gcc/rust/expand/rust-macro-builtins-asm.cc

// Copyright (C) 2020-2025 Free Software Foundation, Inc.

// This file is part of GCC.

// GCC is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 3, or (at your option) any later
// version.

// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.

// You should have received a copy of the GNU General Public License
// along with GCC; see the file COPYING3.  If not see
// <http://www.gnu.org/licenses/>.

#include "expected.h"
#include "rust-macro-builtins-asm.h"
#include "rust-ast-fragment.h"
#include "rust-ast.h"
#include "rust-fmt.h"
#include "rust-stmt.h"
#include "rust-parse.h"

namespace Rust {
std::set<std::string> potentially_nonpromoted_keywords
  = {"in", "out", "lateout", "inout", "inlateout", "const", "sym", "label"};

// Helper function strips the beginning and ending double quotes from a
// string.
std::string
strip_double_quotes (const std::string &str)
{
  std::string result = str;

  rust_assert (!str.empty ());

  rust_assert (str.front () == '\"');
  rust_assert (str.back () == '\"');

  // we have to special case empty strings which just contain a set of quotes
  // so, if the string is "\"\"", just return ""
  if (result.size () == 2)
    return "";

  rust_assert (result.size () >= 3);

  result.erase (0, 1);
  result.erase (result.size () - 1, 1);

  return result;
}

tl::expected<InlineAsmContext, InlineAsmParseError>
parse_clobber_abi (InlineAsmContext inline_asm_ctx)
{
  // clobber_abi := "clobber_abi(" <abi> *("," <abi>) [","] ")"
  // PARSE EVERYTHING COMMITTEDLY IN THIS FUNCTION, WE CONFIRMED VIA clobber_abi
  // identifier keyword
  auto &parser = inline_asm_ctx.parser;
  auto last_token_id = inline_asm_ctx.last_token_id;
  auto &inline_asm = inline_asm_ctx.inline_asm;
  auto token = parser.peek_current_token ();
  if (!parser.skip_token (LEFT_PAREN))
    {
      token = parser.peek_current_token ();

      // TODO: Error reporting shifted to the left 1 character, I'm not sure
      // why.
      if (token->get_id () == last_token_id)
	{
	  rust_error_at (token->get_locus (),
			 "expected %<(%>, found end of macro arguments");
	  return tl::unexpected<InlineAsmParseError> (COMMITTED);
	}
      else
	{
	  rust_error_at (token->get_locus (), "expected %<(%>, found %qs",
			 token->get_token_description ());
	}
      return tl::unexpected<InlineAsmParseError> (COMMITTED);
    }

  if (parser.skip_token (RIGHT_PAREN))
    {
      rust_error_at (
	parser.peek_current_token ()->get_locus (),
	"at least one abi must be provided as an argument to %<clobber_abi%>");
      return tl::unexpected<InlineAsmParseError> (COMMITTED);
    }

  std::vector<AST::TupleClobber> new_abis;

  token = parser.peek_current_token ();

  while (token->get_id () != last_token_id && token->get_id () != RIGHT_PAREN)
    {
      // Check if it is a string literal or not, codename: <ABI> in ABNF
      if (token->get_id () == STRING_LITERAL)
	{
	  // TODO: Caring for span in here.
	  new_abis.push_back ({token->as_string (), token->get_locus ()});
	}
      else
	{
	  // TODO: We encountered something that is not string literal, which
	  // should be illegal, please emit the correct error
	  // https://github.com/rust-lang/rust/blob/b92758a9aef1cef7b79e2b72c3d8ba113e547f89/compiler/rustc_builtin_macros/src/asm.rs#L387
	  rust_unreachable ();
	}

      if (parser.skip_token (RIGHT_PAREN))
	{
	  break;
	}

      if (!parser.skip_token (COMMA))
	{
	  // TODO: If the skip of comma is unsuccessful, which should be
	  // illegal, pleaes emit the correct error.
	  rust_unreachable ();
	  return tl::unexpected<InlineAsmParseError> (COMMITTED);
	}

      token = parser.peek_current_token ();
    }

  // Done processing the local clobber abis, push that to the main Args in
  // argument

  for (auto abi : new_abis)
    {
      inline_asm.clobber_abi.push_back (abi);
    }

  return inline_asm_ctx;
}

tl::optional<AST::InlineAsmRegOrRegClass>
parse_reg (InlineAsmContext &inline_asm_ctx)
{
  using RegType = AST::InlineAsmRegOrRegClass::Type;
  auto &parser = inline_asm_ctx.parser;

  if (!parser.skip_token (LEFT_PAREN))
    {
      // TODO: we expect a left parenthesis here, please return the correct
      // error.
      rust_unreachable ();
      return tl::nullopt;
    }

  // after successful left parenthesis parsing, we should return ast of
  // InlineAsmRegOrRegClass of reg or reg class
  auto token = parser.peek_current_token ();
  AST::InlineAsmRegOrRegClass reg_class;
  if (parser.skip_token (IDENTIFIER))
    {
      // construct a InlineAsmRegOrRegClass
      reg_class.type = RegType::RegClass;
      reg_class.reg_class.Symbol = token->as_string ();
    }
  else if (parser.skip_token (STRING_LITERAL))
    {
      // TODO: there is STRING_LITERAL, and BYTE_STRING_LITERAL, should we check
      // for both?

