTokenFunctionType(ctx));
addFuncDecl(kAwaitToken, AsyncAPI::awaitTokenFunctionType(ctx));
addFuncDecl(kAwaitGroup, AsyncAPI::awaitGroupFunctionType(ctx));
addFuncDecl(kExecute, AsyncAPI::executeFunctionType(ctx));
addFuncDecl(kAddTokenToGroup, AsyncAPI::addTokenToGroupFunctionType(ctx));
addFuncDecl(kAwaitAndExecute, AsyncAPI::awaitAndExecuteFunctionType(ctx));
addFuncDecl(kAwaitAllAndExecute,
AsyncAPI::awaitAllAndExecuteFunctionType(ctx));
}
//===----------------------------------------------------------------------===//
// LLVM coroutines intrinsics declarations.
//===----------------------------------------------------------------------===//
static constexpr const char *kCoroId = "llvm.coro.id";
static constexpr const char *kCoroSizeI64 = "llvm.coro.size.i64";
static constexpr const char *kCoroBegin = "llvm.coro.begin";
static constexpr const char *kCoroSave = "llvm.coro.save";
static constexpr const char *kCoroSuspend = "llvm.coro.suspend";
static constexpr const char *kCoroEnd = "llvm.coro.end";
static constexpr const char *kCoroFree = "llvm.coro.free";
static constexpr const char *kCoroResume = "llvm.coro.resume";
/// Adds an LLVM function declaration to a module.
static void addLLVMFuncDecl(ModuleOp module, OpBuilder &builder, StringRef name,
LLVM::LLVMType ret,
ArrayRef<LLVM::LLVMType> params) {
if (module.lookupSymbol(name))
return;
LLVM::LLVMType type = LLVM::LLVMType::getFunctionTy(ret, params, false);
builder.create<LLVM::LLVMFuncOp>(module.getLoc(), name, type);
}
/// Adds coroutine intrinsics declarations to the module.
static void addCoroutineIntrinsicsDeclarations(ModuleOp module) {
using namespace mlir::LLVM;
MLIRContext *ctx = module.getContext();
OpBuilder builder(module.getBody()->getTerminator());
auto token = LLVMTokenType::get(ctx);
auto voidTy = LLVMType::getVoidTy(ctx);
auto i8 = LLVMType::getInt8Ty(ctx);
auto i1 = LLVMType::getInt1Ty(ctx);
auto i32 = LLVMType::getInt32Ty(ctx);
auto i64 = LLVMType::getInt64Ty(ctx);
auto i8Ptr = LLVMType::getInt8PtrTy(ctx);
addLLVMFuncDecl(module, builder, kCoroId, token, {i32, i8Ptr, i8Ptr, i8Ptr});
addLLVMFuncDecl(module, builder, kCoroSizeI64, i64, {});
addLLVMFuncDecl(module, builder, kCoroBegin, i8Ptr, {token, i8Ptr});
addLLVMFuncDecl(module, builder, kCoroSave, token, {i8Ptr});
addLLVMFuncDecl(module, builder, kCoroSuspend, i8, {token, i1});
addLLVMFuncDecl(module, builder, kCoroEnd, i1, {i8Ptr, i1});
addLLVMFuncDecl(module, builder, kCoroFree, i8Ptr, {token, i8Ptr});
addLLVMFuncDecl(module, builder, kCoroResume, voidTy, {i8Ptr});
}
//===----------------------------------------------------------------------===//
// Add malloc/free declarations to the module.
//===----------------------------------------------------------------------===//
static constexpr const char *kMalloc = "malloc";
static constexpr const char *kFree = "free";
/// Adds malloc/free declarations to the module.
static void addCRuntimeDeclarations(ModuleOp module) {
using namespace mlir::LLVM;
MLIRContext *ctx = module.getContext();
OpBuilder builder(module.getBody()->getTerminator());
auto voidTy = LLVMType::getVoidTy(ctx);
auto i64 = LLVMType::getInt64Ty(ctx);
auto i8Ptr = LLVMType::getInt8PtrTy(ctx);
addLLVMFuncDecl(module, builder, kMalloc, i8Ptr, {i64});
addLLVMFuncDecl(module, builder, kFree, voidTy, {i8Ptr});
}
//===----------------------------------------------------------------------===//
// Coroutine resume function wrapper.
