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| author | David Faust <david.faust@oracle.com> | 2024-03-07 09:29:32 -0800 |
|---|---|---|
| committer | David Faust <david.faust@oracle.com> | 2024-03-08 10:12:42 -0800 |
| commit | 0e850eff58539fb79483664962fac6c46d65c79d (patch) | |
| tree | 2653b6bc6210b0450eb6af40bb28d124807dcebc /gcc/doc | |
| parent | ac829a89fb56cfd914d5e29ed4695e499b0dbc95 (diff) | |
| download | gcc-0e850eff58539fb79483664962fac6c46d65c79d.zip gcc-0e850eff58539fb79483664962fac6c46d65c79d.tar.gz gcc-0e850eff58539fb79483664962fac6c46d65c79d.tar.bz2 | |
bpf: add size threshold for inlining mem builtins
BPF cannot fall back on library calls to implement memmove, memcpy and
memset, so we attempt to expand these inline always if possible.
However, this inline expansion was being attempted even for excessively
large operations, which could result in gcc consuming huge amounts of
memory and hanging.
Add a size threshold in the BPF backend below which to always expand
these operations inline, and introduce an option
-minline-memops-threshold= to control the threshold. Defaults to
1024 bytes.
gcc/
* config/bpf/bpf.cc (bpf_expand_cpymem, bpf_expand_setmem): Do
not attempt inline expansion if size is above threshold.
* config/bpf/bpf.opt (-minline-memops-threshold): New option.
* doc/invoke.texi (eBPF Options) <-minline-memops-threshold>:
Document.
gcc/testsuite/
* gcc.target/bpf/inline-memops-threshold-1.c: New test.
* gcc.target/bpf/inline-memops-threshold-2.c: New test.
Diffstat (limited to 'gcc/doc')
| -rw-r--r-- | gcc/doc/invoke.texi | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index c0d604a..85c938d 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -971,7 +971,7 @@ Objective-C and Objective-C++ Dialects}. @gccoptlist{-mbig-endian -mlittle-endian -mframe-limit=@var{bytes} -mxbpf -mco-re -mno-co-re -mjmpext -mjmp32 -malu32 -mv3-atomics -mbswap -msdiv -msmov -mcpu=@var{version} --masm=@var{dialect}} +-masm=@var{dialect} -minline-memops-threshold=@var{bytes}} @emph{FR30 Options} @gccoptlist{-msmall-model -mno-lsim} @@ -25701,6 +25701,15 @@ Outputs pseudo-c assembly dialect. @end table +@opindex -minline-memops-threshold +@item -minline-memops-threshold=@var{bytes} +Specifies a size threshold in bytes at or below which memmove, memcpy +and memset shall always be expanded inline. Operations dealing with +sizes larger than this threshold would have to be be implemented using +a library call instead of being expanded inline, but since BPF doesn't +allow libcalls, exceeding this threshold results in a compile-time +error. The default is @samp{1024} bytes. + @end table @node FR30 Options |