      // construct a InlineAsmRegOrRegClass
      // parse_format_string
      reg_class.type = RegType::Reg;
      inline_asm_ctx.is_explicit = true;
      reg_class.reg_class.Symbol = token->as_string ();
    }
  else
    {
      // TODO: This should emit error
      //  return
      //  Err(p.dcx().create_err(errors::ExpectedRegisterClassOrExplicitRegister
      //  {
      //           span: p.token.span,
      //       }));
      rust_unreachable ();
    }
  if (!parser.skip_token (RIGHT_PAREN))
    {
      // TODO: we expect a left parenthesis here, please return the correct
      // error.
      rust_unreachable ();
      return tl::nullopt;
    }

  return reg_class;
}

// From rustc
tl::expected<InlineAsmContext, InlineAsmParseError>
parse_reg_operand (InlineAsmContext inline_asm_ctx)
{
  // let name = if p.token.is_ident() && p.look_ahead(1, |t| *t == token::Eq) {
  //           let (ident, _) = p.token.ident().unwrap();
  //           p.bump();
  //           p.expect(&token::Eq)?;
  //           allow_templates = false;
  //           Some(ident.name)
  //       } else {
  //           None
  //       };
  auto &parser = inline_asm_ctx.parser;
  auto token = parser.peek_current_token ();
  auto iden_token = parser.peek_current_token ();

  tl::optional<std::string> name = tl::nullopt;
  if (check_identifier (parser, ""))
    {
      auto equal_token = parser.peek_current_token ();

      if (parser.skip_token (EQUAL))
	{
	  name = token->as_string ();
	}
      else
	{
	  rust_error_at (token->get_locus (),
			 "expected operand, %s, options, or "
			 "additional template string",
			 "clobber_abi");
	  return tl::unexpected<InlineAsmParseError> (COMMITTED);
	}
    }

  int slot = inline_asm_ctx.inline_asm.operands.size ();

  // Here is all parse_reg_operand functions we're using in a for loop
  auto parse_funcs = {parse_reg_operand_in,	   parse_reg_operand_out,
		      parse_reg_operand_lateout,   parse_reg_operand_inout,
		      parse_reg_operand_const,	   parse_reg_operand_sym,
		      parse_reg_operand_unexpected};

  // Loop over and execute the parsing functions, if the parser successfullly
  // parses or if the parser fails to parse while it has committed to a token,
  // we propogate the result.
  tl::expected<InlineAsmContext, InlineAsmParseError> parsing_operand (
    inline_asm_ctx);
  for (auto &parse_func : parse_funcs)
    {
      auto result = parsing_operand.and_then (parse_func);

      // Per rust's asm.rs's structure
      // After we've parse successfully, we break out and do a local validation
      // of named, positional & explicit register operands

      if (result.has_value ())
	{
	  inline_asm_ctx = *result;
	  break;
	}
      else if (result.error () == COMMITTED)
	{
	  if (parse_func == parse_reg_operand_unexpected)
	    return inline_asm_ctx;
	  else
	    return result;
	}
    }

  auto &inline_asm = inline_asm_ctx.inline_asm;

  token = inline_asm_ctx.parser.peek_current_token ();
  rust_debug_loc (token->get_locus (), "Here\n");
  if (inline_asm_ctx.is_explicit)
    {
      if (name != tl::nullopt)
	{
	  rust_error_at (token->get_locus (),
			 "explicit register arguments cannot have names");
	  return tl::unexpected<InlineAsmParseError> (COMMITTED);
	}
      inline_asm.reg_args.insert (slot);
    }
  else if (name != tl::nullopt)
    {
      if (inline_asm.named_args.find (name.value ())
	  != inline_asm.named_args.end ())
	{
	  rust_error_at (token->get_locus (), "duplicate argument named %qs",
			 name.value ().c_str ());
	  return tl::unexpected<InlineAsmParseError> (COMMITTED);
	}
      inline_asm.named_args[name.value ()] = slot;
    }
  else
    {
      if (!inline_asm.named_args.empty () || !inline_asm.reg_args.empty ())
	{
	  // positional arguments cannot follow named arguments or explicit
	  // register arguments
	  rust_error_at (token->get_locus (),
			 "positional arguments cannot follow named arguments "
			 "or explicit register arguments");
	  return tl::unexpected<InlineAsmParseError> (COMMITTED);
	}
    }

  return inline_asm_ctx;
}

tl::expected<InlineAsmContext, InlineAsmParseError>
parse_reg_operand_in (InlineAsmContext inline_asm_ctx)
{
  // For the keyword IN, currently we count it as a seperate keyword called
  // Rust::IN search for #define RS_TOKEN_LIST in code base.
  auto &parser = inline_asm_ctx.parser;
  location_t locus = parser.peek_current_token ()->get_locus ();
  if (!inline_asm_ctx.is_global_asm () && parser.skip_token (IN))
    {
      auto reg = parse_reg (inline_asm_ctx);

      if (parser.skip_token (UNDERSCORE))
	{
	  // We are sure to be failing a test here, based on asm.rs
	  // https://github.com/rust-lang/rust/blob/a330e49593ee890f9197727a3a558b6e6b37f843/compiler/rustc_builtin_macros/src/asm.rs#L112
	  rust_unreachable ();
	  // return tl::unexpected<InlineAsmParseError> (COMMITTED);
	}

      auto expr = parser.parse_expr ();