//===----------------------------------------------------------------------===//
static constexpr const char *kResume = "__resume";
// A function that takes a coroutine handle and calls a `llvm.coro.resume`
// intrinsics. We need this function to be able to pass it to the async
// runtime execute API.
static void addResumeFunction(ModuleOp module) {
MLIRContext *ctx = module.getContext();
OpBuilder moduleBuilder(module.getBody()->getTerminator());
Location loc = module.getLoc();
if (module.lookupSymbol(kResume))
return;
auto voidTy = LLVM::LLVMType::getVoidTy(ctx);
auto i8Ptr = LLVM::LLVMType::getInt8PtrTy(ctx);
auto resumeOp = moduleBuilder.create<LLVM::LLVMFuncOp>(
loc, kResume, LLVM::LLVMType::getFunctionTy(voidTy, {i8Ptr}, false));
resumeOp.setPrivate();
auto *block = resumeOp.addEntryBlock();
OpBuilder blockBuilder = OpBuilder::atBlockEnd(block);
blockBuilder.create<LLVM::CallOp>(loc, TypeRange(),
blockBuilder.getSymbolRefAttr(kCoroResume),
resumeOp.getArgument(0));
blockBuilder.create<LLVM::ReturnOp>(loc, ValueRange());
}
//===----------------------------------------------------------------------===//
// async.execute op outlining to the coroutine functions.
//===----------------------------------------------------------------------===//
// Function targeted for coroutine transformation has two additional blocks at
// the end: coroutine cleanup and coroutine suspension.
//
// async.await op lowering additionaly creates a resume block for each
// operation to enable non-blocking waiting via coroutine suspension.
namespace {
struct CoroMachinery {
Value asyncToken;
Value coroHandle;
Block *cleanup;
Block *suspend;
};
} // namespace
// Builds an coroutine template compatible with LLVM coroutines lowering.
//
// - `entry` block sets up the coroutine.
// - `cleanup` block cleans up the coroutine state.
// - `suspend block after the @llvm.coro.end() defines what value will be
// returned to the initial caller of a coroutine. Everything before the
// @llvm.coro.end() will be executed at every suspension point.
//
// Coroutine structure (only the important bits):
//
// func @async_execute_fn(<function-arguments>) -> !async.token {
// ^entryBlock(<function-arguments>):
// %token = <async token> : !async.token // create async runtime token
// %hdl = llvm.call @llvm.coro.id(...) // create a coroutine handle
// br ^cleanup
//
// ^cleanup:
// llvm.call @llvm.coro.free(...) // delete coroutine state
// br ^suspend
//
// ^suspend:
// llvm.call @llvm.coro.end(...) // marks the end of a coroutine
// return %token : !async.token
// }
//
// The actual code for the async.execute operation body region will be inserted
// before the entry block terminator.
//
//
static CoroMachinery setupCoroMachinery(FuncOp func) {
assert(func.getBody().empty() && "Function must have empty body");
MLIRContext *ctx = func.getContext();
auto token = LLVM::LLVMTokenType::get(ctx);
auto i1 = LLVM::LLVMType::getInt1Ty(ctx);
auto i32 = LLVM::LLVMType::getInt32Ty(ctx);
auto i64 = LLVM::LLVMType::getInt64Ty(ctx);
auto i8Ptr = LLVM::LLVMType::getInt8PtrTy(ctx);
Block *entryBlock = func.addEntryBlock();
Location loc = func.getBody().getLoc();
OpBuilder builder = OpBuilder::atBlockBegin(entryBlock);
// ------------------------------------------------------------------------ //
// Allocate async tokens/values that we will return from a ramp function.
// ------------------------------------------------------------------------ //
auto createToken =
builder.create<CallOp>(loc, kCreateToken, TokenType::get(ctx));
// ------------------------------------------------------------------------ //
// Initialize coroutine: allocate frame, get coroutine handle.
