[libc] Stop depending on .cpp files libcxx_shared_headers library. #133999

vonosmas · 2025-04-01T22:48:17Z

Fix two instances of libcxx_shared_headers depending on .cpp files (in Bazel build):

Don't depend on exit syscall in LIBC_ASSERT implementation. This dependency is not used, since LIBC_ASSERT always uses system <assert.h> in the overlay mode, which is the only mode supported by Bazel.
Don't depend on libc_errno in str-to-float and str-to-integer conversions. We only need the ERANGE value, which can be obtained from the proxy header instead.

Fix two instances of libcxx_shared_headers depending on .cpp files (in Bazel build): * Don't depend on exit syscall in LIBC_ASSERT implementation. This dependency is not used, since LIBC_ASSERT always uses system <assert.h> in the overlay mode, which is the only mode supported by Bazel. * Don't depend on libc_errno in str-to-float and str-to-integer conversions. We only need the ERANGE value, which can be obtained from the proxy header instead.

llvmbot · 2025-04-01T22:48:54Z

@llvm/pr-subscribers-libc

Author: Alexey Samsonov (vonosmas)

Changes

Fix two instances of libcxx_shared_headers depending on .cpp files (in Bazel build):

Don't depend on exit syscall in LIBC_ASSERT implementation. This dependency is not used, since LIBC_ASSERT always uses system <assert.h> in the overlay mode, which is the only mode supported by Bazel.
Don't depend on libc_errno in str-to-float and str-to-integer conversions. We only need the ERANGE value, which can be obtained from the proxy header instead.

Full diff: https://github.com/llvm/llvm-project/pull/133999.diff

5 Files Affected:

(modified) libc/src/__support/CMakeLists.txt (+2-2)
(modified) libc/src/__support/libc_assert.h (+1-1)
(modified) libc/src/__support/str_to_float.h (+1-1)
(modified) libc/src/__support/str_to_integer.h (+1-1)
(modified) utils/bazel/llvm-project-overlay/libc/BUILD.bazel (+3-23)

diff --git a/libc/src/__support/CMakeLists.txt b/libc/src/__support/CMakeLists.txt
index 17f03a6b6c4a0..f92499fdbf451 100644
--- a/libc/src/__support/CMakeLists.txt
+++ b/libc/src/__support/CMakeLists.txt
@@ -165,7 +165,7 @@ add_header_library(
   DEPENDS
     .ctype_utils
     .str_to_num_result
-    libc.src.errno.errno
+    libc.hdr.errno_macros
     libc.src.__support.CPP.limits
     libc.src.__support.CPP.type_traits
     libc.src.__support.common
@@ -217,6 +217,7 @@ add_header_library(
     .str_to_integer
     .str_to_num_result
     .uint128
+    libc.hdr.errno_macros
     libc.src.__support.common
     libc.src.__support.CPP.bit
     libc.src.__support.CPP.limits
@@ -226,7 +227,6 @@ add_header_library(
     libc.src.__support.macros.config
     libc.src.__support.macros.null_check
     libc.src.__support.macros.optimization
-    libc.src.errno.errno
 )
 
 add_header_library(
diff --git a/libc/src/__support/libc_assert.h b/libc/src/__support/libc_assert.h
index 3db179ff67212..ada1795ccb80a 100644
--- a/libc/src/__support/libc_assert.h
+++ b/libc/src/__support/libc_assert.h
@@ -9,7 +9,6 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_LIBC_ASSERT_H
 #define LLVM_LIBC_SRC___SUPPORT_LIBC_ASSERT_H
 
-#include "src/__support/macros/config.h"
 #if defined(LIBC_COPT_USE_C_ASSERT) || !defined(LIBC_FULL_BUILD)
 
 // The build is configured to just use the public <assert.h> API
@@ -25,6 +24,7 @@
 #include "src/__support/OSUtil/io.h"
 #include "src/__support/integer_to_string.h"
 #include "src/__support/macros/attributes.h"   // For LIBC_INLINE
+#include "src/__support/macros/config.h"
 #include "src/__support/macros/optimization.h" // For LIBC_UNLIKELY
 
 namespace LIBC_NAMESPACE_DECL {
diff --git a/libc/src/__support/str_to_float.h b/libc/src/__support/str_to_float.h
index 48c88309c58e9..0748e1cb8a8b4 100644
--- a/libc/src/__support/str_to_float.h
+++ b/libc/src/__support/str_to_float.h
@@ -15,6 +15,7 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_STR_TO_FLOAT_H
 #define LLVM_LIBC_SRC___SUPPORT_STR_TO_FLOAT_H
 