      // TODO: When we've succesfully parse an expr, remember to clone_expr()
      // instead of nullptr
      AST::InlineAsmOperand::In in (reg, std::move (expr));
      inline_asm_ctx.inline_asm.operands.emplace_back (in, locus);
      return inline_asm_ctx;
    }
  return tl::unexpected<InlineAsmParseError> (NONCOMMITED);
}

tl::expected<InlineAsmContext, InlineAsmParseError>
parse_reg_operand_out (InlineAsmContext inline_asm_ctx)
{
  auto &parser = inline_asm_ctx.parser;
  location_t locus = parser.peek_current_token ()->get_locus ();
  if (!inline_asm_ctx.is_global_asm () && check_identifier (parser, "out"))
    {
      auto reg = parse_reg (inline_asm_ctx);
      std::unique_ptr<AST::Expr> expr = parser.parse_expr ();

      rust_assert (expr != nullptr);

      /*auto expr_ptr =
	 std::make_unique<AST::Expr>(AST::LiteralExpr(Literal))*/

      // TODO: When we've succesfully parse an expr, remember to clone_expr()
      // instead of nullptr
      AST::InlineAsmOperand::Out out (reg, false, std::move (expr));

      inline_asm_ctx.inline_asm.operands.emplace_back (out, locus);

      return inline_asm_ctx;
    }

  return tl::unexpected<InlineAsmParseError> (NONCOMMITED);
}

tl::expected<InlineAsmContext, InlineAsmParseError>
parse_reg_operand_lateout (InlineAsmContext inline_asm_ctx)
{
  auto &parser = inline_asm_ctx.parser;
  auto token = parser.peek_current_token ();
  if (!inline_asm_ctx.is_global_asm () && check_identifier (parser, "lateout"))
    {
      rust_error_at (token->get_locus (),
		     "The lateout feature is not implemented");
      rust_unreachable ();
      return tl::unexpected<InlineAsmParseError> (COMMITTED);
    }

  return tl::unexpected<InlineAsmParseError> (NONCOMMITED);
}

tl::expected<InlineAsmContext, InlineAsmParseError>
parse_reg_operand_inout (InlineAsmContext inline_asm_ctx)
{
  auto &parser = inline_asm_ctx.parser;
  auto token = parser.peek_current_token ();
  location_t locus = token->get_locus ();

  if (!inline_asm_ctx.is_global_asm () && check_identifier (parser, "inout"))
    {
      auto reg = parse_reg (inline_asm_ctx);

      if (parser.skip_token (UNDERSCORE))
	{
	  // We are sure to be failing a test here, based on asm.rs
	  // https://github.com/rust-lang/rust/blob/a330e49593ee890f9197727a3a558b6e6b37f843/compiler/rustc_builtin_macros/src/asm.rs#L112
	  rust_error_at (token->get_locus (),
			 "The lateout feature is not implemented");
	  rust_unreachable ();
	  return tl::unexpected<InlineAsmParseError> (COMMITTED);
	}

      // TODO: Is error propogation our top priority, the ? in rust's asm.rs is
      // doing a lot of work.
      std::unique_ptr<AST::Expr> in_expr = parser.parse_expr ();
      rust_assert (in_expr != nullptr);

      std::unique_ptr<AST::Expr> out_expr;

      if (parser.skip_token (MATCH_ARROW))
	{
	  if (!parser.skip_token (UNDERSCORE))
	    {
	      // auto result = parse_format_string (inline_asm_ctx);

	      out_expr = parser.parse_expr ();

	      AST::InlineAsmOperand::SplitInOut splitinout (
		reg, false, std::move (in_expr), std::move (out_expr));

	      inline_asm_ctx.inline_asm.operands.emplace_back (splitinout,
							       locus);

	      return inline_asm_ctx;
	    }

	  rust_unreachable ();

	  // TODO: Rembmer to pass in clone_expr() instead of nullptr
	  // https://github.com/rust-lang/rust/blob/a3167859f2fd8ff2241295469876a2b687280bdc/compiler/rustc_builtin_macros/src/asm.rs#L135
	  // RUST VERSION: ast::InlineAsmOperand::SplitInOut { reg, in_expr:
	  // expr, out_expr, late: false }
	  //	  struct AST::InlineAsmOperand::SplitInOut split_in_out (reg,
	  // false, nullptr,
	  // nullptr);
	  // inline_asm_ctx.inline_asm.operands.push_back (split_in_out);