// ------------------------------------------------------------------------ //
// Constants for initializing coroutine frame.
auto constZero =
builder.create<LLVM::ConstantOp>(loc, i32, builder.getI32IntegerAttr(0));
auto constFalse =
builder.create<LLVM::ConstantOp>(loc, i1, builder.getBoolAttr(false));
auto nullPtr = builder.create<LLVM::NullOp>(loc, i8Ptr);
// Get coroutine id: @llvm.coro.id
auto coroId = builder.create<LLVM::CallOp>(
loc, token, builder.getSymbolRefAttr(kCoroId),
ValueRange({constZero, nullPtr, nullPtr, nullPtr}));
// Get coroutine frame size: @llvm.coro.size.i64
auto coroSize = builder.create<LLVM::CallOp>(
loc, i64, builder.getSymbolRefAttr(kCoroSizeI64), ValueRange());
// Allocate memory for coroutine frame.
auto coroAlloc = builder.create<LLVM::CallOp>(
loc, i8Ptr, builder.getSymbolRefAttr(kMalloc),
ValueRange(coroSize.getResult(0)));
// Begin a coroutine: @llvm.coro.begin
auto coroHdl = builder.create<LLVM::CallOp>(
loc, i8Ptr, builder.getSymbolRefAttr(kCoroBegin),
ValueRange({coroId.getResult(0), coroAlloc.getResult(0)}));
Block *cleanupBlock = func.addBlock();
Block *suspendBlock = func.addBlock();
// ------------------------------------------------------------------------ //
// Coroutine cleanup block: deallocate coroutine frame, free the memory.
// ------------------------------------------------------------------------ //
builder.setInsertionPointToStart(cleanupBlock);
// Get a pointer to the coroutine frame memory: @llvm.coro.free.
auto coroMem = builder.create<LLVM::CallOp>(
loc, i8Ptr, builder.getSymbolRefAttr(kCoroFree),
ValueRange({coroId.getResult(0), coroHdl.getResult(0)}));
// Free the memory.
builder.create<LLVM::CallOp>(loc, TypeRange(),
builder.getSymbolRefAttr(kFree),
ValueRange(coroMem.getResult(0)));
// Branch into the suspend block.
builder.create<BranchOp>(loc, suspendBlock);
// ------------------------------------------------------------------------ //
// Coroutine suspend block: mark the end of a coroutine and return allocated
// async token.
// ------------------------------------------------------------------------ //
builder.setInsertionPointToStart(suspendBlock);
// Mark the end of a coroutine: @llvm.coro.end.
builder.create<LLVM::CallOp>(loc, i1, builder.getSymbolRefAttr(kCoroEnd),
ValueRange({coroHdl.getResult(0), constFalse}));
// Return created `async.token` from the suspend block. This will be the
// return value of a coroutine ramp function.
builder.create<ReturnOp>(loc, createToken.getResult(0));
// Branch from the entry block to the cleanup block to create a valid CFG.
builder.setInsertionPointToEnd(entryBlock);
builder.create<BranchOp>(loc, cleanupBlock);
// `async.await` op lowering will create resume blocks for async
// continuations, and will conditionally branch to cleanup or suspend blocks.
return {createToken.getResult(0), coroHdl.getResult(0), cleanupBlock,
suspendBlock};
}
// Add a LLVM coroutine suspension point to the end of suspended block, to
// resume execution in resume block. The caller is responsible for creating the
// two suspended/resume blocks with the desired ops contained in each block.
// This function merely provides the required control flow logic.
//
// `coroState` must be a value returned from the call to @llvm.coro.save(...)
// intrinsic (saved coroutine state).
//
// Before:
//
// ^bb0:
// "opBefore"(...)
// "op"(...)
// ^cleanup: ...
// ^suspend: ...
// ^resume:
// "op"(...)
//
// After:
//
// ^bb0:
// "opBefore"(...)
// %suspend = llmv.call @llvm.coro.suspend(...)
// switch %suspend [-1: ^suspend, 0: ^resume, 1: ^cleanup]
// ^resume:
// "op"(...)
// ^cleanup: ...
// ^suspend: ...
//
static void addSuspensionPoint(CoroMachinery coro, Value coroState,
Operation *op, Block *suspended, Block *resume,
OpBuilder &builder) {
Location loc = op->getLoc();
MLIRContext *ctx = op->getContext();
auto i1 = LLVM::LLVMType::getInt1Ty(ctx);
auto i8 = LLVM::LLVMType::getInt8Ty(ctx);
// Add a coroutine suspension in place of original `op` in the split block.
