build_tools/wasm/libc/BUILD.bazel

# Copyright 2026 The IREE Authors
#
# Licensed under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

# Freestanding libc for wasm32.
#
# Provides C standard library headers and implementations for building the
# IREE runtime as a standalone wasm module. No system libc, no Emscripten —
# just enough to compile and link C code targeting wasm32-unknown-unknown.
#
# Headers are in include/ and work as a -isystem include path via the wasm32
# cc_toolchain. The implementations are linked via the :libc cc_library.
#
# Components:
#   dlmalloc    Memory allocation (Doug Lea's malloc, MIT-0 license).
#   sbrk        Thin wrapper over wasm memory.grow, initialized from __heap_base.
#   string      memcmp, memchr, strlen, strcmp, strstr, etc.
#               (memcpy/memmove/memset are wasm builtins via -mbulk-memory.)
#   strtol      Integer/float string-to-number conversion.
#   ctype       ASCII character classification (table-driven).
#   stdio       printf wrappers (eyalroz/printf), stream I/O via JS imports.
#   stdlib      abs, div, rand, getenv.
#   abort       abort/exit/assert_fail via JS imports.
#   errno       Global errno variable.
#   unistd      write() via JS import, other POSIX stubs.

load("//build_tools/bazel:iree_wasm_library.bzl", "iree_wasm_cc_library")

package(default_visibility = ["//visibility:public"])

filegroup(
    name = "headers",
    srcs = glob(["include/**/*.h"]),
)

# JS implementation of the iree_syscall wasm imports.
# Provides the import object (write, clock_now_ns, exit, assert_fail)
# that the C code in syscall_imports.h declares via __attribute__((import_module)).
iree_wasm_cc_library(
    name = "syscall_imports",
    srcs = ["src/syscall_imports.js"],
    module = "iree_syscall",
)

cc_library(
    name = "libc",
    srcs = [
        "src/abort.c",
        "src/aligned_alloc.c",
        "src/ctype.c",
        "src/dlmalloc.c",
        "src/errno.c",
        "src/sbrk.c",
        "src/stdio.c",
        "src/stdlib.c",
        "src/string.c",
        "src/strtol.c",
        "src/syscall_imports.h",
        "src/unistd.c",
    ],
    hdrs = glob(["include/**/*.h"]),
    includes = ["include"],
    target_compatible_with = ["@platforms//cpu:wasm32"],
    deps = [
        ":syscall_imports",
        "@dlmalloc",
    ],
)