[PATCH] D74280: [mlir] subview op lowering for target memrefs with const offset

[Tobias Gysi via Phabricator via llvm-commits]

gysit created this revision.
Herald added subscribers: llvm-commits, Joonsoo, liufengdb, aartbik, lucyrfox, mgester, arpith-jacob, nicolasvasilache, antiagainst, shauheen, burmako, jpienaar, rriddle, mehdi_amini.
Herald added a project: LLVM.

The current standard to llvm conversion pass lowers subview ops only if dynamic offsets are provided. This commit extends the lowering with a code path that uses the constant offset of the target memref for the subview op lowering (see Example 3 of the subview op definition for an example) if no dynamic offsets are provided.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D74280

Files:
  mlir/lib/Conversion/StandardToLLVM/ConvertStandardToLLVM.cpp
  mlir/test/Conversion/StandardToLLVM/convert-to-llvmir.mlir


Index: mlir/test/Conversion/StandardToLLVM/convert-to-llvmir.mlir
===================================================================
--- mlir/test/Conversion/StandardToLLVM/convert-to-llvmir.mlir
+++ mlir/test/Conversion/StandardToLLVM/convert-to-llvmir.mlir
@@ -807,6 +807,30 @@
   return
 }
 
+// CHECK-LABEL: func @subview_const_stride_and_offset(
+// CHECK: %[[MEMREFPTR:.*]]: !llvm<{{.*}}>
+func @subview_const_stride_and_offset(%0 : memref<64x4xf32, affine_map<(d0, d1) -> (d0 * 4 + d1)>>) {
+  // CHECK: %[[MEMREF:.*]] = llvm.load %[[MEMREFPTR]] : !llvm<"{ float*, float*, i64, [2 x i64], [2 x i64] }*">
+  // CHECK: %[[DESC:.*]] = llvm.mlir.undef : !llvm<"{ float*, float*, i64, [2 x i64], [2 x i64] }">
+  // CHECK: %[[DESC0:.*]] = llvm.insertvalue %{{.*}}, %[[DESC]][0] : !llvm<"{ float*, float*, i64, [2 x i64], [2 x i64] }">
+  // CHECK: %[[DESC1:.*]] = llvm.insertvalue %{{.*}}, %[[DESC0]][1] : !llvm<"{ float*, float*, i64, [2 x i64], [2 x i64] }">
+  // CHECK: %[[STRIDE0:.*]] = llvm.extractvalue %[[MEMREF]][4, 0] : !llvm<"{ float*, float*, i64, [2 x i64], [2 x i64] }">
+  // CHECK: %[[STRIDE1:.*]] = llvm.extractvalue %[[MEMREF]][4, 1] : !llvm<"{ float*, float*, i64, [2 x i64], [2 x i64] }">
+  // CHECK: %[[CST62:.*]] = llvm.mlir.constant(62 : i64)
+  // CHECK: %[[CST3:.*]] = llvm.mlir.constant(3 : i64)
+  // CHECK: %[[CST8:.*]] = llvm.mlir.constant(8 : index)  
+  // CHECK: %[[DESC2:.*]] = llvm.insertvalue %[[CST8]], %[[DESC1]][2] : !llvm<"{ float*, float*, i64, [2 x i64], [2 x i64] }">
+  // CHECK: %[[DESC3:.*]] = llvm.insertvalue %[[CST3]], %[[DESC2]][3, 1] : !llvm<"{ float*, float*, i64, [2 x i64], [2 x i64] }">
+  // CHECK: %[[CST1:.*]] = llvm.mlir.constant(1 : i64)
+  // CHECK: %[[DESC4:.*]] = llvm.insertvalue %[[CST1]], %[[DESC3]][4, 1] : !llvm<"{ float*, float*, i64, [2 x i64], [2 x i64] }">
+  // CHECK: %[[DESC5:.*]] = llvm.insertvalue %[[CST62]], %[[DESC4]][3, 0] : !llvm<"{ float*, float*, i64, [2 x i64], [2 x i64] }">
+  // CHECK: %[[CST4:.*]] = llvm.mlir.constant(4 : i64)
+  // CHECK: llvm.insertvalue %[[CST4]], %[[DESC5]][4, 0] : !llvm<"{ float*, float*, i64, [2 x i64], [2 x i64] }">
+  %1 = subview %0[][][] :
+    memref<64x4xf32, affine_map<(d0, d1) -> (d0 * 4 + d1)>> to memref<62x3xf32, affine_map<(d0, d1) -> (d0 * 4 + d1 + 8)>>
+  return
+}
+
 // -----
 
 module {
Index: mlir/lib/Conversion/StandardToLLVM/ConvertStandardToLLVM.cpp
===================================================================
--- mlir/lib/Conversion/StandardToLLVM/ConvertStandardToLLVM.cpp
+++ mlir/lib/Conversion/StandardToLLVM/ConvertStandardToLLVM.cpp
@@ -1955,7 +1955,8 @@
     // Currently, only rank > 0 and full or no operands are supported. Fail to
     // convert otherwise.
     unsigned rank = sourceMemRefType.getRank();
-    if (viewMemRefType.getRank() == 0 || (rank != dynamicOffsets.size()) ||
+    if (viewMemRefType.getRank() == 0 ||
+        (!dynamicOffsets.empty() && rank != dynamicOffsets.size()) ||
         (!dynamicSizes.empty() && rank != dynamicSizes.size()) ||
         (!dynamicStrides.empty() && rank != dynamicStrides.size()))
       return matchFailure();
@@ -1966,6 +1967,11 @@
     if (failed(successStrides))
       return matchFailure();
 
+    // Fail to convert if neither a dynamic nor static offset is available.
+    if (dynamicOffsets.empty() &&
+        offset == MemRefType::getDynamicStrideOrOffset())
+      return matchFailure();
+
     // Create the descriptor.
     MemRefDescriptor sourceMemRef(operands.front());
     auto targetMemRef = MemRefDescriptor::undef(rewriter, loc, targetDescTy);
@@ -1999,14 +2005,18 @@
     }
 
     // Offset.
-    Value baseOffset = sourceMemRef.offset(rewriter, loc);
-    for (int i = 0, e = viewMemRefType.getRank(); i < e; ++i) {
-      Value min = dynamicOffsets[i];
-      baseOffset = rewriter.create<LLVM::AddOp>(
-          loc, baseOffset,
-          rewriter.create<LLVM::MulOp>(loc, min, strideValues[i]));
+    if (dynamicOffsets.empty()) {
+      targetMemRef.setConstantOffset(rewriter, loc, offset);
+    } else {
+      Value baseOffset = sourceMemRef.offset(rewriter, loc);
+      for (int i = 0, e = viewMemRefType.getRank(); i < e; ++i) {
+        Value min = dynamicOffsets[i];
+        baseOffset = rewriter.create<LLVM::AddOp>(
+            loc, baseOffset,
+            rewriter.create<LLVM::MulOp>(loc, min, strideValues[i]));
+      }
+      targetMemRef.setOffset(rewriter, loc, baseOffset);
     }
-    targetMemRef.setOffset(rewriter, loc, baseOffset);
 
     // Update sizes and strides.
     for (int i = viewMemRefType.getRank() - 1; i >= 0; --i) {


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