	  return inline_asm_ctx;
	}
      else
	{
	  AST::InlineAsmOperand::InOut inout (reg, false, std::move (in_expr));
	  inline_asm_ctx.inline_asm.operands.emplace_back (inout, locus);
	  // https://github.com/rust-lang/rust/blob/a3167859f2fd8ff2241295469876a2b687280bdc/compiler/rustc_builtin_macros/src/asm.rs#L137
	  // RUST VERSION: ast::InlineAsmOperand::InOut { reg, expr, late: false
	  // }
	  //	  struct AST::InlineAsmOperand::InOut inout (reg, false,
	  // nullptr);
	  //	  inline_asm_ctx.inline_asm.operands.push_back (inout);
	  return inline_asm_ctx;
	}
    }

  return tl::unexpected<InlineAsmParseError> (NONCOMMITED);
}

tl::expected<InlineAsmContext, InlineAsmParseError>
parse_reg_operand_const (InlineAsmContext inline_asm_ctx)
{
  auto &parser = inline_asm_ctx.parser;
  if (parser.peek_current_token ()->get_id () == CONST)
    {
      // TODO: Please handle const with parse_expr instead.
      auto anon_const = parse_format_string (inline_asm_ctx);
      rust_unreachable ();
      return tl::unexpected<InlineAsmParseError> (COMMITTED);
    }

  return tl::unexpected<InlineAsmParseError> (NONCOMMITED);
}

tl::expected<InlineAsmContext, InlineAsmParseError>
parse_reg_operand_sym (InlineAsmContext inline_asm_ctx)
{
  auto &parser = inline_asm_ctx.parser;

  if (check_identifier (parser, "sym"))
    {
      // TODO: Please handle sym, which needs ExprKind::Path in Rust's asm.rs
      rust_unreachable ();
      return tl::unexpected<InlineAsmParseError> (COMMITTED);
    }
  return tl::unexpected<InlineAsmParseError> (NONCOMMITED);
}

tl::expected<InlineAsmContext, InlineAsmParseError>
parse_reg_operand_unexpected (InlineAsmContext inline_asm_ctx)
{
  auto token = inline_asm_ctx.parser.peek_current_token ();
  // TODO: It is  weird that we can't seem to match any identifier,
  // something must be wrong. consult compiler code in asm.rs or rust online
  // compiler.
  // rust_unreachable ();

  // rust_error_at (token->get_locus (), "ERROR RIGHT HERE");
  return tl::unexpected<InlineAsmParseError> (COMMITTED);
}

void
check_and_set (InlineAsmContext &inline_asm_ctx, AST::InlineAsm::Option option)
{
  auto &parser = inline_asm_ctx.parser;
  auto &inline_asm = inline_asm_ctx.inline_asm;
  if (inline_asm.options.count (option) != 0)
    {
      // TODO: report an error of duplication
      rust_error_at (parser.peek_current_token ()->get_locus (),
		     "the %qs option was already provided",
		     AST::InlineAsm::option_to_string (option).c_str ());
      return;
    }
  else
    {
      inline_asm.options.insert (option);
    }
}
tl::expected<InlineAsmContext, InlineAsmParseError>
parse_options (InlineAsmContext &inline_asm_ctx)
{
  auto &parser = inline_asm_ctx.parser;
  bool is_global_asm = inline_asm_ctx.inline_asm.is_global_asm;
  // Parse everything commitedly
  if (!parser.skip_token (LEFT_PAREN))
    {
      auto local_token = parser.peek_current_token ();
      rust_error_at (local_token->get_locus (), "expected %qs, found %qs", "(",
		     local_token->as_string ().c_str ());
      return tl::unexpected<InlineAsmParseError> (COMMITTED);
    }

  auto token = parser.peek_current_token ();
  while (!parser.skip_token (RIGHT_PAREN))
    {
      if (!is_global_asm && check_identifier (parser, "pure"))
	{
	  check_and_set (inline_asm_ctx, AST::InlineAsm::Option::PURE);
	}
      else if (!is_global_asm && check_identifier (parser, "nomem"))
	{
	  check_and_set (inline_asm_ctx, AST::InlineAsm::Option::NOMEM);
	}
      else if (!is_global_asm && check_identifier (parser, "readonly"))
	{
	  check_and_set (inline_asm_ctx, AST::InlineAsm::Option::READONLY);
	}
      else if (!is_global_asm && check_identifier (parser, "preserves_flags"))
	{
	  check_and_set (inline_asm_ctx,
			 AST::InlineAsm::Option::PRESERVES_FLAGS);
	}
      else if (!is_global_asm && check_identifier (parser, "noreturn"))
	{
	  check_and_set (inline_asm_ctx, AST::InlineAsm::Option::NORETURN);
	}
      else if (!is_global_asm && check_identifier (parser, "nostack"))
	{
	  check_and_set (inline_asm_ctx, AST::InlineAsm::Option::NOSTACK);
	}
      else if (!is_global_asm && check_identifier (parser, "may_unwind"))
	{
	  check_and_set (inline_asm_ctx, AST::InlineAsm::Option::MAY_UNWIND);
	}
      else if (check_identifier (parser, "att_syntax"))
	{
	  check_and_set (inline_asm_ctx, AST::InlineAsm::Option::ATT_SYNTAX);
	}
      else if (check_identifier (parser, "raw"))
	{
	  check_and_set (inline_asm_ctx, AST::InlineAsm::Option::RAW);
	}
      else
	{
	  rust_error_at (token->get_locus (),
			 "expected one of %qs, %qs, %qs, %qs, %qs, %qs, %qs, "
			 "%qs, %qs, or %qs, found %qs",
			 ")", "att_syntax", "may_unwind", "nomem", "noreturn",
			 "nostack", "preserves_flags", "pure", "raw",
			 "readonly", token->as_string ().c_str ());
	  return tl::unexpected<InlineAsmParseError> (COMMITTED);
	}
      if (parser.skip_token (RIGHT_PAREN))
	{
	  break;
	}