+#include "hdr/errno_macros.h" // For ERANGE
 #include "src/__support/CPP/bit.h"
 #include "src/__support/CPP/limits.h"
 #include "src/__support/CPP/optional.h"
@@ -31,7 +32,6 @@
 #include "src/__support/str_to_integer.h"
 #include "src/__support/str_to_num_result.h"
 #include "src/__support/uint128.h"
-#include "src/errno/libc_errno.h" // For ERANGE
 
 #include <stdint.h>
 
diff --git a/libc/src/__support/str_to_integer.h b/libc/src/__support/str_to_integer.h
index 9212ad25d0820..76a99a8948941 100644
--- a/libc/src/__support/str_to_integer.h
+++ b/libc/src/__support/str_to_integer.h
@@ -15,6 +15,7 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_STR_TO_INTEGER_H
 #define LLVM_LIBC_SRC___SUPPORT_STR_TO_INTEGER_H
 
+#include "hdr/errno_macros.h" // For ERANGE
 #include "src/__support/CPP/limits.h"
 #include "src/__support/CPP/type_traits.h"
 #include "src/__support/CPP/type_traits/make_unsigned.h"
@@ -24,7 +25,6 @@
 #include "src/__support/macros/config.h"
 #include "src/__support/str_to_num_result.h"
 #include "src/__support/uint128.h"
-#include "src/errno/libc_errno.h" // For ERANGE
 
 namespace LIBC_NAMESPACE_DECL {
 namespace internal {
diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
index 77aa75362c71d..4d264b955cf66 100644
--- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
@@ -841,12 +841,6 @@ libc_support_library(
 libc_support_library(
     name = "__support_libc_assert",
     hdrs = ["src/__support/libc_assert.h"],
-    deps = [
-        ":__support_integer_to_string",
-        ":__support_macros_attributes",
-        ":__support_osutil_exit",
-        ":__support_osutil_io",
-    ],
 )
 
 libc_support_library(
@@ -868,7 +862,7 @@ libc_support_library(
         ":__support_ctype_utils",
         ":__support_str_to_num_result",
         ":__support_uint128",
-        ":errno",
+        ":hdr_errno_macros",
     ],
 )
 
@@ -892,7 +886,7 @@ libc_support_library(
         ":__support_str_to_integer",
         ":__support_str_to_num_result",
         ":__support_uint128",
-        ":errno",
+        ":hdr_errno_macros",
     ],
 )
 
@@ -1590,21 +1584,6 @@ libc_support_library(
 
 ########################## externally shared targets ###########################
 
-# TODO: Remove this once downstream users are migrated to libcxx_shared_headers.
-libc_support_library(
-    name = "libc_external_common",
-    hdrs = glob(
-        ["shared/*.h"],
-        exclude = ["shared/rpc_server.h"],
-    ),
-    deps = [
-        ":__support_common",
-        ":__support_fputil_fp_bits",
-        ":__support_str_to_float",
-        ":__support_str_to_integer",
-    ],
-)
-
 libc_header_library(
     name = "libcxx_shared_headers",
     hdrs = [
@@ -1911,6 +1890,7 @@ libc_support_library(
         ":__support_fputil_fma",
         ":__support_fputil_multiply_add",
         ":__support_fputil_polyeval",
+        ":__support_integer_literals",
     ],
 )

michaelrj-google

LGTM, thanks for the cleanup

LLVM 20 release contains a bug that it one of the headers in `libc/src/__support` directory includes a header from `libc/src/errno`, which is not one of the header directories that are meant to be included: https://github.com/llvm/llvm-project/blob/ec28b8f9cc7f2ac187d8a617a6d08d5e56f9120e/libc/src/__support/str_to_float.h#L34 I was told (llvm/llvm-project#91651 (comment)) this was a bug that was fixed in llvm/llvm-project#133999. Whether this fix will be backported to later version of LLVM 20 release is unclear. To avoid importing files from `libc/src`, this applies the fix here as well.

