There are two issues. First the gcc-strmov-store-file-names.patch
stopped working. When we introduced it, we were at 5.3.0 and 6.2.0 (see
<https://git.savannah.gnu.org/cgit/guix.git/tree/gnu/packages/gcc.scm?id=8033772363b287ca529461e575ceb4a69d7af942>).
Today, with 5.5.0 and 6.3.0 it seems to have no effect (I use ‘ltrace’
here, which shows the getenv("NIX_STORE") call, which confirms that the
‘store_reference_p’ function in that patch gets called):
--8<---------------cut here---------------start------------->8---
$ cat strmov.c
#define _GNU_SOURCE
#include <string.h>
static const char str[] = "MEMpCPY /gnu/store/THIS IS A LONG STRING, A VERY,
VERY, VERY LOOOOONG STRING";
extern char *p, *q;
#ifndef MEMCPY
# define MEMCPY memcpy
#endif
void foo (char *x, char *y)
{
/* MEMCPY (x, str, sizeof str); */
MEMCPY (y, "this is a literal /gnu/store string", 35);
}
$ guix environment --no-grafts --pure --ad-hoc -C ltrace gcc-toolchain@5 --
ltrace -f -e getenv gcc -O2 -c strmov.c
[pid 2] gcc->getenv("COLUMNS")
= nil
[pid 2] gcc->getenv("TERM")
= nil
[pid 2] gcc->getenv("GCC_EXEC_PREFIX")
= nil
[pid 2] gcc->getenv("PATH")
= "/gnu/store/c312mxd0ykdh3zi3zj13m"...
[pid 2] gcc->getenv("PATH")
= "/gnu/store/c312mxd0ykdh3zi3zj13m"...
[pid 2] gcc->getenv("COMPILER_PATH")
= nil
[pid 2] gcc->getenv("LIBRARY_PATH")
= "/gnu/store/c312mxd0ykdh3zi3zj13m"...
[pid 2] gcc->getenv("LPATH")
= nil
[pid 2] gcc->getenv("GCC_COMPARE_DEBUG")
= nil
[pid 2] gcc->getenv("GCC_ROOT")
= nil
[pid 2] gcc->getenv("BINUTILS_ROOT")
= nil
[pid 2] gcc->getenv("TMPDIR")
= "/tmp"
[pid 2] gcc->getenv("TMP")
= "/tmp"
[pid 2] gcc->getenv("TEMP")
= "/tmp"
[pid 3] --- Called exec() ---
[pid 3] gcc->getenv("COLUMNS")
= nil
[pid 3] gcc->getenv("TERM")
= nil
[pid 3] gcc->getenv("DEPENDENCIES_OUTPUT")
= nil
[pid 3] gcc->getenv("SUNPRO_DEPENDENCIES")
= nil
[pid 3] gcc->getenv("CPATH")
= nil
[pid 3] gcc->getenv("C_INCLUDE_PATH")
= "/gnu/store/c312mxd0ykdh3zi3zj13m"...
[pid 3] gcc->getenv("GCC_EXEC_PREFIX")
= nil
[pid 3] gcc->getenv("PWD")
= nil
[pid 3] gcc->getenv("NIX_STORE")
= nil
[pid 3] +++ exited (status 0) +++
[pid 2] --- SIGCHLD (Child exited) ---
[pid 4] --- Called exec() ---
[pid 4] +++ exited (status 0) +++
[pid 2] --- SIGCHLD (Child exited) ---
[pid 2] +++ exited (status 0) +++
$ objdump -S strmov.o | grep movabs
0: 48 b8 74 68 69 73 20 movabs $0x2073692073696874,%rax
11: 48 b8 61 20 6c 69 74 movabs $0x61726574696c2061,%rax
1f: 48 b8 6c 20 2f 67 6e movabs $0x732f756e672f206c,%rax
2d: 48 b8 74 6f 72 65 20 movabs $0x7274732065726f74,%rax
$ guix environment --no-grafts --pure --ad-hoc -C ltrace gcc-toolchain@6 --
ltrace -f -e getenv gcc -O2 -c strmov.c
[pid 2] gcc->getenv("COLUMNS")
= nil
[pid 2] gcc->getenv("TERM")
= nil
[pid 2] gcc->getenv("GCC_EXEC_PREFIX")
= nil
[pid 2] gcc->getenv("PATH")
= "/gnu/store/5141337yvhhjj5fhdx660"...