      // Parse comma as optional
      if (parser.skip_token (COMMA))
	continue;
      else
	{
	  rust_unreachable ();
	  token = parser.peek_current_token ();
	  return tl::unexpected<InlineAsmParseError> (COMMITTED);
	}
    }

  // TODO: Per rust asm.rs regarding options_spans
  // I'm guessing this has to do with some error reporting.
  // let new_span = span_start.to(p.prev_token.span);
  // args.options_spans.push(new_span);

  return inline_asm_ctx;
}

bool
check_identifier (Parser<MacroInvocLexer> &p, std::string ident)
{
  auto token = p.peek_current_token ();

  if (token->get_id () == IDENTIFIER)
    {
      auto str = token->as_string ();

      // For non-promoted keywords, we need to also check for them.

      if (str == ident)
	{
	  p.skip_token ();
	  return true;
	}
      if (ident == "")
	{
	  if (potentially_nonpromoted_keywords.find (str)
	      == potentially_nonpromoted_keywords.end ())
	    {
	      p.skip_token ();
	      return true;
	    }
	  return false;
	}
    }

  return false;
}

tl::optional<std::string>
parse_format_string (InlineAsmContext &inline_asm_ctx)
{
  auto &parser = inline_asm_ctx.parser;
  auto last_token_id = inline_asm_ctx.last_token_id;
  auto token = parser.peek_current_token ();

  if (token->get_id () != last_token_id && token->get_id () == STRING_LITERAL)
    {
      // very nice, we got a supposedly formatted string.
      parser.skip_token ();
      return token->as_string ();
    }
  else
    {
      return tl::nullopt;
    }
}

tl::optional<AST::Fragment>
MacroBuiltin::asm_handler (location_t invoc_locus, AST::MacroInvocData &invoc,
			   AST::InvocKind semicolon, AST::AsmKind is_global_asm)
{
  return parse_asm (invoc_locus, invoc, semicolon, is_global_asm);
}

tl::optional<AST::Fragment>
MacroBuiltin::llvm_asm_handler (location_t invoc_locus,
				AST::MacroInvocData &invoc,
				AST::InvocKind semicolon,
				AST::AsmKind is_global_asm)
{
  return parse_llvm_asm (invoc_locus, invoc, semicolon, is_global_asm);
}

tl::expected<InlineAsmContext, InlineAsmParseError>
parse_asm_arg (InlineAsmContext inline_asm_ctx)
{
  auto &parser = inline_asm_ctx.parser;
  auto last_token_id = inline_asm_ctx.last_token_id;
  auto token = parser.peek_current_token ();
  tl::optional<std::string> fm_string;
  while (token->get_id () != last_token_id)
    {
      token = parser.peek_current_token ();

      if (token->get_id () == COLON || token->get_id () == SCOPE_RESOLUTION)
	{
	  rust_error_at (
	    token->get_locus (),
	    "the legacy LLVM-style %<asm!%> syntax is no longer supported");
	  return tl::unexpected<InlineAsmParseError> (COMMITTED);
	}

      // We accept a comma token here.
      if (token->get_id () != COMMA
	  && inline_asm_ctx.consumed_comma_without_formatted_string)
	{
	  // if it is not a comma, but we consumed it previously, this is fine
	  // but we have to set it to false tho.
	  inline_asm_ctx.consumed_comma_without_formatted_string = false;
	}
      else if (token->get_id () == COMMA
	       && !inline_asm_ctx.consumed_comma_without_formatted_string)
	{
	  inline_asm_ctx.consumed_comma_without_formatted_string = false;
	  parser.skip_token ();
	}
      else if (token->get_id () == COMMA
	       && inline_asm_ctx.consumed_comma_without_formatted_string)
	{
	  // We consumed comma, and there happens to also be a comma
	  // error should be: expected expression, found `,`
	  rust_error_at (token->get_locus (), "expected expression, found %qs",
			 ",");
	  return tl::unexpected<InlineAsmParseError> (COMMITTED);
	  break;
	}

      // And if that token comma is also the trailing comma, we break
      token = parser.peek_current_token ();
      if (token->get_id () == COMMA && token->get_id () == last_token_id)
	{
	  parser.skip_token ();
	  break;
	}

      // Ok after the left paren is good, we better be parsing correctly
      // everything in here, which is operand in ABNF

      // Parse clobber abi, eat the identifier named "clobber_abi" if true
      if (check_identifier (parser, "clobber_abi"))
	{
	  auto expected = parse_clobber_abi (inline_asm_ctx);
	  if (expected.has_value ())
	    continue;
	  else if (expected.error () == COMMITTED)
	    return expected;

