[Mlir-commits] [mlir] [mlir][EmitC]Expand the MemRefToEmitC pass - Lowering `AllocOp` (PR #148257)

[Jaden Angella]

================
@@ -77,6 +78,78 @@ struct ConvertAlloca final : public OpConversionPattern<memref::AllocaOp> {
   }
 };
 
+struct ConvertAlloc final : public OpConversionPattern<memref::AllocOp> {
+  using OpConversionPattern::OpConversionPattern;
+  LogicalResult
+  matchAndRewrite(memref::AllocOp allocOp, OpAdaptor operands,
+                  ConversionPatternRewriter &rewriter) const override {
+    mlir::Location loc = allocOp.getLoc();
+    auto memrefType = allocOp.getType();
+    if (!memrefType.hasStaticShape()) {
+      // TODO: Handle Dynamic shapes in the future. If the size
+      // of the allocation is the result of some function, we could
+      // potentially evaluate the function and use the result in the call to
+      // allocate.
+      return rewriter.notifyMatchFailure(
+          loc, "cannot transform alloc with dynamic shape");
+    }
+
+    Type elementType = memrefType.getElementType();
+    mlir::Value elementTypeLiteral = rewriter.create<emitc::LiteralOp>(
+        loc, mlir::emitc::OpaqueType::get(rewriter.getContext(), "type"),
+        rewriter.getStringAttr(getCTypeName(elementType)));
+    emitc::CallOpaqueOp sizeofElementOp = rewriter.create<emitc::CallOpaqueOp>(
+        loc, mlir::emitc::SizeTType::get(rewriter.getContext()),
+        rewriter.getStringAttr("sizeof"), mlir::ValueRange{elementTypeLiteral});
+    mlir::Value sizeofElement = sizeofElementOp.getResult(0);
+
+    unsigned int elementWidth = elementType.getIntOrFloatBitWidth();
+    mlir::Value numElements;
+    if (elementType.isF32())
+      numElements = rewriter.create<emitc::ConstantOp>(
+          loc, elementType, rewriter.getFloatAttr(elementType, elementWidth));
+    else
+      numElements = rewriter.create<emitc::ConstantOp>(
+          loc, elementType, rewriter.getIntegerAttr(elementType, elementWidth));
+    mlir::Value totalSizeBytes = rewriter.create<emitc::MulOp>(
+        loc, mlir::emitc::SizeTType::get(rewriter.getContext()), sizeofElement,
+        numElements);
+
+    auto mallocCall = rewriter.create<emitc::CallOpaqueOp>(
+        loc,
+        emitc::PointerType::get(
+            rewriter.getContext(),
+            mlir::emitc::OpaqueType::get(rewriter.getContext(), "void")),
+        rewriter.getStringAttr("malloc"), mlir::ValueRange{totalSizeBytes});
+    auto targetPointerType =
+        emitc::PointerType::get(rewriter.getContext(), elementType);
----------------
Jaddyen wrote:

ack, thanks for the pointer!

https://github.com/llvm/llvm-project/pull/148257