* Documentation is now in "docs".
* Source code is now in "src".
* Misc. fixes here and there so that everything still works.
I think I got everything in this commit, but I only tested this
on Linux (Make) and Windows (CMake), so I might've messed
something up on other platforms...
* define targetos=Windows when --enable-tcc32-mingw, --enable-cygwin, ...
* use TARGETOS insteed HOST_OS when selecting PROGS
* use "$(tccdir)" insteed $(tccdir) on install (spaces in path)
* install tcc.exe too
* produce bcheck.o when cross-compiling too (lib/Makefile)
* force bcheck.o linking by compiling inside tcc_set_output_type()
a dummy program with local array. Otherwise bcheck.o may be not linked.
* replace %xz format specifier with %p in bcheck (don't supported on
Windows)
* call a __bound_init when __bound_ptr_add, __bound_ptr_indir,
__bound_new_region, __bound_delete_region called.
This is because a __bound_init inside ".init" section is not called
on Windows for unknown reason.
* print on stderr a message when an illegal pointer is returned:
there is no segmentation violation on Windows for a program
compiled with "tcc -b"
* remove "C:" subdir on clean if $HOST_OS = "Linux"
* default CFLAGS="-Wall -g -O0" insteed CFLAGS="-Wall -g -O2"
to speed up compilation and more precise debugging.
- care about __attribute__ redefinition in the system headers
- an invalid pointer must be returned when (addr >= e->size),
and not (addr > e->size)
A test program:
#include <stdio.h>
#include <stdlib.h>
int main ()
{
int v[10];
fprintf(stderr, "&v[0] = %p\n", &v[0]);
fprintf(stderr, "&v[10] = %p\n", &v[10]);
exit(1);
return 0;
}
// tcc -b test.c
The output before a patch:
&v[0] = 0xbf929d8c
&v[10] = 0xbf929db4
The output after a patch:
&v[0] = 0xbff6e33c
&v[10] = 0xfffffffe
On Linux 32: sizeof(long)=32 == sizeof(void *)=32
on Linux 64: sizeof(long)=64 == sizeof(void *)=64
on Windows 64: sizeof(long)=32 != sizeof(void *)=64
Some structs are passed in registers. When they need more than
one the implementation of __va_arg on x86-64 didn't correctly account
for this. This fixes only the cases where the structs consist of
integer types, as there the register save area is consecutive.
Fixes some tests from 73_arm64.c, but still leaves those failing
that use floating point in the large-but-regpassed structs.
__clear_cache is defined in lib-arm64.c with a single call to
__arm64_clear_cache, which is the real built-in function and is
turned into inline assembler by gen_clear_cache in arm64-gen.c
A test program:
/* result of the new version inroduced in 4ad186c5ef: t2a = 44100312 */
#include<stdio.h>
int main() {
int t1 = 176401255;
float f = 0.25f;
int t2a = (int)(t1 * f); // must be 44100313
int t2b = (int)(t1 * (float)0.25f);
printf("t2a=%d t2b=%d \n",t2a,t2b);
return 0;
}
produce a
i386-win-mingw32-tcc
i386-win-tcc
x86_64-win-mingw32-tcc
x86_64-win-tcc
arm-win-mingw32ce-tcc
arm-win-tcc
instead of the
i386-w64-mingw32-tcc
i386-win32-tcc
x86_64-w64-mingw32-tcc
x86_64-win32-tcc
arm-wince-mingw32ce-tcc
arm-win32-tcc
Replacing a *-win32 directory names with a *-win names
because this names are based on the names of the tcc
x86_64-win32-tcc, i386-win32-tcc
Prevent libtcc1.a to be compiled with -fstack-protector-strong, so that
linking with tcc doesn't fail because symbol '__stack_chk_fail_local' is
not present in libtcc1.a. This is useful only if the CFLAGS passed from
the main Makefile contain this flag.
Not able to generate ELF files on NetBSD yet (lacks the note and crt1.o
is actually named crt0.o on NetBSD), but -run works with these extra
defines:
-D__lint__ -D"__symbolrename(x)=asm(#x)" -D__NetBSD__
The -D__lint__ is an ugly hack, TCC should be able to emulate GCC just
fine, but it seems TCC doesn't support __builtin_va_list yet?
typedef __builtin_va_list __va_list;
/usr/include/sys/ansi.h:72: error: ';' expected (got "__va_list")
This provides a simple implementation of alloca for ARM (and enables
the associated testcase). As tcc for ARM doesn't contain an assembler,
we'll have to resort using gcc for compiling it.
