Add generic type attribute mapping infrastructure, use it in GpuToX

Remapping memory spaces is a function often needed in type
conversions, most often when going to LLVM or to/from SPIR-V (a future
commit), and it is possible that such remappings may become more
common in the future as dialects take advantage of the more generic
memory space infrastructure.

Currently, memory space remappings are handled by running a
special-purpose conversion pass before the main conversion that
changes the address space attributes. In this commit, this approach is
replaced by adding a notion of type attribute conversions
TypeConverter, which is then used to convert memory space attributes.

Then, we use this infrastructure throughout the *ToLLVM conversions.
This has the advantage of loosing the requirements on the inputs to
those passes from "all address spaces must be integers" to "all
memory spaces must be convertible to integer spaces", a looser
requirement that reduces the coupling between portions of MLIR.

ON top of that, this change leads to the removal of most of the calls
to getMemorySpaceAsInt(), bringing us closer to removing it.

(A rework of the SPIR-V conversions to use this new system will be in
a folowup commit.)

As a note, one long-term motivation for this change is that I would
eventually like to add an allocaMemorySpace key to MLIR data layouts
and then call getMemRefAddressSpace(allocaMemorySpace) in the
relevant *ToLLVM in order to ensure all alloca()s, whether incoming or
produces during the LLVM lowering, have the correct address space for
a given target.

I expect that the type attribute conversion system may be useful in
other contexts.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D142159

mlir/lib/Conversion/VectorToLLVM/ConvertVectorToLLVM.cpp

@@ -8,6 +8,7 @@
 
 #include "mlir/Conversion/VectorToLLVM/ConvertVectorToLLVM.h"
 
+#include "mlir/Conversion/LLVMCommon/TypeConverter.h"
 #include "mlir/Conversion/LLVMCommon/VectorPattern.h"
 #include "mlir/Dialect/Arith/IR/Arith.h"
 #include "mlir/Dialect/Arith/Utils/Utils.h"
@@ -92,21 +93,25 @@ LogicalResult getMemRefAlignment(LLVMTypeConverter &typeConverter,
 }
 
 // Check if the last stride is non-unit or the memory space is not zero.
-static LogicalResult isMemRefTypeSupported(MemRefType memRefType) {
+static LogicalResult isMemRefTypeSupported(MemRefType memRefType,
+                                           LLVMTypeConverter &converter) {
   int64_t offset;
   SmallVector<int64_t, 4> strides;
   auto successStrides = getStridesAndOffset(memRefType, strides, offset);
-  if (failed(successStrides) || strides.back() != 1 ||
-      memRefType.getMemorySpaceAsInt() != 0)
+  FailureOr<unsigned> addressSpace =
+      converter.getMemRefAddressSpace(memRefType);
+  if (failed(successStrides) || strides.back() != 1 || failed(addressSpace) ||
+      *addressSpace != 0)
     return failure();
   return success();
 }
 
 // Add an index vector component to a base pointer.
 static Value getIndexedPtrs(ConversionPatternRewriter &rewriter, Location loc,
+                            LLVMTypeConverter &typeConverter,
                             MemRefType memRefType, Value llvmMemref, Value base,
                             Value index, uint64_t vLen) {
-  assert(succeeded(isMemRefTypeSupported(memRefType)) &&
+  assert(succeeded(isMemRefTypeSupported(memRefType, typeConverter)) &&
          "unsupported memref type");
   auto pType = MemRefDescriptor(llvmMemref).getElementPtrType();
   auto ptrsType = LLVM::getFixedVectorType(pType, vLen);
@@ -116,8 +121,10 @@ static Value getIndexedPtrs(ConversionPatternRewriter &rewriter, Location loc,
 // Casts a strided element pointer to a vector pointer.  The vector pointer
 // will be in the same address space as the incoming memref type.
 static Value castDataPtr(ConversionPatternRewriter &rewriter, Location loc,
-                         Value ptr, MemRefType memRefType, Type vt) {
-  auto pType = LLVM::LLVMPointerType::get(vt, memRefType.getMemorySpaceAsInt());
+                         Value ptr, MemRefType memRefType, Type vt,
+                         LLVMTypeConverter &converter) {
+  unsigned addressSpace = *converter.getMemRefAddressSpace(memRefType);
+  auto pType = LLVM::LLVMPointerType::get(vt, addressSpace);
   return rewriter.create<LLVM::BitcastOp>(loc, pType, ptr);
 }
 