OpBuilder::InsertionGuard guard(builder);
builder.setInsertionPointToEnd(suspended);
auto constFalse =
builder.create<LLVM::ConstantOp>(loc, i1, builder.getBoolAttr(false));
// Suspend a coroutine: @llvm.coro.suspend
auto coroSuspend = builder.create<LLVM::CallOp>(
loc, i8, builder.getSymbolRefAttr(kCoroSuspend),
ValueRange({coroState, constFalse}));
// After a suspension point decide if we should branch into resume, cleanup
// or suspend block of the coroutine (see @llvm.coro.suspend return code
// documentation).
auto constZero =
builder.create<LLVM::ConstantOp>(loc, i8, builder.getI8IntegerAttr(0));
auto constNegOne =
builder.create<LLVM::ConstantOp>(loc, i8, builder.getI8IntegerAttr(-1));
Block *resumeOrCleanup = builder.createBlock(resume);
// Suspend the coroutine ...?
builder.setInsertionPointToEnd(suspended);
auto isNegOne = builder.create<LLVM::ICmpOp>(
loc, LLVM::ICmpPredicate::eq, coroSuspend.getResult(0), constNegOne);
builder.create<LLVM::CondBrOp>(loc, isNegOne, /*trueDest=*/coro.suspend,
/*falseDest=*/resumeOrCleanup);
// ... or resume or cleanup the coroutine?
builder.setInsertionPointToStart(resumeOrCleanup);
auto isZero = builder.create<LLVM::ICmpOp>(
loc, LLVM::ICmpPredicate::eq, coroSuspend.getResult(0), constZero);
builder.create<LLVM::CondBrOp>(loc, isZero, /*trueDest=*/resume,
/*falseDest=*/coro.cleanup);
}
// Outline the body region attached to the `async.execute` op into a standalone
// function.
//
// Note that this is not reversible transformation.
static std::pair<FuncOp, CoroMachinery>
outlineExecuteOp(SymbolTable &symbolTable, ExecuteOp execute) {
ModuleOp module = execute->getParentOfType<ModuleOp>();
MLIRContext *ctx = module.getContext();
Location loc = execute.getLoc();
OpBuilder moduleBuilder(module.getBody()->getTerminator());
// Collect all outlined function inputs.
llvm::SetVector<mlir::Value> functionInputs(execute.dependencies().begin(),
execute.dependencies().end());
getUsedValuesDefinedAbove(execute.body(), functionInputs);
// Collect types for the outlined function inputs and outputs.
auto typesRange = llvm::map_range(
functionInputs, [](Value value) { return value.getType(); });
SmallVector<Type, 4> inputTypes(typesRange.begin(), typesRange.end());
auto outputTypes = execute.getResultTypes();
auto funcType = moduleBuilder.getFunctionType(inputTypes, outputTypes);
auto funcAttrs = ArrayRef<NamedAttribute>();
// TODO: Derive outlined function name from the parent FuncOp (support
// multiple nested async.execute operations).
FuncOp func = FuncOp::create(loc, kAsyncFnPrefix, funcType, funcAttrs);
symbolTable.insert(func, moduleBuilder.getInsertionPoint());
SymbolTable::setSymbolVisibility(func, SymbolTable::Visibility::Private);
// Prepare a function for coroutine lowering by adding entry/cleanup/suspend
// blocks, adding llvm.coro instrinsics and setting up control flow.
CoroMachinery coro = setupCoroMachinery(func);
// Suspend async function at the end of an entry block, and resume it using
// Async execute API (execution will be resumed in a thread managed by the
// async runtime).
Block *entryBlock = &func.getBlocks().front();
OpBuilder builder = OpBuilder::atBlockTerminator(entryBlock);
// A pointer to coroutine resume intrinsic wrapper.
auto resumeFnTy = AsyncAPI::resumeFunctionType(ctx);
auto resumePtr = builder.create<LLVM::AddressOfOp>(
loc, resumeFnTy.getPointerTo(), kResume);
// Save the coroutine state: @llvm.coro.save
auto coroSave = builder.create<LLVM::CallOp>(
loc, LLVM::LLVMTokenType::get(ctx), builder.getSymbolRefAttr(kCoroSave),
ValueRange({coro.coroHandle}));
// Call async runtime API to execute a coroutine in the managed thread.
SmallVector<Value, 2> executeArgs = {coro.coroHandle, resumePtr.res()};
builder.create<CallOp>(loc, TypeRange(), kExecute, executeArgs);
// Split the entry block before the terminator.
auto *terminatorOp = entryBlock->getTerminator();
Block *suspended = terminatorOp->getBlock();
Block *resume = suspended->splitBlock(terminatorOp);
addSuspensionPoint(coro, coroSave.getResult(0), terminatorOp, suspended,
resume, builder);
// Await on all dependencies before starting to execute the body region.
builder.setInsertionPointToStart(resume);
for (size_t i = 0; i < execute.dependencies().size(); ++i)
builder.create<AwaitOp>(loc, func.getArgument(i));
// Map from function inputs defined above the execute op to the function
// arguments.
