[flang] Use integer as a place holder type.

The previous placeholder type was basic type with DW_ATE_address
encoding. When variables are added, it started causing assertions in
the llvm debug info generation logic for some types. It has been changed
to an integer type.

Author: abidh

flang/lib/Optimizer/Transforms/DebugTypeGenerator.cpp

@@ -24,11 +24,6 @@ DebugTypeGenerator::DebugTypeGenerator(mlir::ModuleOp m)
   LLVM_DEBUG(llvm::dbgs() << "DITypeAttr generator\n");
 }
 
-static mlir::LLVM::DITypeAttr genPlaceholderType(mlir::MLIRContext *context) {
-  return mlir::LLVM::DIBasicTypeAttr::get(
-      context, llvm::dwarf::DW_TAG_base_type, "void", 32, 1);
-}
-
 static mlir::LLVM::DITypeAttr genBasicType(mlir::MLIRContext *context,
                                            mlir::StringAttr name,
                                            unsigned bitSize,
@@ -37,6 +32,11 @@ static mlir::LLVM::DITypeAttr genBasicType(mlir::MLIRContext *context,
       context, llvm::dwarf::DW_TAG_base_type, name, bitSize, decoding);
 }
 
+static mlir::LLVM::DITypeAttr genPlaceholderType(mlir::MLIRContext *context) {
+  return genBasicType(context, mlir::StringAttr::get(context, "integer"), 32,
+                      llvm::dwarf::DW_ATE_signed);
+}
+
 mlir::LLVM::DITypeAttr
 DebugTypeGenerator::convertType(mlir::Type Ty, mlir::LLVM::DIFileAttr fileAttr,
                                 mlir::LLVM::DIScopeAttr scope,