#!/usr/bin/env python3

# Copyright 2025 The Emscripten Authors. All rights reserved.

# Emscripten is available under two separate licenses, the MIT license and the

# University of Illinois/NCSA Open Source License. Both these licenses can be

# found in the LICENSE file.

"""The functions in this file define the compiler flags that emcc passes to clang.

There are three different levels of flags, each one a superset of the next:

get_target_flags(): Defines just `-target` flags and should always be

used when calling clang, or any other llvm tool.

get_clang_flags(): In addition to the target flags this function returns all the

required compiler flags.

get_cflags(): In addition to compiler flags this function also returns pre-processor

flags. For example, include paths and macro definitions.

"""

import os

from . import building, cache, ports, shared, utils

from .cmdline import SIMD_INTEL_FEATURE_TOWER, SIMD_NEON_FLAGS

from .settings import settings

from .utils import memoize

def get_target_flags():

return ['-target', shared.get_llvm_target()]

def get_clang_flags(user_args):

flags = get_target_flags()

# if exception catching is disabled, we can prevent that code from being

# generated in the frontend

if settings.DISABLE_EXCEPTION_CATCHING and not settings.WASM_EXCEPTIONS:

flags.append('-fignore-exceptions')

if settings.INLINING_LIMIT:

flags.append('-fno-inline-functions')

if settings.PTHREADS:

if '-pthread' not in user_args:

flags.append('-pthread')

elif settings.SHARED_MEMORY:

if '-matomics' not in user_args:

flags.append('-matomics')

if '-mbulk-memory' not in user_args:

flags.append('-mbulk-memory')

if settings.MAIN_MODULE or settings.SIDE_MODULE and '-fPIC' not in user_args:

flags.append('-fPIC')

if settings.MAIN_MODULE or settings.SIDE_MODULE or settings.LINKABLE or '-fPIC' in user_args:

if not any(a.startswith('-fvisibility') for a in user_args):

# For relocatable code we default to visibility=default in emscripten even

# though the upstream backend defaults visibility=hidden. This matches the

# expectations of C/C++ code in the wild which expects undecorated symbols

# to be exported to other DSO's by default.

flags.append('-fvisibility=default')

if settings.LTO:

if not any(a.startswith('-flto') for a in user_args):

flags.append('-flto=' + settings.LTO)

# setjmp/longjmp handling using Wasm EH

# For non-LTO, '-mllvm -wasm-enable-eh' added in

# building.llvm_backend_args() sets this feature in clang. But in LTO, the

# argument is added to wasm-ld instead, so clang needs to know that EH is

# enabled so that it can be added to the attributes in LLVM IR.

if settings.SUPPORT_LONGJMP == 'wasm':

flags.append('-mexception-handling')

else:

# In LTO mode these args get passed instead at link time when the backend runs.

for a in building.llvm_backend_args():

flags += ['-mllvm', a]

return flags

@memoize

def get_cflags(user_args):

# Flags we pass to the compiler when building C/C++ code

# We add these to the user's flags (newargs), but not when building .s or .S assembly files

cflags = get_clang_flags(user_args)

cflags.append('--sysroot=' + cache.get_sysroot(absolute=True))

if settings.EMSCRIPTEN_TRACING:

cflags.append('-D__EMSCRIPTEN_TRACING__=1')

if settings.SHARED_MEMORY:

cflags.append('-D__EMSCRIPTEN_SHARED_MEMORY__=1')

if settings.WASM_WORKERS:

cflags.append('-D__EMSCRIPTEN_WASM_WORKERS__=1')

ports.add_cflags(cflags, settings)

def array_contains_any_of(hay, needles):

for n in needles:

if n in hay:

return True

if array_contains_any_of(user_args, SIMD_INTEL_FEATURE_TOWER) or array_contains_any_of(user_args, SIMD_NEON_FLAGS):

if '-msimd128' not in user_args and '-mrelaxed-simd' not in user_args:

utils.exit_with_error('passing any of ' + ', '.join(SIMD_INTEL_FEATURE_TOWER + SIMD_NEON_FLAGS) + ' flags also requires passing -msimd128 (or -mrelaxed-simd)!')

cflags += ['-D__SSE__=1']

if array_contains_any_of(user_args, SIMD_INTEL_FEATURE_TOWER[1:]):

cflags += ['-D__SSE2__=1']

if array_contains_any_of(user_args, SIMD_INTEL_FEATURE_TOWER[2:]):

cflags += ['-D__SSE3__=1']

if array_contains_any_of(user_args, SIMD_INTEL_FEATURE_TOWER[3:]):

cflags += ['-D__SSSE3__=1']

if array_contains_any_of(user_args, SIMD_INTEL_FEATURE_TOWER[4:]):

cflags += ['-D__SSE4_1__=1']

# Handle both -msse4.2 and its alias -msse4.

if array_contains_any_of(user_args, SIMD_INTEL_FEATURE_TOWER[5:]):

cflags += ['-D__SSE4_2__=1']

if array_contains_any_of(user_args, SIMD_INTEL_FEATURE_TOWER[7:]):

cflags += ['-D__AVX__=1']

if array_contains_any_of(user_args, SIMD_INTEL_FEATURE_TOWER[8:]):

cflags += ['-D__AVX2__=1']

if array_contains_any_of(user_args, SIMD_NEON_FLAGS):

cflags += ['-D__ARM_NEON__=1']

if '-nostdinc' not in user_args:

if not settings.USE_SDL:

cflags += ['-Xclang', '-iwithsysroot' + os.path.join('/include', 'fakesdl')]

cflags += ['-Xclang', '-iwithsysroot' + os.path.join('/include', 'compat')]

return cflags