[Mlir-commits] [mlir] [MLIR][GPU-LLVM] Define `-convert-gpu-to-llvm-spv` pass (PR #90972)

[Jakub Kuderski]

================
@@ -0,0 +1,329 @@
+//===- GPUToLLVMSPV.cpp - Convert GPU operations 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/GPUToLLVMSPV/GPUToLLVMSPVPass.h"
+
+#include "mlir/Conversion/LLVMCommon/ConversionTarget.h"
+#include "mlir/Conversion/LLVMCommon/LoweringOptions.h"
+#include "mlir/Conversion/LLVMCommon/Pattern.h"
+#include "mlir/Conversion/LLVMCommon/TypeConverter.h"
+#include "mlir/Dialect/GPU/IR/GPUDialect.h"
+#include "mlir/Dialect/LLVMIR/LLVMAttrs.h"
+#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
+#include "mlir/Dialect/LLVMIR/LLVMTypes.h"
+#include "mlir/Dialect/SPIRV/IR/SPIRVDialect.h"
+#include "mlir/Dialect/SPIRV/IR/TargetAndABI.h"
+#include "mlir/IR/BuiltinTypes.h"
+#include "mlir/IR/Matchers.h"
+#include "mlir/IR/PatternMatch.h"
+#include "mlir/IR/SymbolTable.h"
+#include "mlir/Pass/Pass.h"
+#include "mlir/Support/LLVM.h"
+#include "mlir/Transforms/DialectConversion.h"
+
+#include "llvm/ADT/TypeSwitch.h"
+#include "llvm/Support/FormatVariadic.h"
+
+namespace mlir {
+#define GEN_PASS_DEF_CONVERTGPUOPSTOLLVMSPVOPS
+#include "mlir/Conversion/Passes.h.inc"
+} // namespace mlir
+
+namespace {
+using namespace mlir;
+
+//===----------------------------------------------------------------------===//
+// Helper Functions
+//===----------------------------------------------------------------------===//
+
+LLVM::LLVMFuncOp lookupOrCreateSPIRVFn(Operation *symbolTable, StringRef name,
+                                       ArrayRef<Type> paramTypes,
+                                       Type resultType) {
+  auto func = dyn_cast_or_null<LLVM::LLVMFuncOp>(
+      SymbolTable::lookupSymbolIn(symbolTable, name));
+  if (!func) {
+    OpBuilder b(symbolTable->getRegion(0));
+    func = b.create<LLVM::LLVMFuncOp>(
+        symbolTable->getLoc(), name,
+        LLVM::LLVMFunctionType::get(resultType, paramTypes));
+    func.setCConv(LLVM::cconv::CConv::SPIR_FUNC);
+  }
+  return func;
+}
+
+LLVM::CallOp createSPIRVBuiltinCall(Location loc,
+                                    ConversionPatternRewriter &rewriter,
+                                    LLVM::LLVMFuncOp func, ValueRange args) {
+  auto call = rewriter.create<LLVM::CallOp>(loc, func, args);
+  call.setCConv(func.getCConv());
+  return call;
+}
+
+//===----------------------------------------------------------------------===//
+// Barriers
+//===----------------------------------------------------------------------===//
+
+/// Replace `gpu.barrier` with an `llvm.call` to `barrier` with
+/// `CLK_LOCAL_MEM_FENCE` argument, indicating work-group memory scope:
+/// ```
+/// // gpu.barrier
+/// %c1 = llvm.mlir.constant(1: i32) : i32
+/// llvm.call spir_funccc @_Z7barrierj(%c1) : (i32) -> ()
+/// ```
+struct GPUBarrierConversion final
+    : public ConvertOpToLLVMPattern<gpu::BarrierOp> {
+  using ConvertOpToLLVMPattern<gpu::BarrierOp>::ConvertOpToLLVMPattern;
+
+  LogicalResult
+  matchAndRewrite(gpu::BarrierOp op, OpAdaptor adaptor,
+                  ConversionPatternRewriter &rewriter) const final {
+    constexpr StringLiteral funcName = "_Z7barrierj";
+
+    Operation *moduleOp = op->getParentWithTrait<OpTrait::SymbolTable>();
+    assert(moduleOp && "Expecting module");
+    Type flagTy = rewriter.getI32Type();
+    Type voidTy = rewriter.getType<LLVM::LLVMVoidType>();
+    LLVM::LLVMFuncOp func =
+        lookupOrCreateSPIRVFn(moduleOp, funcName, flagTy, voidTy);
+
+    // Value used by SPIR-V backend to represent `CLK_LOCAL_MEM_FENCE`.
+    // See `llvm/lib/Target/SPIRV/SPIRVBuiltins.td`.
+    constexpr int64_t localMemFenceFlag = 1;
+    Location loc = op->getLoc();
+    Value flag =
+        rewriter.create<LLVM::ConstantOp>(loc, flagTy, localMemFenceFlag);
+    rewriter.replaceOp(op, createSPIRVBuiltinCall(loc, rewriter, func, flag));
+    return success();
+  }
+};
+
+//===----------------------------------------------------------------------===//