[pid 2] gcc->getenv("PATH")
= "/gnu/store/5141337yvhhjj5fhdx660"...
[pid 2] gcc->getenv("COMPILER_PATH")
= nil
[pid 2] gcc->getenv("LIBRARY_PATH")
= "/gnu/store/5141337yvhhjj5fhdx660"...
[pid 2] gcc->getenv("LPATH")
= nil
[pid 2] gcc->getenv("GCC_COMPARE_DEBUG")
= nil
[pid 2] gcc->getenv("GCC_ROOT")
= nil
[pid 2] gcc->getenv("BINUTILS_ROOT")
= nil
[pid 2] gcc->getenv("TMPDIR")
= "/tmp"
[pid 2] gcc->getenv("TMP")
= "/tmp"
[pid 2] gcc->getenv("TEMP")
= "/tmp"
[pid 3] --- Called exec() ---
[pid 3] gcc->getenv("COLUMNS")
= nil
[pid 3] gcc->getenv("TERM")
= nil
[pid 3] gcc->getenv("DEPENDENCIES_OUTPUT")
= nil
[pid 3] gcc->getenv("SUNPRO_DEPENDENCIES")
= nil
[pid 3] gcc->getenv("CPATH")
= nil
[pid 3] gcc->getenv("C_INCLUDE_PATH")
= "/gnu/store/5141337yvhhjj5fhdx660"...
[pid 3] gcc->getenv("GCC_EXEC_PREFIX")
= nil
[pid 3] gcc->getenv("PWD")
= nil
[pid 3] gcc->getenv("NIX_STORE")
= nil
[pid 3] +++ exited (status 0) +++
[pid 2] --- SIGCHLD (Child exited) ---
[pid 4] --- Called exec() ---
[pid 4] +++ exited (status 0) +++
[pid 2] --- SIGCHLD (Child exited) ---
[pid 2] +++ exited (status 0) +++
$ objdump -S strmov.o | grep movabs
0: 48 b8 74 68 69 73 20 movabs $0x2073692073696874,%rax
11: 48 b8 61 20 6c 69 74 movabs $0x61726574696c2061,%rax
1f: 48 b8 6c 20 2f 67 6e movabs $0x732f756e672f206c,%rax
2d: 48 b8 74 6f 72 65 20 movabs $0x7274732065726f74,%rax
--8<---------------cut here---------------end--------------->8---
On GCC 7.3.0, it works as intended:
--8<---------------cut here---------------start------------->8---
$ guix environment --no-grafts --pure --ad-hoc -C ltrace gcc-toolchain@7 --
ltrace -f -e getenv gcc -O2 -c strmov.c
[pid 2] gcc->getenv("COLUMNS")
= nil
[pid 2] gcc->getenv("TERM")
= nil
[pid 2] gcc->getenv("GCC_EXEC_PREFIX")
= nil
[pid 2] gcc->getenv("PATH")
= "/gnu/store/zahi3qjfnfq5z0bsxkggq"...
[pid 2] gcc->getenv("PATH")
= "/gnu/store/zahi3qjfnfq5z0bsxkggq"...
[pid 2] gcc->getenv("COMPILER_PATH")
= nil
[pid 2] gcc->getenv("LIBRARY_PATH")
= "/gnu/store/zahi3qjfnfq5z0bsxkggq"...
[pid 2] gcc->getenv("LPATH")
= nil
[pid 2] gcc->getenv("GCC_COMPARE_DEBUG")
= nil
[pid 2] gcc->getenv("GCC_ROOT")
= nil
[pid 2] gcc->getenv("BINUTILS_ROOT")
= nil
[pid 2] gcc->getenv("TMPDIR")
= "/tmp"
[pid 2] gcc->getenv("TMP")
= "/tmp"
[pid 2] gcc->getenv("TEMP")
= "/tmp"
[pid 3] --- Called exec() ---
[pid 3] gcc->getenv("COLUMNS")
= nil
[pid 3] gcc->getenv("TERM")
= nil
[pid 3] gcc->getenv("DEPENDENCIES_OUTPUT")
= nil
[pid 3] gcc->getenv("SUNPRO_DEPENDENCIES")
= nil
[pid 3] gcc->getenv("CPATH")
= nil
[pid 3] gcc->getenv("C_INCLUDE_PATH")
= "/gnu/store/zahi3qjfnfq5z0bsxkggq"...