For program manipulating argv or arge as pointer with construct such as:
(while *argv++) {
do_something_with_argv;
}
it is necessary to have argv and arge inside a region. This patch create
regions argv and arge) if main is declared with those parameters.
Prior to this commit runtime library was compiled according to the host
because of the macro used to detec what architecture to choose. This
commit fixes this by using the TARGET_* macro instead.
- tccgen: error out for cast to void, as in
void foo(void) { return 1; }
This avoids an assertion failure in x86_64-gen.c, also.
also fix tests2/03_struct.c accordingly
- Error: "memory full" - be more specific
- Makefiles: remove circular dependencies, lookup tcctest.c from VPATH
- tcc.h: cleanup lib, include, crt and libgcc search paths"
avoid duplication or trailing slashes with no CONFIG_MULTIARCHDIR
(as from 9382d6f1a0)
- tcc.h: remove ";{B}" from PE search path
in ce5e12c2f9 James Lyon wrote:
"... I'm not sure this is the right way to fix this problem."
And the answer is: No, please. (copying libtcc1.a for tests instead)
- win32/build_tcc.bat: do not move away a versioned file
Variants __fixsfdi/__fixxfdi are not needed for now because
the value is converted to double always.
Also:
- remove __tcc_fpinit for unix as it seems redundant by the
__setfpucw call in the startup code
- avoid reference to s->runtime_main in cross compilers
- configure: fix --with-libgcc help
- tcctok.h: cleanup
- fix computation of absolute value (clearing the sign bit does not
since integers are encoded in 2's complement)
- test sign of integer in a more conventional way (binary and with the
high bit does not work for long long due to a bug in gtst)
- spacing in include
- Use runtime function for conversion
- Also initialize fp with tcc -run on windows
This fixes a bug where
double x = 1.0;
double y = 1.0000000000000001;
double z = x < y ? 0 : sqrt (x*x - y*y);
caused a bad sqrt because rounding precision for the x < y comparison
was different to the one used within the sqrt function.
This also fixes a bug where
printf("%d, %d", (int)pow(10, 2), (int)pow(10, 2));
would print
100, 99
Unrelated:
win32: document relative include & lib lookup
win32: normalize_slashes: do not mirror silly gcc behavior
This reverts part of commit 8a81f9e103
winapi: add missing WINAPI decl. for some functions
long double arguments require 16-byte alignment on the stack, which
requires adjustment when the the stack offset is not an evven number of
8-byte words.
I removed the XMM6/7 registers from the register list because they are not used
on Win64 however they are necessary for parameter passing on x86-64. I have now
restored them but not marked them with RC_FLOAT so they will not be used except
for parameter passing.
Modified tcctest.c so that it uses 'double' in place of 'long double'
with MinGW since this is what TCC does, and what Visual C++ does. Added
an option -norunsrc to tcc to allow argv[0] to be set independently of
the compiled source when using tcc -run, which allows tests that rely on
the value of argv[0] to work in out-of-tree builds.
Also added Makefile rules to automatically update out-of-tree build
Makefiles when in-tree Makefiles have changed.
On some architectures, ARM for instance, the data and instruction caches
are not coherent with each other. This is a problem for the -run feature
since instructions are written in memory, and are thus written in the
data cache first and then later flushed to the main memory. If the
instructions are executed before they are pushed out of the cache, then
the processor will fetch the old content from the memory and not the
newly generated code. The solution is to flush from the data cache all
the data in the memory region containing the instructions and to
invalidate the same region in the instruction cache.
- except for CONFIG_SYSROOT and CONFIG_TCCDIR
Strictly neccessary it is only for CONFIG_MULTIARCHDIR
because otherwise if it's in config.h it is impossible to
leave it undefined.
But it is also nicer not to use these definitions for
cross-compilers.