	  // The error type is definitely non-committed (we have checked above),
	  // we are allowed to keep on parsing
	}

      if (check_identifier (parser, "options"))
	{
	  auto expected = parse_options (inline_asm_ctx);
	  if (expected.has_value ())
	    continue;
	  else if (expected.error () == COMMITTED)
	    return expected;

	  // The error type is definitely non-committed (we have checked above),
	  // we are allowed to keep on parsing
	}

      // Ok after we have check that neither clobber_abi nor options works, the
      // only other logical choice is reg_operand

      auto expected = parse_reg_operand (inline_asm_ctx);
      if (expected.has_value ())
	continue;
      else if (expected.error () == COMMITTED)
	return expected;

      // Since parse_reg_operand is the last thing we've considered,
      // The non-committed parse error type means that we have exhausted our
      // search path

      // We then should return the error of COMMITTED, even though we have not
      // committed to anything So that the error bubbles up and we recover from
      // this error gracefully
      rust_error_at (token->get_locus (),
		     "expected operand, %s, options, or additional "
		     "template string",
		     "clobber_abi");
      return tl::unexpected<InlineAsmParseError> (COMMITTED);
    }
  return tl::expected<InlineAsmContext, InlineAsmParseError> (inline_asm_ctx);
}

tl::expected<InlineAsmContext, InlineAsmParseError>
expand_inline_asm_strings (InlineAsmContext inline_asm_ctx)
{
  auto &inline_asm = inline_asm_ctx.inline_asm;

  auto str_vec = inline_asm.get_template_strs ();

  decltype (str_vec) resulting_template_vec;
  for (auto &template_str : str_vec)
    {
      /*std::cout << template_str.symbol << std::endl;*/

      auto pieces = Fmt::Pieces::collect (template_str.symbol, false,
					  Fmt::ffi::ParseMode::InlineAsm);
      auto pieces_vec = pieces.get_pieces ();

      std::string transformed_template_str = "";
      for (size_t i = 0; i < pieces_vec.size (); i++)
	{
	  auto piece = pieces_vec[i];
	  if (piece.tag == Fmt::ffi::Piece::Tag::String)
	    {
	      transformed_template_str += piece.string._0.to_string ();
	    }
	  else if (piece.tag == Fmt::ffi::Piece::Tag::NextArgument)
	    {
	      /*    std::cout << "       " << i << ": "*/
	      /*<< piece.next_argument._0.to_string () << std::endl;*/

	      auto next_argument = piece.next_argument._0;
	      switch (piece.next_argument._0.position.tag)
		{
		case Fmt::ffi::Position::Tag::ArgumentImplicitlyIs:
		  {
		    auto idx = next_argument.position.argument_implicitly_is._0;
		    /*auto trait = next_argument.format;*/
		    /*auto arg = arguments.at (idx);*/

		    /* // FIXME(Arthur): This API sucks*/
		    /* rust_assert (arg.get_kind ().kind*/
		    /*== AST::FormatArgumentKind::Kind::Normal);*/
		    /**/
		    /* args.push_back ({arg.get_expr ().clone_expr (),
		     * trait});*/

		    transformed_template_str += "%" + std::to_string (idx);
		    // std::cout << "argument implicitly is: " << idx <<
		    // std::endl; std::cout << "transformed template str is:"
		    // << transformed_template_str << std::endl;
		    /*std::cout << "trait: " << trait.to_string () <<
		     * std::endl;*/
		    /*std::cout << "arg: " << arg.to_string () << std::endl;*/
		  }
		  break;
		case Fmt::ffi::Position::Tag::ArgumentIs:
		  {
		    auto idx = next_argument.position.argument_is._0;
		    transformed_template_str += "%" + std::to_string (idx);
		    break;
		  }
		case Fmt::ffi::Position::Tag::ArgumentNamed:
		  rust_sorry_at (inline_asm.get_locus (),
				 "unhandled argument position specifier");
		  break;
		}
	    }
	}
      template_str.symbol = transformed_template_str;
    }

  inline_asm.template_strs = str_vec;
  return inline_asm_ctx;
}

tl::optional<AST::Fragment>
parse_asm (location_t invoc_locus, AST::MacroInvocData &invoc,
	   AST::InvocKind semicolon, AST::AsmKind is_global_asm)
{
  // From the rule of asm.
  // We first parse all formatted strings. If we fail, then we return
  // tl::nullopt

  // We then parse the asm arguments. If we fail, then we return
  // tl::nullopt

  // We then validate. If we fail, then we return tl::nullopt

  // Done
  MacroInvocLexer lex (invoc.get_delim_tok_tree ().to_token_stream ());
  Parser<MacroInvocLexer> parser (lex);
  auto last_token_id = macro_end_token (invoc.get_delim_tok_tree (), parser);

  AST::InlineAsm inline_asm (invoc_locus,
			     is_global_asm == AST::AsmKind::Global);
  auto inline_asm_ctx = InlineAsmContext (inline_asm, parser, last_token_id);

  auto resulting_context = parse_format_strings (inline_asm_ctx)
			     .and_then (parse_asm_arg)
			     .and_then (validate)
			     .and_then (expand_inline_asm_strings);