BlockAndValueMapping valueMapping;
valueMapping.map(functionInputs, func.getArguments());
// Clone all operations from the execute operation body into the outlined
// function body, and replace all `async.yield` operations with a call
// to async runtime to emplace the result token.
for (Operation &op : execute.body().getOps()) {
if (isa<async::YieldOp>(op)) {
builder.create<CallOp>(loc, kEmplaceToken, TypeRange(), coro.asyncToken);
continue;
}
builder.clone(op, valueMapping);
}
// Replace the original `async.execute` with a call to outlined function.
OpBuilder callBuilder(execute);
auto callOutlinedFunc =
callBuilder.create<CallOp>(loc, func.getName(), execute.getResultTypes(),
functionInputs.getArrayRef());
execute.replaceAllUsesWith(callOutlinedFunc.getResults());
execute.erase();
return {func, coro};
}
//===----------------------------------------------------------------------===//
// Convert Async dialect types to LLVM types.
//===----------------------------------------------------------------------===//
namespace {
class AsyncRuntimeTypeConverter : public TypeConverter {
public:
AsyncRuntimeTypeConverter() { addConversion(convertType); }
static Type convertType(Type type) {
MLIRContext *ctx = type.getContext();
// Convert async tokens and groups to opaque pointers.
if (type.isa<TokenType, GroupType>())
return LLVM::LLVMType::getInt8PtrTy(ctx);
return type;
}
};
} // namespace
//===----------------------------------------------------------------------===//
// Convert types for all call operations to lowered async types.
//===----------------------------------------------------------------------===//
namespace {
class CallOpOpConversion : public ConversionPattern {
public:
explicit CallOpOpConversion(MLIRContext *ctx)
: ConversionPattern(CallOp::getOperationName(), 1, ctx) {}
LogicalResult
matchAndRewrite(Operation *op, ArrayRef<Value> operands,
ConversionPatternRewriter &rewriter) const override {
AsyncRuntimeTypeConverter converter;
SmallVector<Type, 5> resultTypes;
converter.convertTypes(op->getResultTypes(), resultTypes);
CallOp call = cast<CallOp>(op);
rewriter.replaceOpWithNewOp<CallOp>(op, resultTypes, call.callee(),
operands);
return success();
}
};
} // namespace
//===----------------------------------------------------------------------===//
// Async reference counting ops lowering (`async.add_ref` and `async.drop_ref`
// to the corresponding API calls).
//===----------------------------------------------------------------------===//
namespace {
template <typename RefCountingOp>
class RefCountingOpLowering : public ConversionPattern {
public:
explicit RefCountingOpLowering(MLIRContext *ctx, StringRef apiFunctionName)
: ConversionPattern(RefCountingOp::getOperationName(), 1, ctx),
apiFunctionName(apiFunctionName) {}
LogicalResult
matchAndRewrite(Operation *op, ArrayRef<Value> operands,
ConversionPatternRewriter &rewriter) const override {
RefCountingOp refCountingOp = cast<RefCountingOp>(op);
auto count = rewriter.create<ConstantOp>(
op->getLoc(), rewriter.getI32Type(),
rewriter.getI32IntegerAttr(refCountingOp.count()));
rewriter.replaceOpWithNewOp<CallOp>(op, TypeRange(), apiFunctionName,
ValueRange({operands[0], count}));
return success();
}
private:
StringRef apiFunctionName;
};
// async.drop_ref op lowering to mlirAsyncRuntimeDropRef function call.
class AddRefOpLowering : public RefCountingOpLowering<AddRefOp> {
public:
explicit AddRefOpLowering(MLIRContext *ctx)
: RefCountingOpLowering(ctx, kAddRef) {}
};
// async.create_group op lowering to mlirAsyncRuntimeCreateGroup function call.
class DropRefOpLowering : public RefCountingOpLowering<DropRefOp> {
public:
explicit DropRefOpLowering(MLIRContext *ctx)
: RefCountingOpLowering(ctx, kDropRef) {}
};
} // namespace
//===----------------------------------------------------------------------===//
// async.create_group op lowering to mlirAsyncRuntimeCreateGroup function call.