This updates libcxx and libcxxabi to LLVM 20.1.4: https://github.com/llvm/llvm-project/releases/tag/llvmorg-20.1.4 Before going into each additional change of the PR, these are some noteworthy changes from this LLVM release: - Freezing C++03 headers - RFC: https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc/77319 - PRs: - llvm/llvm-project#108999 - llvm/llvm-project#109000 - llvm/llvm-project#109001 - llvm/llvm-project#109002 - This copies libc++ headers of the last LLVM 19 release into a separate directory (https://github.com/llvm/llvm-project/tree/main/libcxx/include/__cxx03) and redirects all C++03 workflow there. The motivation is not to fix C++03 related changes unless they are critical bugs, and simplifies the main headers. So the main headers are like ``` #if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS) # include <__cxx03/algorithm> #else ... main header content ... ``` As you can see it looks like we can avoid opting into this by not defining `_LIBCPP_USE_FROZEN_CXX03_HEADERS` at the moment. I think their eventual goal is to remove C++03 support from the main headers but it hasn't seem to have happened yet and I don't know what their timeline for that is. Adding that `__cxx03` directory increases the header size by 10MB. We can get away not using them by not defining `_LIBCPP_USE_FROZEN_CXX03_HEADERS` in this release, so this update does not include that directory. - Sharing of headers between libc++ and libc (Project Hand in Hand) - RFC: https://discourse.llvm.org/t/rfc-project-hand-in-hand-llvm-libc-libc-code-sharing/77701 - PR: llvm/llvm-project#91651 (More are likely to come) This tries to share some libc headers from libcxx. libcxx's source files can depend on headers from `libc/shared`, `libc/src/__support`, `libc/include/llvm-libc-macros`, and `libc/include/llvm-libc-types`. And it turns out libcxx can also depend on `libc/hdr`, even though the directory is not in the diagram in the RFC. These headers can be only included from `libcxx/src` and not `libcxx/include`, to prevent libcxx's API from changing. So these headers don't need to be copied into `cache/`. - Locale API reimplementation It doesn't seem to have an RFC, but the PRs are: - llvm/llvm-project#113737 - llvm/llvm-project#115176 - llvm/llvm-project#115752 - llvm/llvm-project#122489 It looks this aims provide a new way to define locale API for each platform. Currently Apple, FreeBSD, MSVCRT, and Fuschia are using the new API and the others are still using the old one: https://github.com/llvm/llvm-project/blob/ec28b8f9cc7f2ac187d8a617a6d08d5e56f9120e/libcxx/include/__locale_dir/locale_base_api.h#L116-L138 For our purpose, adding `if defined(__EMSCRIPTEN__)` entry to the list of "old" list seems to work for the moment, but we may need to move to the new way eventually later. --- Additional changes: - Copy `vendor/llvm/default_assertion_handler.in` to `__assertion_handler`: aa53648 Our previous `__assertion_handler` was copied from `libcxx/vendor/llvm/default_assertion_handler.in`. This updates our `__assertion_handler` to the new `libcxx/vendor/llvm/default_assertion_handler.in`. For what this file is, see the PR description of #22994, with which the file was added. - Remove `libcxx/include/__cxx03` directory: d646f6b As I described in "Freezing C++ headers" above, C++03 headers were copied to `include/cxx03` to be "frozen". But by not defining `_LIBCPP_USE_FROZEN_CXX03_HEADERS` we can still use the main headers. This new `__cxx03` header directory is almost 10M and we are not using it in this update, this deletes it. - Define more variables in `__config_site`: 9912236 libcxx decides to almost all configuration macros to be defined. So before it tested whether a macro was defined/undefined, and now it assumes it is defined and tests whether its value is 1/0. Before llvm/llvm-project#112094 `_config_site.in` used to use `#cmakedefine`, which only defined variables when they were enabled, but now it uses `#cmakedefine01`, which always defines variables and assigns 1 or 0 depending on whether the feature is enabled. So this change adds `#define` to each variable that `_config_site.in` has an entry of. The value assigned is 1 if it was defined in our previous Emscripten environment and 0 if not. - Fix Emscripten's locale: 2ae01b0 Before, the code was like https://github.com/emscripten-core/emscripten/blob/dc1abd514b1bade135a01a4453a9ff6def0793b6/system/lib/libcxx/include/__locale_dir/locale_base_api.h#L12-L30 But now they are divided into two parts, one using the new API and the other using old. See "Locale API reimplementation" above. https://github.com/llvm/llvm-project/blob/ec28b8f9cc7f2ac187d8a617a6d08d5e56f9120e/libcxx/include/__locale_dir/locale_base_api.h#L116-L138 This adds Emscripten in the beginning of the "old" API list. (This has to be the beginning; see #23414) - Import libc headers used by libcxx: 12a4ee4, 12a4ee4 and 43c8ce4 This imports a part of libc headers into `system/lib/llvm-libc`. The imported directories are: - `libc/shared` - `libc/src/__support` - `libc/include/llvm-libc-macros` - `libc/include/llvm-libc-types` - `libc/hdr` See "sharing of headers between libc+ and libc" above for details. This also applies llvm/llvm-project#133999, which is a bugfix that has not be backported, which fixes the bug of including from a wrong directory. - `std::uncaught_exception` -> `std::uncaught_exceptions`: 1bf4e78 `std::uncaught_exception` has been deprecated in C++17, so it generates a warning (which we treat as an error). Replaced it with `std::uncaught_exceptions`, which returns the number of uncaught exceptions (but can still be used as a boolean in the test). - Remove `ryu_constants.h` and `ryu_long_double_constants.h` from libc: 5767ac4 These are not used from libcxx and `ryu_long_double_constants.h` is huge (12M).