  // TODO: I'm putting the validation here because the rust reference put
  // it here Per Arthur's advice we would actually do the validation in a
  // different stage. and visit on the InlineAsm AST instead of it's
  // context.
  if (resulting_context)
    {
      auto node = (*resulting_context).inline_asm.clone_expr_without_block ();

      std::vector<AST::SingleASTNode> single_vec = {};

      // If the macro invocation has a semicolon (`asm!("...");`), then we
      // need to make it a statement. This way, it will be expanded
      // properly.
      if (semicolon == AST::InvocKind::Semicoloned)
	single_vec.emplace_back (AST::SingleASTNode (
	  std::make_unique<AST::ExprStmt> (std::move (node), invoc_locus,
					   semicolon
					     == AST::InvocKind::Semicoloned)));
      else
	single_vec.emplace_back (AST::SingleASTNode (std::move (node)));

      AST::Fragment fragment_ast
	= AST::Fragment (single_vec,
			 std::vector<std::unique_ptr<AST::Token>> ());
      return fragment_ast;
    }
  else
    {
      return tl::nullopt;
    }
}

tl::expected<InlineAsmContext, InlineAsmParseError>
parse_format_strings (InlineAsmContext inline_asm_ctx)
{
  // Parse the first ever formatted string, success or not, will skip 1
  // token
  auto &parser = inline_asm_ctx.parser;
  auto last_token_id = inline_asm_ctx.last_token_id;
  auto fm_string = parse_format_string (inline_asm_ctx);

  auto &inline_asm = inline_asm_ctx.inline_asm;
  auto token = parser.peek_current_token ();
  if (fm_string == tl::nullopt)
    {
      rust_error_at (parser.peek_current_token ()->get_locus (),
		     "%s template must be a string literal", "asm");
      return tl::unexpected<InlineAsmParseError> (COMMITTED);
    }
  else
    {
      auto template_str
	= AST::TupleTemplateStr (token->get_locus (),
				 strip_double_quotes (fm_string.value ()));
      inline_asm.template_strs.push_back (template_str);
    }

  // formatted string stream

  while (parser.peek_current_token ()->get_id () != last_token_id)
    {
      if (!parser.skip_token (COMMA))
	{
	  rust_error_at (parser.peek_current_token ()->get_locus (),
			 "expected token %qs", ";");
	  return tl::unexpected<InlineAsmParseError> (COMMITTED);
	}
      // Ok after the comma is good, we better be parsing correctly
      // everything in here, which is formatted string in ABNF
      inline_asm_ctx.consumed_comma_without_formatted_string = false;

      token = parser.peek_current_token ();
      fm_string = parse_format_string (inline_asm_ctx);
      if (fm_string == tl::nullopt)
	{
	  inline_asm_ctx.consumed_comma_without_formatted_string = true;
	  break;
	}
      else
	{
	  auto template_str
	    = AST::TupleTemplateStr (token->get_locus (),
				     strip_double_quotes (fm_string.value ()));
	  inline_asm.template_strs.push_back (template_str);
	}
    }

  return inline_asm_ctx;
}

// bool
// is_label (const std::string &potential_label)
// {

//   if (potential_label.empty () || potential_label.back () != ':')
//     return false;

//   // Check if all characters before the last colon are digits
//   for (size_t i = 0; i < potential_label.length () - 1; i++)
//   {
//     if (potential_label[i] < '0' || potential_label[i] > '9')
//       return false;
//   }

//   return true;
// }

tl::expected<InlineAsmContext, InlineAsmParseError>
validate (InlineAsmContext inline_asm_ctx)
{
  return tl::expected<InlineAsmContext, InlineAsmParseError> (inline_asm_ctx);
}

tl::optional<LlvmAsmContext>
parse_llvm_templates (LlvmAsmContext ctx)
{
  auto &parser = ctx.parser;

  auto token = parser.peek_current_token ();

  if (token->get_id () == ctx.last_token_id
      || token->get_id () != STRING_LITERAL)
    {
      return tl::nullopt;
    }

  ctx.llvm_asm.get_templates ().emplace_back (token->get_locus (),
					      strip_double_quotes (
						token->as_string ()));
  ctx.parser.skip_token ();

  token = parser.peek_current_token ();
  if (token->get_id () != ctx.last_token_id && token->get_id () != COLON
      && token->get_id () != SCOPE_RESOLUTION)
    {
      // We do not handle multiple template string, we provide minimal support
      // for the black_box intrinsics.
      rust_unreachable ();
    }

  return ctx;
}

tl::optional<LlvmAsmContext>
parse_llvm_arguments (LlvmAsmContext ctx)
{
  auto &parser = ctx.parser;
  enum State
  {
    Templates = 0,
    Output,
    Input,
    Clobbers,
    Options
  } current_state
    = State::Templates;

  while (parser.peek_current_token ()->get_id () != ctx.last_token_id
	 && parser.peek_current_token ()->get_id () != END_OF_FILE)
    {
      if (parser.peek_current_token ()->get_id () == SCOPE_RESOLUTION)
	{
	  parser.skip_token (SCOPE_RESOLUTION);
	  current_state = static_cast<State> (current_state + 2);
	}
      else
	{
	  parser.skip_token (COLON);
	  current_state = static_cast<State> (current_state + 1);
	}