//===----------------------------------------------------------------------===//
namespace {
class CreateGroupOpLowering : public ConversionPattern {
public:
explicit CreateGroupOpLowering(MLIRContext *ctx)
: ConversionPattern(CreateGroupOp::getOperationName(), 1, ctx) {}
LogicalResult
matchAndRewrite(Operation *op, ArrayRef<Value> operands,
ConversionPatternRewriter &rewriter) const override {
auto retTy = GroupType::get(op->getContext());
rewriter.replaceOpWithNewOp<CallOp>(op, kCreateGroup, retTy);
return success();
}
};
} // namespace
//===----------------------------------------------------------------------===//
// async.add_to_group op lowering to runtime function call.
//===----------------------------------------------------------------------===//
namespace {
class AddToGroupOpLowering : public ConversionPattern {
public:
explicit AddToGroupOpLowering(MLIRContext *ctx)
: ConversionPattern(AddToGroupOp::getOperationName(), 1, ctx) {}
LogicalResult
matchAndRewrite(Operation *op, ArrayRef<Value> operands,
ConversionPatternRewriter &rewriter) const override {
// Currently we can only add tokens to the group.
auto addToGroup = cast<AddToGroupOp>(op);
if (!addToGroup.operand().getType().isa<TokenType>())
return failure();
auto i64 = IntegerType::get(64, op->getContext());
rewriter.replaceOpWithNewOp<CallOp>(op, kAddTokenToGroup, i64, operands);
return success();
}
};
} // namespace
//===----------------------------------------------------------------------===//
// async.await and async.await_all op lowerings to the corresponding async
// runtime function calls.
//===----------------------------------------------------------------------===//
namespace {
template <typename AwaitType, typename AwaitableType>
class AwaitOpLoweringBase : public ConversionPattern {
protected:
explicit AwaitOpLoweringBase(
MLIRContext *ctx,
const llvm::DenseMap<FuncOp, CoroMachinery> &outlinedFunctions,
StringRef blockingAwaitFuncName, StringRef coroAwaitFuncName)
: ConversionPattern(AwaitType::getOperationName(), 1, ctx),
outlinedFunctions(outlinedFunctions),
blockingAwaitFuncName(blockingAwaitFuncName),
coroAwaitFuncName(coroAwaitFuncName) {}
public:
LogicalResult
matchAndRewrite(Operation *op, ArrayRef<Value> operands,
ConversionPatternRewriter &rewriter) const override {
// We can only await on one the `AwaitableType` (for `await` it can be
// only a `token`, for `await_all` it is a `group`).
auto await = cast<AwaitType>(op);
if (!await.operand().getType().template isa<AwaitableType>())
return failure();
// Check if await operation is inside the outlined coroutine function.
auto func = await->template getParentOfType<FuncOp>();
auto outlined = outlinedFunctions.find(func);
const bool isInCoroutine = outlined != outlinedFunctions.end();
Location loc = op->getLoc();
// Inside regular function we convert await operation to the blocking
// async API await function call.
if (!isInCoroutine)
rewriter.create<CallOp>(loc, TypeRange(), blockingAwaitFuncName,
ValueRange(operands[0]));
// Inside the coroutine we convert await operation into coroutine suspension
// point, and resume execution asynchronously.
if (isInCoroutine) {
const CoroMachinery &coro = outlined->getSecond();
OpBuilder builder(op, rewriter.getListener());
MLIRContext *ctx = op->getContext();
// A pointer to coroutine resume intrinsic wrapper.
auto resumeFnTy = AsyncAPI::resumeFunctionType(ctx);
auto resumePtr = builder.create<LLVM::AddressOfOp>(
loc, resumeFnTy.getPointerTo(), kResume);
// Save the coroutine state: @llvm.coro.save
auto coroSave = builder.create<LLVM::CallOp>(
loc, LLVM::LLVMTokenType::get(ctx),
builder.getSymbolRefAttr(kCoroSave), ValueRange(coro.coroHandle));
// Call async runtime API to resume a coroutine in the managed thread when
// the async await argument becomes ready.
SmallVector<Value, 3> awaitAndExecuteArgs = {operands[0], coro.coroHandle,
resumePtr.res()};
builder.create<CallOp>(loc, TypeRange(), coroAwaitFuncName,
awaitAndExecuteArgs);
Block *suspended = op->getBlock();
// Split the entry block before the await operation.
