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[libc] Add wasm support for some submodules in llvm-libc. #154383

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[libc] Add wasm support for some submodules in llvm-libc. #154383

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50c3b02
[libc] Add wasm support for some submodules in
google-yfyang Aug 19, 2025
062e630
Create an emscripten-specific platform errors.h
google-yfyang Aug 19, 2025
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2 changes: 2 additions & 0 deletions libc/src/__support/StringUtil/platform_errors.h
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Expand Up @@ -11,6 +11,8 @@

#if defined(__linux__) || defined(__Fuchsia__)
#include "tables/linux_platform_errors.h"
#elif defined(__EMSCRIPTEN__)
#include "tables/emscripten_platform_errors.h"
#else
#include "tables/minimal_platform_errors.h"
#endif
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26 changes: 26 additions & 0 deletions libc/src/__support/StringUtil/tables/emscripten_platform_errors.h
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@@ -0,0 +1,26 @@
//===-- Map of error numbers to strings for the Emscripten platform --*- C++ -*-===//
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this line is over 80 columns, meaning it's going to get messed up by auto-formatters. Please make it exactly 80 columns

//
// Part of the LLVM Project, 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
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_LIBC_SRC___SUPPORT_STRINGUTIL_TABLES_EMSCRPITEN_PLATFORM_ERRORS_H
#define LLVM_LIBC_SRC___SUPPORT_STRINGUTIL_TABLES_EMSCRPITEN_PLATFORM_ERRORS_H

#include "posix_errors.h"
#include "src/__support/macros/config.h"
#include "stdc_errors.h"

namespace LIBC_NAMESPACE_DECL {

LIBC_INLINE_VAR constexpr auto PLATFORM_ERRORS =
STDC_ERRORS + POSIX_ERRORS;

LIBC_INLINE_VAR constexpr auto PLATFORM_ERRNO_NAMES =
STDC_ERRNO_NAMES + POSIX_ERRNO_NAMES;

} // namespace LIBC_NAMESPACE_DECL

#endif // LLVM_LIBC_SRC___SUPPORT_STRINGUTIL_TABLES_EMSCRPITEN_PLATFORM_ERRORS_H
5 changes: 5 additions & 0 deletions libc/src/__support/StringUtil/tables/posix_errors.h
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Expand Up @@ -63,7 +63,12 @@ LIBC_INLINE_VAR constexpr MsgTable<76> POSIX_ERRORS = {
MsgMapping(EPROTO, "Protocol error"),
MsgMapping(EMULTIHOP, "Multihop attempted"),
MsgMapping(EBADMSG, "Bad message"),
#ifdef __EMSCRIPTEN__
// For now, match the musl string
MsgMapping(EOVERFLOW, "Value too large for data type"),
#else
MsgMapping(EOVERFLOW, "Value too large for defined data type"),
#endif
MsgMapping(ENOTSOCK, "Socket operation on non-socket"),
MsgMapping(EDESTADDRREQ, "Destination address required"),
MsgMapping(EMSGSIZE, "Message too long"),
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5 changes: 5 additions & 0 deletions libc/src/__support/StringUtil/tables/stdc_errors.h
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Expand Up @@ -16,7 +16,12 @@
namespace LIBC_NAMESPACE_DECL {

LIBC_INLINE_VAR constexpr const MsgTable<4> STDC_ERRORS = {
#ifdef __EMSCRIPTEN__
// For now, match the musl name for errno 0.
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is the intention for emscripten to use these other error strings long-term or do you intend to switch?

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My understanding is that we will clean this up once we can significant real users of llvm-libc on emscripten. @sbc100 probably knows about it more than I do.

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I guess it depends on the timeline. We have unit tests that currently depend on the explict strings used in musl. We have a new options if we want to remove this patch:

  1. Update the unit tests to accept both string options
  2. Update our musl fork to use the llvm-libc strings
  3. Remove our support for musl completely and switch the tests to expect llvm-libc strings.

BTW, where did these specific string come from? Is there a reason to prefer "No error information" over "Success"? I suppose the former is technically more accurate but the later might be more inline with user expectations?

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I'm leaning towards (2) since we already maintain a musl fork anyway and have no plans to upstream it (unlike our llvm-libc changed).

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Okay. That sounds reasonable. But I presume that no users are going to be affected by this musl change?

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Only users whose code is sensitive the these exact strings like our unit tests are. Seems unlikely, but conceivable.

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I think the existing strings in LLVM-libc are meant to match glibc.

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I am trying to land the change to update the musl fork in emscripten first so that we no longer need these lines.

MsgMapping(0, "No error information"),
#else
MsgMapping(0, "Success"),
#endif
MsgMapping(EDOM, "Numerical argument out of domain"),
MsgMapping(ERANGE, "Numerical result out of range"),
MsgMapping(EILSEQ, "Invalid or incomplete multibyte or wide character"),
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4 changes: 4 additions & 0 deletions libc/src/__support/macros/properties/architectures.h
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Expand Up @@ -41,6 +41,10 @@
#define LIBC_TARGET_ARCH_IS_ARM
#endif

#if defined(__wasm__)
#define LIBC_TARGET_ARCH_IS_WASM
#endif

#if defined(__aarch64__) || defined(__arm64__) || defined(_M_ARM64)
#define LIBC_TARGET_ARCH_IS_AARCH64
#endif
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22 changes: 22 additions & 0 deletions libc/src/setjmp/wasm/sigsetjmp.cpp
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@@ -0,0 +1,22 @@
//===-- Implementation of sigsetjmp ---------------------------------------===//
//
// Part of the LLVM Project, 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
//
//===----------------------------------------------------------------------===//

#include "src/setjmp/sigsetjmp.h"
#include "hdr/offsetof_macros.h"
#include "src/__support/common.h"
#include "src/__support/macros/config.h"

#if !defined(LIBC_TARGET_ARCH_IS_WASM)
#error "Invalid file include"
#endif

namespace LIBC_NAMESPACE_DECL {
[[gnu::returns_twice]] int sigsetjmp(jmp_buf sigjmp_buf, int savesigs) {
return setjmp(sigjmp_buf);
}
}
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