On 2024-04-17 17:56, Peter Damianov wrote:
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
$ ./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 <[email protected]>
---
gcc/common.opt | 5 +++++
gcc/gcc.cc | 13 +++++++++++++
2 files changed, 18 insertions(+)
diff --git a/gcc/common.opt b/gcc/common.opt
index ad348844775..3ede2fa8552 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -422,6 +422,11 @@ 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 when
linking with
+;; many .LTRANS units.
+Driver Separate Undocumented MissingArgError(missing filename after
%qs)
+
-verbose
Driver Alias(v)
diff --git a/gcc/gcc.cc b/gcc/gcc.cc
index 728332b8153..00017964295 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. */
@@ -4607,6 +4611,10 @@ driver_handle_option (struct gcc_options *opts,
save_switch ("-o", 1, &arg, validated, true);
return true;
+ case OPT_truncate:
+ totruncate_file = arg;
+ break;
+
case OPT_pie:
#ifdef ENABLE_DEFAULT_PIE
/* -pie is turned on by default. */
@@ -9273,6 +9281,11 @@ driver::maybe_run_linker (const char *argv0)
const
option). */
error ("%s: linker input file not found: %m", outfiles[i]);
}
+
+ if (totruncate_file != NULL && linker_was_run && !seen_error ())
+ /* Truncate file specified by -truncate.
+ Used by lto-wrapper to reduce temporary disk-space usage. */
+ truncate(totruncate_file, 0);
On second thought, doing the truncation in driver::maybe_run_linker()
seems wrong.
driver::final_actions seems like the better place to put this code.
Will resubmit.
}
/* The end of "main". */
