c67a85bee7
When debugging LLVM IR, it can be handy for clang to not discard value
names used for local variables and parameters. Compare the generated IR.
-fdiscard-value-names:
define i32 @core_sys_select(i32 %0, ptr %1, ptr %2, ptr %3, ptr %4) {
%6 = alloca i64
%7 = alloca %struct.poll_wqueues
%8 = alloca [64 x i32]
-fno-discard-value-names:
define i32 @core_sys_select(i32 %n, ptr %inp, ptr %outp, ptr %exp,
ptr %end_time) {
%expire.i = alloca i64
%table.i = alloca %struct.poll_wqueues
%stack_fds = alloca [64 x i32]
The rule for generating human readable LLVM IR (.ll) is only useful as a
debugging feature:
$ make LLVM=1 fs/select.ll
As Fangrui notes:
A LLVM_ENABLE_ASSERTIONS=off build of Clang defaults to
-fdiscard-value-names.
A LLVM_ENABLE_ASSERTIONS=on build of Clang defaults to
-fno-discard-value-names.
Explicitly enable -fno-discard-value-names so that the IR always contains
value names regardless of whether assertions were enabled or not.
Assertions generally are not enabled in releases of clang packaged by
distributions.
Link: https://github.com/ClangBuiltLinux/linux/issues/1467
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Fangrui Song <maskray@google.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.