[mlir][spirv] Add conversion pass to rewrite splat constant composite…

mlir/include/mlir/Dialect/SPIRV/Transforms/Passes.td

@@ -77,4 +77,11 @@ def SPIRVWebGPUPreparePass : Pass<"spirv-webgpu-prepare", "spirv::ModuleOp"> {
                 "and replacing with supported ones";
 }
 
+def SPIRVReplicatedConstantCompositePass
+    : Pass<"spirv-convert-to-replicated-const-composite", "spirv::ModuleOp"> {
+  let summary = "Convert splat composite constants and spec constants to"
+                "corresponding replicated constant composite ops defined by"
+                "SPV_EXT_replicated_composites";
+}
+
 #endif // MLIR_DIALECT_SPIRV_TRANSFORMS_PASSES

mlir/lib/Dialect/SPIRV/Transforms/CMakeLists.txt

@@ -1,5 +1,6 @@
 set(LLVM_OPTIONAL_SOURCES
   CanonicalizeGLPass.cpp
+  ConversionToReplicatedConstantCompositePass.cpp
   DecorateCompositeTypeLayoutPass.cpp
   LowerABIAttributesPass.cpp
   RewriteInsertsPass.cpp
@@ -30,6 +31,7 @@ add_mlir_dialect_library(MLIRSPIRVConversion
 
 add_mlir_dialect_library(MLIRSPIRVTransforms
   CanonicalizeGLPass.cpp
+  ConversionToReplicatedConstantCompositePass.cpp
   DecorateCompositeTypeLayoutPass.cpp
   LowerABIAttributesPass.cpp
   RewriteInsertsPass.cpp

mlir/lib/Dialect/SPIRV/Transforms/ConversionToReplicatedConstantCompositePass.cpp

@@ -0,0 +1,137 @@
+//===- ConversionToReplicatedConstantCompositePass.cpp --------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements a pass to convert a splat composite spirv.Constant and
+// spirv.SpecConstantComposite to spirv.EXT.ConstantCompositeReplicate and
+// spirv.EXT.SpecConstantCompositeReplicate respectively.
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Dialect/SPIRV/IR/SPIRVOps.h"
+#include "mlir/Dialect/SPIRV/Transforms/Passes.h"
+#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
+
+namespace mlir {
+namespace spirv {
+#define GEN_PASS_DEF_SPIRVREPLICATEDCONSTANTCOMPOSITEPASS
+#include "mlir/Dialect/SPIRV/Transforms/Passes.h.inc"
+} // namespace spirv
+} // namespace mlir
+
+using namespace mlir;
+
+namespace {
+
+Attribute getSplatAttribute(Attribute valueAttr, uint32_t &splatCount) {
+  Attribute attr;
+  if (auto denseAttr = dyn_cast<DenseElementsAttr>(valueAttr)) {
+    if (denseAttr.isSplat()) {
+      attr = denseAttr.getSplatValue<Attribute>();
+      splatCount = denseAttr.size();
+    }
+  } else if (auto arrayAttr = dyn_cast<ArrayAttr>(valueAttr)) {
+    if (std::adjacent_find(arrayAttr.begin(), arrayAttr.end(),
+                           std::not_equal_to<>()) == arrayAttr.end()) {
+      attr = arrayAttr[0];
+      splatCount = arrayAttr.size();
+    }
+  }
+
+  if (attr) {
+    if (auto typedAttr = dyn_cast<TypedAttr>(attr)) {
+      if (isa<spirv::CompositeType>(typedAttr.getType()))
+        if (Attribute newAttr = getSplatAttribute(attr, splatCount))
+          attr = newAttr;
+    } else if (isa<ArrayAttr>(attr)) {
+      if (Attribute newAttr = getSplatAttribute(attr, splatCount))
+        attr = newAttr;
+    }
+  }
+
+  return attr;
+}
+
+} // namespace
+
+namespace {
+class ConversionToReplicatedConstantCompositePass
+    : public spirv::impl::SPIRVReplicatedConstantCompositePassBase<
+          ConversionToReplicatedConstantCompositePass> {
+public:
+  void runOnOperation() override;
+};
+
+class ConstantOpConversion : public OpRewritePattern<spirv::ConstantOp> {
+  using OpRewritePattern<spirv::ConstantOp>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(spirv::ConstantOp op,
+                                PatternRewriter &rewriter) const override {
+    auto compositeType = dyn_cast_or_null<spirv::CompositeType>(op.getType());
+    if (!compositeType)
+      return rewriter.notifyMatchFailure(op, "not a composite constant");
+
+    uint32_t splatCount = 0;
+    Attribute splatAttr = getSplatAttribute(op.getValue(), splatCount);
+    if (!splatAttr)
+      return rewriter.notifyMatchFailure(op, "composite is not splat");
+
+    if (splatCount == 1)
+      return rewriter.notifyMatchFailure(op,
+                                         "composite has only one constituent");
+
+    rewriter.replaceOpWithNewOp<spirv::EXTConstantCompositeReplicateOp>(
+        op, op.getType(), splatAttr);
+
+    return success();
+  }
+};
+
+class SpecConstantCompositeOpConversion
+    : public OpRewritePattern<spirv::SpecConstantCompositeOp> {
+  using OpRewritePattern<spirv::SpecConstantCompositeOp>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(spirv::SpecConstantCompositeOp op,
+                                PatternRewriter &rewriter) const override {
+    auto compositeType = dyn_cast_or_null<spirv::CompositeType>(op.getType());
+    if (!compositeType)
+      return rewriter.notifyMatchFailure(op, "not a composite constant");
+
+    ArrayAttr constituents = op.getConstituents();
+    if (constituents.size() == 1)
+      return rewriter.notifyMatchFailure(op,
+                                         "composite has only one consituent");
+
+    if (!(std::adjacent_find(constituents.begin(), constituents.end(),
+                             std::not_equal_to<>()) == constituents.end()))
+      return rewriter.notifyMatchFailure(op, "composite is not splat");
+
+    auto splatConstituent =
+        dyn_cast<FlatSymbolRefAttr>(op.getConstituents()[0]);
+    if (!splatConstituent)
+      return rewriter.notifyMatchFailure(
+          op, "expected flat symbol reference for splat constituent");
+
+    rewriter.replaceOpWithNewOp<spirv::EXTSpecConstantCompositeReplicateOp>(
+        op, TypeAttr::get(op.getType()), op.getSymNameAttr(), splatConstituent);
+
+    return success();
+  }
+};
+
+void ConversionToReplicatedConstantCompositePass::runOnOperation() {
+  MLIRContext *context = &getContext();
+  RewritePatternSet patterns(context);
+  patterns.add<ConstantOpConversion>(context);
+  patterns.add<SpecConstantCompositeOpConversion>(context);
+
+  if (failed(applyPatternsGreedily(getOperation(), std::move(patterns)))) {
+    signalPassFailure();
+  }
+}
+
+} // namespace