This updates libcxx and libcxxabi to LLVM 20.1.4: https://github.com/llvm/llvm-project/releases/tag/llvmorg-20.1.4 Before going into each additional change of the PR, these are some noteworthy changes from this LLVM release: - Freezing C++03 headers - RFC: https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc/77319 - PRs: - llvm/llvm-project#108999 - llvm/llvm-project#109000 - llvm/llvm-project#109001 - llvm/llvm-project#109002 - This copies libc++ headers of the last LLVM 19 release into a separate directory (https://github.com/llvm/llvm-project/tree/main/libcxx/include/__cxx03) and redirects all C++03 workflow there. The motivation is not to fix C++03 related changes unless they are critical bugs, and simplifies the main headers. So the main headers are like ``` #if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS) # include <__cxx03/algorithm> #else ... main header content ... ``` As you can see it looks like we can avoid opting into this by not defining `_LIBCPP_USE_FROZEN_CXX03_HEADERS` at the moment. I think their eventual goal is to remove C++03 support from the main headers but it hasn't seem to have happened yet and I don't know what their timeline for that is. Adding that `__cxx03` directory increases the header size by 10MB. We can get away not using them by not defining `_LIBCPP_USE_FROZEN_CXX03_HEADERS` in this release, so this update does not include that directory. - Sharing of headers between libc++ and libc (Project Hand in Hand) - RFC: https://discourse.llvm.org/t/rfc-project-hand-in-hand-llvm-libc-libc-code-sharing/77701 - PR: llvm/llvm-project#91651 (More are likely to come) This tries to share some libc headers from libcxx. libcxx's source files can depend on headers from `libc/shared`, `libc/src/__support`, `libc/include/llvm-libc-macros`, and `libc/include/llvm-libc-types`. And it turns out libcxx can also depend on `libc/hdr`, even though the directory is not in the diagram in the RFC. These headers can be only included from `libcxx/src` and not `libcxx/include`, to prevent libcxx's API from changing. So these headers don't need to be copied into `cache/`. - Locale API reimplementation It doesn't seem to have an RFC, but the PRs are: - llvm/llvm-project#113737 - llvm/llvm-project#115176 - llvm/llvm-project#115752 - llvm/llvm-project#122489 It looks this aims provide a new way to define locale API for each platform. Currently Apple, FreeBSD, MSVCRT, and Fuschia are using the new API and the others are still using the old one: https://github.com/llvm/llvm-project/blob/ec28b8f9cc7f2ac187d8a617a6d08d5e56f9120e/libcxx/include/__locale_dir/locale_base_api.h#L116-L138 For our purpose, adding `if defined(__EMSCRIPTEN__)` entry to the list of "old" list seems to work for the moment, but we may need to move to the new way eventually later. --- Additional changes: - Copy `vendor/llvm/default_assertion_handler.in` to `__assertion_handler`: emscripten-core@aa53648 Our previous `__assertion_handler` was copied from `libcxx/vendor/llvm/default_assertion_handler.in`. This updates our `__assertion_handler` to the new `libcxx/vendor/llvm/default_assertion_handler.in`. For what this file is, see the PR description of emscripten-core#22994, with which the file was added. - Remove `libcxx/include/__cxx03` directory: emscripten-core@d646f6b As I described in "Freezing C++ headers" above, C++03 headers were copied to `include/cxx03` to be "frozen". But by not defining `_LIBCPP_USE_FROZEN_CXX03_HEADERS` we can still use the main headers. This new `__cxx03` header directory is almost 10M and we are not using it in this