- Also:
lib/Makefile : include ../Makefile for CFLAGS
lib/libtcc1.c : fix an issue compiling tcc with tcc on x64
tests/Makefile:
- print-search-dirs when 'hello' fails
- split off hello-run
win32/include/_mingw.h:
- fix for compatibility with mingw headers
(While our headers in win32 are from mingw-64 and don't have
the problem)
tiny_libmaker:
- don't use "dangerous" mktemp
Should fix some warnings wrt. access out of array bounds.
tccelf.c: fix "static function unused" warning
x86_64-gen.c: fix "ctype.ref uninitialzed" warning and cleanup
tcc-win32.txt: remove obsolete limitation notes.
Also:
- fix "make tcc_p" (profiling version)
- remove old gcc flags:
-mpreferred-stack-boundary=2 -march=i386 -falign-functions=0
- remove test "hello" for Darwin (cannot compile to file)
* configure (fn_dirname): New.
Use it to ensure the creation of proper symlinks to Makefiles.
(config.mak): Define top_builddir and top_srcdir.
(CPPFLAGS): Be sure to find the headers.
* Makefile, lib/Makefile, tests/Makefile, tests2/Makefile: Adjust
to set VPATH properly.
Fix confusion between top_builddir and top_srcdir.
We were calling get_page() with t2 index which is not correct, since
get_page() operate on t1 indices. The bug is here from day-1, from
60f781c4 (first version of bounds checker) and show as a crash in
__bound_delete_region() at program exit:
$ ./tcc -B. -DTCC_TARGET_I386 -DCONFIG_MULTIARCHDIR=\"i386-linux-gnu\" -b -run -DONE_SOURCE \
./tcc.c -B. -DTCC_TARGET_I386 -DCONFIG_MULTIARCHDIR=\"i386-linux-gnu\" -run -DONE_SOURCE \
./tcc.c -B. -run tests/tcctest.c
(lot's of correct output from tcctest)
Runtime error: dereferencing invalid pointer
at 0xa7c21cc4 __bound_delete_region()
by (nil) ???
Segmentation fault
The fix is simple - last page should be get through t1_end, like it is
done in __bound_new_region().
After this patch, tcc is being able to compile itself with -b, then
compile itself again and run tcctest with correct output. Tests follow.
At startup __bound_init() wants to mark malloc zone as invalid memory,
so that any access to memory on heap, not allocated through malloc be
invalid. Other pages are initialized as empty regions, access to which
is not treated as invalid by bounds-checking.
The problem is code incorrectly assumed that heap goes right after bss,
and that is not correct for two cases:
1) if we are running from `tcc -b -run`, program text data and bss
will be already in malloced memory, possibly in mmaped region
insead of heap, and marking memory as invalid from _end
will not cover heap and probably wrongly mark correct regions.
2) if address space randomization is turned on, again heap does not
start from _end, and we'll mark as invalid something else instead
of malloc area.
For example with the following diagnostic patch ...
diff --git a/tcc.c b/tcc.c
index 5dd5725..31c46e8 100644
--- a/tcc.c
+++ b/tcc.c
@@ -479,6 +479,8 @@ static int parse_args(TCCState *s, int argc, char **argv)
return optind;
}
+extern int _etext, _edata, _end;
+
int main(int argc, char **argv)
{
int i;
@@ -487,6 +489,18 @@ int main(int argc, char **argv)
int64_t start_time = 0;
const char *default_file = NULL;
+ void *brk;
+
+ brk = sbrk(0);
+
+ fprintf(stderr, "\n>>> TCC\n\n");
+ fprintf(stderr, "etext:\t%10p\n", &_etext);
+ fprintf(stderr, "edata:\t%10p\n", &_edata);
+ fprintf(stderr, "end:\t%10p\n", &_end);
+ fprintf(stderr, "brk:\t%10p\n", brk);
+ fprintf(stderr, "stack:\t%10p\n", &brk);
+
+ fprintf(stderr, "&errno: %p\n", &errno);
s = tcc_new();
output_type = TCC_OUTPUT_EXE;
diff --git a/tccrun.c b/tccrun.c
index 531f46a..25ed30a 100644
--- a/tccrun.c
+++ b/tccrun.c
@@ -91,6 +91,8 @@ LIBTCCAPI int tcc_run(TCCState *s1, int argc, char **argv)
int (*prog_main)(int, char **);
int ret;
+ fprintf(stderr, "\n\ntcc_run() ...\n\n");
+
if (tcc_relocate(s1, TCC_RELOCATE_AUTO) < 0)
return -1;
diff --git a/lib/bcheck.c b/lib/bcheck.c
index ea5b233..8b26a5f 100644
--- a/lib/bcheck.c
+++ b/lib/bcheck.c
@@ -296,6 +326,8 @@ static void mark_invalid(unsigned long addr, unsigned long size)
start = addr;
end = addr + size;
+ fprintf(stderr, "mark_invalid %10p - %10p\n", (void *)addr, (void *)end);
+
t2_start = (start + BOUND_T3_SIZE - 1) >> BOUND_T3_BITS;
if (end != 0)
t2_end = end >> BOUND_T3_BITS;
... Look how memory is laid out for `tcc -b -run ...`:
$ ./tcc -B. -b -DTCC_TARGET_I386 -DCONFIG_MULTIARCHDIR=\"i386-linux-gnu\" -run \
-DONE_SOURCE ./tcc.c -B. -c x.c
>>> TCC
etext: 0x8065477
edata: 0x8070220
end: 0x807a95c
brk: 0x807b000
stack: 0xaffff0f0
&errno: 0xa7e25688
tcc_run() ...