+// SPIR-V Builtins
+//===----------------------------------------------------------------------===//
+
+/// Replace `gpu.*` with an `llvm.call` to the corresponding SPIR-V builtin with
+/// a constant argument for the `dimension` attribute. Return type will depend
+/// on index width option:
+/// ```
+/// // %thread_id_y = gpu.thread_id y
+/// %c1 = llvm.mlir.constant(1: i32) : i32
+/// %0 = llvm.call spir_funccc @_Z12get_local_idj(%c1) : (i32) -> i64
+/// ```
+struct LaunchConfigConversion : public ConvertToLLVMPattern {
+  LaunchConfigConversion(StringRef funcName, StringRef rootOpName,
+                         MLIRContext *context,
+                         const LLVMTypeConverter &typeConverter,
+                         PatternBenefit benefit)
+      : ConvertToLLVMPattern(rootOpName, context, typeConverter, benefit),
+        funcName(funcName) {}
+
+  virtual gpu::Dimension getDimension(Operation *op) const = 0;
+
+  LogicalResult
+  matchAndRewrite(Operation *op, ArrayRef<Value> operands,
+                  ConversionPatternRewriter &rewriter) const final {
+    Operation *moduleOp = op->getParentWithTrait<OpTrait::SymbolTable>();
+    assert(moduleOp && "Expecting module");
+    Type dimTy = rewriter.getI32Type();
+    Type indexTy = getTypeConverter()->getIndexType();
+    LLVM::LLVMFuncOp func =
+        lookupOrCreateSPIRVFn(moduleOp, funcName, dimTy, indexTy);
+
+    Location loc = op->getLoc();
+    gpu::Dimension dim = getDimension(op);
+    Value dimVal = rewriter.create<LLVM::ConstantOp>(loc, dimTy,
+                                                     static_cast<int64_t>(dim));
+    rewriter.replaceOp(op, createSPIRVBuiltinCall(loc, rewriter, func, dimVal));
+    return success();
+  }
+
+  StringRef funcName;
+};
+
+template <typename SourceOp>
+struct LaunchConfigOpConversion final : public LaunchConfigConversion {
+  static StringRef getFuncName();
+
+  explicit LaunchConfigOpConversion(const LLVMTypeConverter &typeConverter,
+                                    PatternBenefit benefit = 1)
+      : LaunchConfigConversion(getFuncName(), SourceOp::getOperationName(),
+                               &typeConverter.getContext(), typeConverter,
+                               benefit) {}
+
+  gpu::Dimension getDimension(Operation *op) const final {
+    return cast<SourceOp>(op).getDimension();
+  }
+};
+
+template <>
+StringRef LaunchConfigOpConversion<gpu::BlockIdOp>::getFuncName() {
+  return "_Z12get_group_idj";
+}
+
+template <>
+StringRef LaunchConfigOpConversion<gpu::GridDimOp>::getFuncName() {
+  return "_Z14get_num_groupsj";
+}
+
+template <>
+StringRef LaunchConfigOpConversion<gpu::BlockDimOp>::getFuncName() {
+  return "_Z14get_local_sizej";
+}
+
+template <>
+StringRef LaunchConfigOpConversion<gpu::ThreadIdOp>::getFuncName() {
+  return "_Z12get_local_idj";
+}
+
+template <>
+StringRef LaunchConfigOpConversion<gpu::GlobalIdOp>::getFuncName() {
+  return "_Z13get_global_idj";
+}
+
+//===----------------------------------------------------------------------===//
+// Shuffles
+//===----------------------------------------------------------------------===//
+
+/// Replace `gpu.shuffle` with an `llvm.call` to the corresponding SPIR-V
+/// builtin for `shuffleResult`, keeping `value` and `offset` arguments, and a
+/// `true` constant for the `valid` result type. Conversion will only take place
+/// if `width` is constant and equal to the `subgroup` pass option:
+/// ```
+/// // %0 = gpu.shuffle idx %value, %offset, %width : f64
+/// %0 = llvm.call spir_funccc @_Z17sub_group_shuffledj(%value, %offset)
+///     : (f64, i32) -> f64
+/// ```
+struct GPUShuffleConversion final
+    : public ConvertOpToLLVMPattern<gpu::ShuffleOp> {
+  using ConvertOpToLLVMPattern<gpu::ShuffleOp>::ConvertOpToLLVMPattern;
----------------
kuhar wrote:

```suggestion
  using ConvertOpToLLVMPattern::ConvertOpToLLVMPattern;
```

https://github.com/llvm/llvm-project/pull/90972