update, this deletes it. - Define more variables in `__config_site`: emscripten-core@9912236 libcxx decides to almost all configuration macros to be defined. So before it tested whether a macro was defined/undefined, and now it assumes it is defined and tests whether its value is 1/0. Before llvm/llvm-project#112094 `_config_site.in` used to use `#cmakedefine`, which only defined variables when they were enabled, but now it uses `#cmakedefine01`, which always defines variables and assigns 1 or 0 depending on whether the feature is enabled. So this change adds `#define` to each variable that `_config_site.in` has an entry of. The value assigned is 1 if it was defined in our previous Emscripten environment and 0 if not. - Fix Emscripten's locale: emscripten-core@2ae01b0 Before, the code was like https://github.com/emscripten-core/emscripten/blob/dc1abd514b1bade135a01a4453a9ff6def0793b6/system/lib/libcxx/include/__locale_dir/locale_base_api.h#L12-L30 But now they are divided into two parts, one using the new API and the other using old. See "Locale API reimplementation" above. https://github.com/llvm/llvm-project/blob/ec28b8f9cc7f2ac187d8a617a6d08d5e56f9120e/libcxx/include/__locale_dir/locale_base_api.h#L116-L138 This adds Emscripten in the beginning of the "old" API list. (This has to be the beginning; see emscripten-core#23414) - Import libc headers used by libcxx: emscripten-core@12a4ee4, emscripten-core@12a4ee4 and emscripten-core@43c8ce4 This imports a part of libc headers into `system/lib/llvm-libc`. The imported directories are: - `libc/shared` - `libc/src/__support` - `libc/include/llvm-libc-macros` - `libc/include/llvm-libc-types` - `libc/hdr` See "sharing of headers between libc+ and libc" above for details. This also applies llvm/llvm-project#133999, which is a bugfix that has not be backported, which fixes the bug of including from a wrong directory. - `std::uncaught_exception` -> `std::uncaught_exceptions`: emscripten-core@1bf4e78 `std::uncaught_exception` has been deprecated in C++17, so it generates a warning (which we treat as an error). Replaced it with `std::uncaught_exceptions`, which returns the number of uncaught exceptions (but can still be used as a boolean in the test). - Remove `ryu_constants.h` and `ryu_long_double_constants.h` from libc: emscripten-core@5767ac4 These are not used from libcxx and `ryu_long_double_constants.h` is huge (12M).

vonosmas requested a review from michaelrj-google April 1, 2025 22:48

vonosmas requested review from aaronmondal, keith and rupprecht as code owners April 1, 2025 22:48

llvmbot added libc bazel "Peripheral" support tier build system: utils/bazel labels Apr 1, 2025

jhuber6 approved these changes Apr 1, 2025

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lntue approved these changes Apr 1, 2025

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michaelrj-google approved these changes Apr 1, 2025

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vonosmas merged commit 07504af into llvm:main Apr 1, 2025
19 checks passed

vonosmas deleted the libc-bazel-hih branch April 1, 2025 23:23

michaelrj-google mentioned this pull request May 14, 2025

[libcxx][libc] Hand in Hand PoC with from_chars #91651

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aheejin added a commit to aheejin/emscripten that referenced this pull request May 15, 2025

Apply llvm/llvm-project#133999

d9146ce

aheejin mentioned this pull request May 16, 2025

Update libcxx and libcxxabi to LLVM 20.1.4 emscripten-core/emscripten#24346

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