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author | Nick Desaulniers <ndesaulniers@google.com> | 2022-10-14 19:53:02 +0300 |
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committer | Masahiro Yamada <masahiroy@kernel.org> | 2022-10-14 23:22:29 +0300 |
commit | c67a85bee78db74c6889a5ca645c3763ad23d863 (patch) | |
tree | 3a7058187272973b230a962bd30832a1e6610f0f /Makefile | |
parent | 04518e4c2edc78bc90b4651d50c4aad48d09ac23 (diff) | |
download | linux-c67a85bee78db74c6889a5ca645c3763ad23d863.tar.xz |
kbuild: add -fno-discard-value-names to cmd_cc_ll_c
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>
Diffstat (limited to 'Makefile')
0 files changed, 0 insertions, 0 deletions