@@ -245,7 +252,8 @@ public:
                      .template cast<VectorType>();
     Value dataPtr = this->getStridedElementPtr(loc, memRefTy, adaptor.getBase(),
                                                adaptor.getIndices(), rewriter);
-    Value ptr = castDataPtr(rewriter, loc, dataPtr, memRefTy, vtype);
+    Value ptr = castDataPtr(rewriter, loc, dataPtr, memRefTy, vtype,
+                            *this->getTypeConverter());
 
     replaceLoadOrStoreOp(loadOrStoreOp, adaptor, vtype, ptr, align, rewriter);
     return success();
@@ -264,7 +272,7 @@ public:
     MemRefType memRefType = gather.getBaseType().dyn_cast<MemRefType>();
     assert(memRefType && "The base should be bufferized");
 
-    if (failed(isMemRefTypeSupported(memRefType)))
+    if (failed(isMemRefTypeSupported(memRefType, *this->getTypeConverter())))
       return failure();
 
     auto loc = gather->getLoc();
@@ -283,8 +291,8 @@ public:
     if (!llvmNDVectorTy.isa<LLVM::LLVMArrayType>()) {
       auto vType = gather.getVectorType();
       // Resolve address.
-      Value ptrs = getIndexedPtrs(rewriter, loc, memRefType, base, ptr,
-                                  adaptor.getIndexVec(),
+      Value ptrs = getIndexedPtrs(rewriter, loc, *this->getTypeConverter(),
+                                  memRefType, base, ptr, adaptor.getIndexVec(),
                                   /*vLen=*/vType.getDimSize(0));
       // Replace with the gather intrinsic.
       rewriter.replaceOpWithNewOp<LLVM::masked_gather>(
@@ -293,11 +301,14 @@ public:
       return success();
     }
 
-    auto callback = [align, memRefType, base, ptr, loc, &rewriter](
-                        Type llvm1DVectorTy, ValueRange vectorOperands) {
+    LLVMTypeConverter &typeConverter = *this->getTypeConverter();
+    auto callback = [align, memRefType, base, ptr, loc, &rewriter,
+                     &typeConverter](Type llvm1DVectorTy,
+                                     ValueRange vectorOperands) {
       // Resolve address.
       Value ptrs = getIndexedPtrs(
-          rewriter, loc, memRefType, base, ptr, /*index=*/vectorOperands[0],
+          rewriter, loc, typeConverter, memRefType, base, ptr,
+          /*index=*/vectorOperands[0],
           LLVM::getVectorNumElements(llvm1DVectorTy).getFixedValue());
       // Create the gather intrinsic.
       return rewriter.create<LLVM::masked_gather>(
@@ -323,7 +334,7 @@ public:
     auto loc = scatter->getLoc();
     MemRefType memRefType = scatter.getMemRefType();
 
-    if (failed(isMemRefTypeSupported(memRefType)))
+    if (failed(isMemRefTypeSupported(memRefType, *this->getTypeConverter())))
       return failure();
 
     // Resolve alignment.
@@ -335,9 +346,9 @@ public:
     VectorType vType = scatter.getVectorType();
     Value ptr = getStridedElementPtr(loc, memRefType, adaptor.getBase(),
                                      adaptor.getIndices(), rewriter);
-    Value ptrs =
-        getIndexedPtrs(rewriter, loc, memRefType, adaptor.getBase(), ptr,
-                       adaptor.getIndexVec(), /*vLen=*/vType.getDimSize(0));
+    Value ptrs = getIndexedPtrs(
+        rewriter, loc, *this->getTypeConverter(), memRefType, adaptor.getBase(),
+        ptr, adaptor.getIndexVec(), /*vLen=*/vType.getDimSize(0));
 
     // Replace with the scatter intrinsic.
     rewriter.replaceOpWithNewOp<LLVM::masked_scatter>(