[clang] [OpenACC][CIR] Add lowering for 'copy' array indexes (PR #140971)

[Andy Kaylor via cfe-commits]

================
@@ -184,37 +189,94 @@ class OpenACCClauseCIREmitter final
     mlir::Location beginLoc;
     mlir::Value varValue;
     llvm::StringRef name;
+    llvm::SmallVector<mlir::Value> bounds;
   };
 
+  mlir::Value createBound(mlir::Location boundLoc, mlir::Value lowerBound,
+                          mlir::Value upperBound, mlir::Value extent) {
+    // Arrays always have a start-idx of 0.
+    mlir::Value startIdx = createConstantInt(boundLoc, 64, 0);
+    // TODO: OpenACC: It isn't clear that stride would ever be anything other
+    // than '1'?  We emit the type of the reference 'correctly' as far as I
+    // know, so it should just be 1 element each time. We could perhaps use
+    // the 'inBytes' variant here, but it isn't clear what value that gets us.
+    // We might need to revisit this once we try to opt this and see what is
+    // going to happen.
+    mlir::Value stride = createConstantInt(boundLoc, 64, 1);
+
+    auto bound = builder.create<mlir::acc::DataBoundsOp>(boundLoc, lowerBound,
+                                                         upperBound);
+    bound.getStartIdxMutable().assign(startIdx);
+    if (extent)
+      bound.getExtentMutable().assign(extent);
+    bound.getStrideMutable().assign(stride);
+
+    return bound;
+  }
+
   // A helper function that gets the information from an operand to a data
   // clause, so that it can be used to emit the data operations.
-  inline DataOperandInfo getDataOperandInfo(OpenACCDirectiveKind dk,
-                                            const Expr *e) {
+  DataOperandInfo getDataOperandInfo(OpenACCDirectiveKind dk, const Expr *e) {
     // TODO: OpenACC: Cache was different enough as to need a separate
     // `ActOnCacheVar`, so we are going to need to do some investigations here
     // when it comes to implement this for cache.
     if (dk == OpenACCDirectiveKind::Cache) {
       cgf.cgm.errorNYI(e->getSourceRange(),
                        "OpenACC data operand for 'cache' directive");
-      return {cgf.cgm.getLoc(e->getBeginLoc()), {}, {}};
+      return {cgf.cgm.getLoc(e->getBeginLoc()), {}, {}, {}};
     }
 
     const Expr *curVarExpr = e->IgnoreParenImpCasts();
 
     mlir::Location exprLoc = cgf.cgm.getLoc(curVarExpr->getBeginLoc());
+    llvm::SmallVector<mlir::Value> bounds;
+
+    // Assemble the list of bounds.
+    while (isa<ArraySectionExpr, ArraySubscriptExpr>(curVarExpr)) {
+      mlir::Location boundLoc = cgf.cgm.getLoc(curVarExpr->getBeginLoc());
+      mlir::Value lowerBound;
+      mlir::Value upperBound;
+      mlir::Value extent;
+
+      if (const auto *section = dyn_cast<ArraySectionExpr>(curVarExpr)) {
+        if (const Expr *lb = section->getLowerBound())
+          lowerBound = emitIntExpr(lb);
+        else
+          lowerBound = createConstantInt(boundLoc, 64, 0);
+
+        if (const Expr *len = section->getLength()) {
+          extent = emitIntExpr(len);
+        } else {
+          QualType baseTy = ArraySectionExpr::getBaseOriginalType(
+              section->getBase()->IgnoreParenImpCasts());
+          // We know this is the case as implicit lengths are only allowed for
+          // array types with a constant size, or a dependent size.  AND since
+          // we are codegen we know we're not dependent.
+          auto *arrayTy = cgf.getContext().getAsConstantArrayType(baseTy);
+          // Rather than trying to calculate the extent based on the
+          // lower-bound, we can just emit this as an upper bound.
+          upperBound =
+              createConstantInt(boundLoc, 64, arrayTy->getLimitedSize() - 1);
+        }
 
-    // TODO: OpenACC: Assemble the list of bounds.
-    if (isa<ArraySectionExpr, ArraySubscriptExpr>(curVarExpr)) {
-      cgf.cgm.errorNYI(curVarExpr->getSourceRange(),
-                       "OpenACC data clause array subscript/section");
-      return {exprLoc, {}, {}};
+        curVarExpr = section->getBase()->IgnoreParenImpCasts();
+      } else {
+        const auto *subscript = dyn_cast<ArraySubscriptExpr>(curVarExpr);
----------------
andykaylor wrote:

```suggestion
        const auto *subscript = cast<ArraySubscriptExpr>(curVarExpr);
```

https://github.com/llvm/llvm-project/pull/140971