[mlir][emitc] Disallow !emitc.opaque pointers

[marbre]

Summary

Fordbids to express pointer via the !emitc.opaque type. Point the user
to use the !emitc.ptr type instead.

[jpienaar]

mlir/lib/Dialect/EmitC/IR/EmitC.cpp

225

Should this only be on the outer most? E.g., this would flag a Small vector<int*, 4> too

[marbre]

Updating D124002: [mlir][emitc] Disallow !emitc.opaque pointers

Only disallow pointers in outer type

[marbre]

mlir/lib/Dialect/EmitC/IR/EmitC.cpp

225

Excellent fetch! Thanks for the hint, I've adopted accordingly and also added a test for a the valid "SmalVector<int*, 4>" case.

[jpienaar]

Thanks!

mlir/lib/Dialect/EmitC/IR/EmitC.cpp

Type emitc::OpaqueType::parse(AsmParser &parser) {
   if (parser.parseLess())
     return Type();
   std::string value;
   SMLoc loc = parser.getCurrentLocation();
   if (parser.parseOptionalString(&value) || value.empty()) {
     parser.emitError(loc) << "expected non empty string in !emitc.opaque type";
     return Type();
   }
+  if (value.find("*") != std::string::npos) {
+    parser.emitError(loc)
+        << "* not allowed in !emitc.opaque type, use !emitc.ptr instead";
+    return Type();
+  }
   if (parser.parseGreater())
     return Type();
   return get(parser.getContext(), value);
 }
 
 void emitc::OpaqueType::print(AsmPrinter &printer) const {
   printer << "<\"";
   llvm::printEscapedString(getValue(), printer.getStream());
   printer << "\">";
 }

mlir/test/Dialect/EmitC/invalid_types.mlir

 // RUN: mlir-opt %s -split-input-file -verify-diagnostics
 
 func @illegal_opaque_type_1() {
     // expected-error @+1 {{expected non empty string in !emitc.opaque type}}
     %1 = "emitc.variable"(){value = "42" : !emitc.opaque<"">} : () -> !emitc.opaque<"mytype">
 }
+
+// -----
+
+func @illegal_opaque_type_2() {
+    // expected-error @+1 {{* not allowed in !emitc.opaque type, use !emitc.ptr instead}}
+    %1 = "emitc.variable"(){value = "nullptr" : !emitc.opaque<"int32_t*">} : () -> !emitc.opaque<"int32_t*">
+}