[flang-commits] [flang] [flang] Inline hlfir.eoshift during HLFIR intrinsics simplication. (PR #153108)

[Tom Eccles via flang-commits]

================
@@ -1536,63 +1853,143 @@ class CShiftConversion : public mlir::OpRewritePattern<hlfir::CShiftOp> {
         srcIndices.resize(1);
       }
 
-      // Copy first portion of the array:
-      // do i=1,SH
-      //   result(i + (SIZE(ARRAY,DIM) - SH)) = array(i)
-      // end
-      auto genAssign1 = [&](mlir::Location loc, fir::FirOpBuilder &builder,
-                            mlir::ValueRange index,
-                            mlir::ValueRange reductionArgs)
+      // genCopy labda generates the body of a generic copy loop.
+      //   do i=1,COPY_END
+      //     result(i + DEST_OFFSET) = array(i + SOURCE_OFFSET)
+      //   end
+      //
+      // It is parameterized by DEST_OFFSET and SOURCE_OFFSET.
+      mlir::Value dstOffset, srcOffset;
+      auto genCopy = [&](mlir::Location loc, fir::FirOpBuilder &builder,
+                         mlir::ValueRange index, mlir::ValueRange reductionArgs)
           -> llvm::SmallVector<mlir::Value, 0> {
         assert(index.size() == 1 && "expected single loop");
         mlir::Value srcIndex = builder.createConvert(loc, calcType, index[0]);
+        mlir::Value dstIndex = srcIndex;
+        if (srcOffset)
+          srcIndex =
+              mlir::arith::AddIOp::create(builder, loc, srcIndex, srcOffset);
         srcIndices[dimVal - 1] = srcIndex;
         hlfir::Entity srcElementValue =
             hlfir::loadElementAt(loc, builder, srcArray, srcIndices);
-        mlir::Value dstIndex = mlir::arith::AddIOp::create(
-            builder, loc, srcIndex,
-            mlir::arith::SubIOp::create(builder, loc, shiftDimExtent,
-                                        shiftVal));
+        if (dstOffset)
+          dstIndex =
+              mlir::arith::AddIOp::create(builder, loc, dstIndex, dstOffset);
         dstIndices[dimVal - 1] = dstIndex;
         hlfir::Entity dstElement = hlfir::getElementAt(
             loc, builder, hlfir::Entity{resultArray}, dstIndices);
         hlfir::AssignOp::create(builder, loc, srcElementValue, dstElement);
+        // Reset the external parameters' values to make sure
+        // they are properly updated between the labda calls.
----------------
tblah wrote:

```suggestion
        // they are properly updated between the lambda calls.
```

https://github.com/llvm/llvm-project/pull/153108