mark_invalid 0xfff80000 - (nil)
mark_invalid 0xa7c31d98 - 0xafc31d98
>>> TCC
etext: 0xa7c22767
edata: 0xa7c2759c
end: 0xa7c31d98
brk: 0x8211000
stack: 0xafffeff0
&errno: 0xa7e25688
Runtime error: dereferencing invalid pointer
./tccpp.c:1953: at 0xa7beebdf parse_number() (included from ./libtcc.c, ./tcc.c)
./tccpp.c:3003: by 0xa7bf0708 next() (included from ./libtcc.c, ./tcc.c)
./tccgen.c:4465: by 0xa7bfe348 block() (included from ./libtcc.c, ./tcc.c)
./tccgen.c:4440: by 0xa7bfe212 block() (included from ./libtcc.c, ./tcc.c)
./tccgen.c:5529: by 0xa7c01929 gen_function() (included from ./libtcc.c, ./tcc.c)
./tccgen.c:5767: by 0xa7c02602 decl0() (included from ./libtcc.c, ./tcc.c)
The second mark_invalid goes right after in-memory-compiled program's
_end, and oops, that's not where malloc zone is (starts from brk), and oops
again, mark_invalid covers e.g. errno. Then compiled tcc is crasshing by
bcheck on errno access:
1776 static void parse_number(const char *p)
1777 {
1778 int b, t, shift, frac_bits, s, exp_val, ch;
...
1951 *q = '\0';
1952 t = toup(ch);
1953 errno = 0;
The solution here is to use sbrk(0) as approximation for the program
break start instead of &_end:
- if we are a separately compiled program, __bound_init() runs early,
and sbrk(0) should be equal or very near to start_brk (in case other
constructors malloc something), or
- if we are running from under `tcc -b -run`, sbrk(0) will return
start of heap portion which is under this program control, and not
mark as invalid earlier allocated memory.
With this patch `tcc -b -run tcc.c ...` succeeds compiling above
small-test program (diagnostic patch is still applied too):
$ ./tcc -B. -b -DTCC_TARGET_I386 -DCONFIG_MULTIARCHDIR=\"i386-linux-gnu\" -run \
-DONE_SOURCE ./tcc.c -B. -c x.c
>>> TCC
etext: 0x8065477
edata: 0x8070220
end: 0x807a95c
brk: 0x807b000
stack: 0xaffff0f0
&errno: 0xa7e25688
tcc_run() ...
mark_invalid 0xfff80000 - (nil)
mark_invalid 0x8211000 - 0x10211000
>>> TCC
etext: 0xa7c22777
edata: 0xa7c275ac
end: 0xa7c31da8
brk: 0x8211000
stack: 0xafffeff0
&errno: 0xa7e25688
(completes ok)
but running `tcc -b -run tcc.c -run tests/tcctest.c` sigsegv's - that's
the plot for the next patch.