Block *resume = rewriter.splitBlock(suspended, Block::iterator(op));
addSuspensionPoint(coro, coroSave.getResult(0), op, suspended, resume,
builder);
}
// Original operation was replaced by function call or suspension point.
rewriter.eraseOp(op);
return success();
}
private:
const llvm::DenseMap<FuncOp, CoroMachinery> &outlinedFunctions;
StringRef blockingAwaitFuncName;
StringRef coroAwaitFuncName;
};
// Lowering for `async.await` operation (only token operands are supported).
class AwaitOpLowering : public AwaitOpLoweringBase<AwaitOp, TokenType> {
using Base = AwaitOpLoweringBase<AwaitOp, TokenType>;
public:
explicit AwaitOpLowering(
MLIRContext *ctx,
const llvm::DenseMap<FuncOp, CoroMachinery> &outlinedFunctions)
: Base(ctx, outlinedFunctions, kAwaitToken, kAwaitAndExecute) {}
};
// Lowering for `async.await_all` operation.
class AwaitAllOpLowering : public AwaitOpLoweringBase<AwaitAllOp, GroupType> {
using Base = AwaitOpLoweringBase<AwaitAllOp, GroupType>;
public:
explicit AwaitAllOpLowering(
MLIRContext *ctx,
const llvm::DenseMap<FuncOp, CoroMachinery> &outlinedFunctions)
: Base(ctx, outlinedFunctions, kAwaitGroup, kAwaitAllAndExecute) {}
};
} // namespace
//===----------------------------------------------------------------------===//
namespace {
struct ConvertAsyncToLLVMPass
: public ConvertAsyncToLLVMBase<ConvertAsyncToLLVMPass> {
void runOnOperation() override;
};
void ConvertAsyncToLLVMPass::runOnOperation() {
ModuleOp module = getOperation();
SymbolTable symbolTable(module);
// Outline all `async.execute` body regions into async functions (coroutines).
llvm::DenseMap<FuncOp, CoroMachinery> outlinedFunctions;
WalkResult outlineResult = module.walk([&](ExecuteOp execute) {
// We currently do not support execute operations that have async value
// operands or produce async results.
if (!execute.operands().empty() || !execute.results().empty()) {
execute.emitOpError("can't outline async.execute op with async value "
"operands or returned async results");
return WalkResult::interrupt();
}
outlinedFunctions.insert(outlineExecuteOp(symbolTable, execute));
return WalkResult::advance();
});
// Failed to outline all async execute operations.
if (outlineResult.wasInterrupted()) {
signalPassFailure();
return;
}
LLVM_DEBUG({
llvm::dbgs() << "Outlined " << outlinedFunctions.size()
<< " async functions\n";
});
// Add declarations for all functions required by the coroutines lowering.
addResumeFunction(module);
addAsyncRuntimeApiDeclarations(module);
addCoroutineIntrinsicsDeclarations(module);
addCRuntimeDeclarations(module);
MLIRContext *ctx = &getContext();
// Convert async dialect types and operations to LLVM dialect.
AsyncRuntimeTypeConverter converter;
OwningRewritePatternList patterns;
populateFuncOpTypeConversionPattern(patterns, ctx, converter);
patterns.insert<CallOpOpConversion>(ctx);
patterns.insert<AddRefOpLowering, DropRefOpLowering>(ctx);
patterns.insert<CreateGroupOpLowering, AddToGroupOpLowering>(ctx);
patterns.insert<AwaitOpLowering, AwaitAllOpLowering>(ctx, outlinedFunctions);
ConversionTarget target(*ctx);
target.addLegalOp<ConstantOp>();
target.addLegalDialect<LLVM::LLVMDialect>();
target.addIllegalDialect<AsyncDialect>();
target.addDynamicallyLegalOp<FuncOp>(
[&](FuncOp op) { return converter.isSignatureLegal(op.getType()); });
target.addDynamicallyLegalOp<CallOp>(
[&](CallOp op) { return converter.isLegal(op.getResultTypes()); });
if (failed(applyPartialConversion(module, target, std::move(patterns))))
signalPassFailure();
}
} // namespace
std::unique_ptr<OperationPass<ModuleOp>> mlir::createConvertAsyncToLLVMPass() {
return std::make_unique<ConvertAsyncToLLVMPass>();
}