[pid 3] gcc->getenv("GCC_EXEC_PREFIX")
= nil
[pid 3] gcc->getenv("PWD")
= nil
[pid 3] gcc->getenv("NIX_STORE")
= nil
[pid 3] +++ exited (status 0) +++
[pid 2] --- SIGCHLD (Child exited) ---
[pid 4] --- Called exec() ---
[pid 4] +++ exited (status 0) +++
[pid 2] --- SIGCHLD (Child exited) ---
[pid 2] +++ exited (status 0) +++
$ objdump -S strmov.o | grep movabs
$ guix environment --no-grafts --pure --ad-hoc -C ltrace gcc-toolchain@6 --
/bin/sh -c 'export NIX_STORE=/foo ; ltrace -f -e getenv gcc -O2 -c strmov.c '
[pid 3] gcc->getenv("COLUMNS")
= nil
[pid 3] gcc->getenv("TERM")
= nil
[pid 3] gcc->getenv("GCC_EXEC_PREFIX")
= nil
[pid 3] gcc->getenv("PATH")
= "/gnu/store/5141337yvhhjj5fhdx660"...
[pid 3] gcc->getenv("PATH")
= "/gnu/store/5141337yvhhjj5fhdx660"...
[pid 3] gcc->getenv("COMPILER_PATH")
= nil
[pid 3] gcc->getenv("LIBRARY_PATH")
= "/gnu/store/5141337yvhhjj5fhdx660"...
[pid 3] gcc->getenv("LPATH")
= nil
[pid 3] gcc->getenv("GCC_COMPARE_DEBUG")
= nil
[pid 3] gcc->getenv("GCC_ROOT")
= nil
[pid 3] gcc->getenv("BINUTILS_ROOT")
= nil
[pid 3] gcc->getenv("TMPDIR")
= "/tmp"
[pid 3] gcc->getenv("TMP")
= "/tmp"
[pid 3] gcc->getenv("TEMP")
= "/tmp"
[pid 4] --- Called exec() ---
[pid 4] gcc->getenv("COLUMNS")
= nil
[pid 4] gcc->getenv("TERM")
= nil
[pid 4] gcc->getenv("DEPENDENCIES_OUTPUT")
= nil
[pid 4] gcc->getenv("SUNPRO_DEPENDENCIES")
= nil
[pid 4] gcc->getenv("CPATH")
= nil
[pid 4] gcc->getenv("C_INCLUDE_PATH")
= "/gnu/store/5141337yvhhjj5fhdx660"...
[pid 4] gcc->getenv("GCC_EXEC_PREFIX")
= nil
[pid 4] gcc->getenv("PWD")
= "/home/ludo/src/guix"
[pid 4] gcc->getenv("NIX_STORE")
= "/foo"
[pid 4] gcc->getenv("NIX_STORE")
= "/foo"
[pid 4] +++ exited (status 0) +++
[pid 3] --- SIGCHLD (Child exited) ---
[pid 5] --- Called exec() ---
[pid 5] +++ exited (status 0) +++
[pid 3] --- SIGCHLD (Child exited) ---
[pid 3] +++ exited (status 0) +++
$ objdump -S strmov.o | grep movabs
0: 48 b8 74 68 69 73 20 movabs $0x2073692073696874,%rax
11: 48 b8 61 20 6c 69 74 movabs $0x61726574696c2061,%rax
1f: 48 b8 6c 20 2f 67 6e movabs $0x732f756e672f206c,%rax
2d: 48 b8 74 6f 72 65 20 movabs $0x7274732065726f74,%rax
--8<---------------cut here---------------end--------------->8---
The second issue is that the patch only ever worked with literal
strings. It does not “see” strings in constant arrays like the ‘str’
array in the example above.
The gconv-module file name mentioned in the first message in this bug
report is an example of a string assigned to a static array, in
iconv/gconv_conf.c:
/* This is the default path where we look for module lists. */
static const char default_gconv_path[] = GCONV_PATH;
Ludo’.
