29 Apr 2024 12:16:26 am Peter Damianov <peter0...@disroot.org>:
This commit adds a new option to the driver that truncates one file
after
linking.
Tested likeso:
$ gcc hello.c -c
$ du -h hello.o
4.0K hello.o
$ gcc hello.o -truncate hello.o
$ ./a.out
Hello world
$ du -h hello.o
$ 0 hello.o
$ gcc hello.o -truncate
gcc: error: missing filename after '-truncate'
The motivation for adding this is PR110710. It is used by lto-wrapper
to
truncate files in a shell-independent manner.
Signed-off-by: Peter Damianov <peter0...@disroot.org>
---
gcc/common.opt | 6 ++++++
gcc/gcc.cc | 14 ++++++++++++++
2 files changed, 20 insertions(+)
diff --git a/gcc/common.opt b/gcc/common.opt
index ad348844775..40cab3cb36a 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -422,6 +422,12 @@ Display target specific command line options
(including assembler and linker opt
-time
Driver Alias(time)
+;; Truncate the file specified after linking.
+;; This option is used by lto-wrapper to reduce the peak disk-usage
when
+;; linking with many .LTRANS units.
+truncate
+Driver Separate Undocumented MissingArgError(missing filename after
%qs)
+
-verbose
Driver Alias(v)
diff --git a/gcc/gcc.cc b/gcc/gcc.cc
index 728332b8153..830a4700a87 100644
--- a/gcc/gcc.cc
+++ b/gcc/gcc.cc
@@ -2138,6 +2138,10 @@ static int have_E = 0;
/* Pointer to output file name passed in with -o. */
static const char *output_file = 0;
+/* Pointer to input file name passed in with -truncate.
+ This file should be truncated after linking. */
+static const char *totruncate_file = 0;
+
/* This is the list of suffixes and codes (%g/%u/%U/%j) and the
associated
temp file. If the HOST_BIT_BUCKET is used for %j, no entry is made
for
it here. */
@@ -4538,6 +4542,11 @@ driver_handle_option (struct gcc_options *opts,
do_save = false;
break;
+ case OPT_truncate:
+ totruncate_file = arg;
+ do_save = false;
+ break;
+
case OPT____:
/* "-###"
This is similar to -v except that there is no execution
@@ -9286,6 +9295,11 @@ driver::final_actions () const
delete_failure_queue ();
delete_temp_files ();
+ if (totruncate_file != NULL && !seen_error ())
+ /* Truncate file specified by -truncate.
+ Used by lto-wrapper to reduce temporary disk-space usage. */
+ truncate(totruncate_file, 0);
+
if (print_help_list)
{
printf (("\nFor bug reporting instructions, please see:\n"));
--
2.39.2
I resubmitted the patch because the previous one had a mistake.
It didn't set "do_save" to false, so it resulted in problems like this:
./gcc/xgcc -truncate
xgcc: error: missing filename after ‘-truncate’
xgcc: fatal error: no input files
./gcc/xgcc -truncate ??
xgcc: error: unrecognized command-line option ‘-truncate’
xgcc: fatal error: no input files
Therefore regressing some tests, and not working properly.
After fixing this, I ran all of the LTO tests again and observed no
failures.
I'm not sure how I ever observed it working before, but I'm reasonably
confident this is correct now.