      switch (current_state)
	{
	case State::Output:
	  parse_llvm_outputs (ctx);
	  break;
	case State::Input:
	  parse_llvm_inputs (ctx);
	  break;
	case State::Clobbers:
	  parse_llvm_clobbers (ctx);
	  break;
	case State::Options:
	  parse_llvm_options (ctx);
	  break;
	case State::Templates:
	default:
	  rust_unreachable ();
	}
    }

  return ctx;
}

void
parse_llvm_operands (LlvmAsmContext &ctx, std::vector<AST::LlvmOperand> &result)
{
  auto &parser = ctx.parser;
  auto token = parser.peek_current_token ();
  while (token->get_id () != COLON && token->get_id () != SCOPE_RESOLUTION
	 && token->get_id () != ctx.last_token_id)
    {
      std::string constraint;
      if (token->get_id () == STRING_LITERAL)
	{
	  constraint = strip_double_quotes (token->as_string ());
	}
      parser.skip_token (STRING_LITERAL);
      parser.skip_token (LEFT_PAREN);

      token = parser.peek_current_token ();

      ParseRestrictions restrictions;
      restrictions.expr_can_be_null = true;
      auto expr = parser.parse_expr ();

      parser.skip_token (RIGHT_PAREN);

      result.emplace_back (constraint, std::move (expr));

      if (parser.peek_current_token ()->get_id () == COMMA)
	parser.skip_token (COMMA);

      token = parser.peek_current_token ();
    }
}

void
parse_llvm_outputs (LlvmAsmContext &ctx)
{
  parse_llvm_operands (ctx, ctx.llvm_asm.get_outputs ());
}

void
parse_llvm_inputs (LlvmAsmContext &ctx)
{
  parse_llvm_operands (ctx, ctx.llvm_asm.get_inputs ());
}

void
parse_llvm_clobbers (LlvmAsmContext &ctx)
{
  auto &parser = ctx.parser;
  auto token = parser.peek_current_token ();
  while (token->get_id () != COLON && token->get_id () != ctx.last_token_id)
    {
      if (token->get_id () == STRING_LITERAL)
	{
	  ctx.llvm_asm.get_clobbers ().push_back (
	    {strip_double_quotes (token->as_string ()), token->get_locus ()});
	}
      parser.skip_token (STRING_LITERAL);
      token = parser.peek_current_token ();
    }
}

void
parse_llvm_options (LlvmAsmContext &ctx)
{
  auto &parser = ctx.parser;
  auto token = parser.peek_current_token ();

  while (token->get_id () != ctx.last_token_id)
    {
      if (token->get_id () == STRING_LITERAL)
	{
	  auto token_str = strip_double_quotes (token->as_string ());

	  if (token_str == "volatile")
	    ctx.llvm_asm.set_volatile (true);
	  else if (token_str == "alignstack")
	    ctx.llvm_asm.set_align_stack (true);
	  else if (token_str == "intel")
	    ctx.llvm_asm.set_dialect (AST::LlvmInlineAsm::Dialect::Intel);
	  else
	    rust_error_at (token->get_locus (),
			   "Unknown llvm assembly option %qs",
			   token_str.c_str ());
	}
      parser.skip_token (STRING_LITERAL);

      token = parser.peek_current_token ();

      if (token->get_id () == ctx.last_token_id)
	continue;
      parser.skip_token (COMMA);
    }

  parser.skip_token ();
}

tl::optional<AST::Fragment>
parse_llvm_asm (location_t invoc_locus, AST::MacroInvocData &invoc,
		AST::InvocKind semicolon, AST::AsmKind is_global_asm)
{
  MacroInvocLexer lex (invoc.get_delim_tok_tree ().to_token_stream ());
  Parser<MacroInvocLexer> parser (lex);
  auto last_token_id = macro_end_token (invoc.get_delim_tok_tree (), parser);

  AST::LlvmInlineAsm llvm_asm{invoc_locus};

  auto asm_ctx = LlvmAsmContext (llvm_asm, parser, last_token_id);

  auto resulting_context
    = parse_llvm_templates (asm_ctx).and_then (parse_llvm_arguments);

  if (resulting_context)
    {
      auto node = (*resulting_context).llvm_asm.clone_expr_without_block ();

      std::vector<AST::SingleASTNode> single_vec = {};

      // If the macro invocation has a semicolon (`asm!("...");`), then we
      // need to make it a statement. This way, it will be expanded
      // properly.
      if (semicolon == AST::InvocKind::Semicoloned)
	single_vec.emplace_back (AST::SingleASTNode (
	  std::make_unique<AST::ExprStmt> (std::move (node), invoc_locus,
					   semicolon
					     == AST::InvocKind::Semicoloned)));
      else
	single_vec.emplace_back (AST::SingleASTNode (std::move (node)));

      AST::Fragment fragment_ast
	= AST::Fragment (single_vec,
			 std::vector<std::unique_ptr<AST::Token>> ());
      return fragment_ast;
    }
  return tl::nullopt;
}

} // namespace Rust