On i386 and gcc-4.7 I found that __bound_local_new was miscompiled -
look:
#ifdef __i386__
/* return the frame pointer of the caller */
#define GET_CALLER_FP(fp)\
{\
unsigned long *fp1;\
__asm__ __volatile__ ("movl %%ebp,%0" :"=g" (fp1));\
fp = fp1[0];\
}
#endif
/* called when entering a function to add all the local regions */
void FASTCALL __bound_local_new(void *p1)
{
unsigned long addr, size, fp, *p = p1;
GET_CALLER_FP(fp);
for(;;) {
addr = p[0];
if (addr == 0)
break;
addr += fp;
size = p[1];
p += 2;
__bound_new_region((void *)addr, size);
}
}
__bound_local_new:
.LFB40:
.cfi_startproc
pushl %esi
.cfi_def_cfa_offset 8
.cfi_offset 6, -8
pushl %ebx
.cfi_def_cfa_offset 12
.cfi_offset 3, -12
subl $8, %esp // NOTE prologue does not touch %ebp
.cfi_def_cfa_offset 20
#APP
# 235 "lib/bcheck.c" 1
movl %ebp,%edx // %ebp -> fp1
# 0 "" 2
#NO_APP
movl (%edx), %esi // fp1[0] -> fp
movl (%eax), %edx
movl %eax, %ebx
testl %edx, %edx
je .L167
.p2align 2,,3
.L173:
movl 4(%ebx), %eax
addl $8, %ebx
movl %eax, 4(%esp)
addl %esi, %edx
movl %edx, (%esp)
call __bound_new_region
movl (%ebx), %edx
testl %edx, %edx
jne .L173
.L167:
addl $8, %esp
.cfi_def_cfa_offset 12
popl %ebx
.cfi_restore 3
.cfi_def_cfa_offset 8
popl %esi
.cfi_restore 6
.cfi_def_cfa_offset 4
ret
here GET_CALLER_FP() assumed that its using function setups it's stack
frame, i.e. first save, then set %ebp to stack frame start, and then it
has to do perform two lookups: 1) to get current stack frame through
%ebp, and 2) get caller stack frame through (%ebp).
And here is the problem: gcc decided not to setup %ebp for
__bound_local_new and in such case GET_CALLER_FP actually becomes
GET_CALLER_CALLER_FP and oops, wrong regions are registered in bcheck
tables...
The solution is to stop using hand written assembly and rely on gcc's
__builtin_frame_address(1) to get callers frame stack(*). I think for the
builtin gcc should generate correct code, independent of whether it
decides or not to omit frame pointer in using function - it knows it.
(*) judging by gcc history, __builtin_frame_address was there almost
from the beginning - at least it is present in 1992 as seen from the
following commit:
http://gcc.gnu.org/git/?p=gcc.git;a=commit;h=be07f7bdbac76d87d3006c89855491504d5d6202
so we can rely on it being supported by all versions of gcc.
In my environment the assembly of __bound_local_new changes as follows:
diff --git a/bcheck0.s b/bcheck1.s
index 4c02a5f..ef68918 100644
--- a/bcheck0.s
+++ b/bcheck1.s
@@ -1409,20 +1409,17 @@ __bound_init:
__bound_local_new:
.LFB40:
.cfi_startproc
- pushl %esi
+ pushl %ebp // NOTE prologue saves %ebp ...
.cfi_def_cfa_offset 8
- .cfi_offset 6, -8
+ .cfi_offset 5, -8
+ movl %esp, %ebp // ... and reset it to local stack frame
+ .cfi_def_cfa_register 5
+ pushl %esi
pushl %ebx
- .cfi_def_cfa_offset 12
- .cfi_offset 3, -12
subl $8, %esp
- .cfi_def_cfa_offset 20
-#APP
-# 235 "lib/bcheck.c" 1
- movl %ebp,%edx
-# 0 "" 2
-#NO_APP
- movl (%edx), %esi
+ .cfi_offset 6, -12
+ .cfi_offset 3, -16
+ movl 0(%ebp), %esi // stkframe -> stkframe.parent -> fp
movl (%eax), %edx
movl %eax, %ebx
testl %edx, %edx
@@ -1440,13 +1437,13 @@ __bound_local_new:
jne .L173
.L167:
addl $8, %esp
- .cfi_def_cfa_offset 12
popl %ebx
.cfi_restore 3
- .cfi_def_cfa_offset 8
popl %esi
.cfi_restore 6
- .cfi_def_cfa_offset 4
+ popl %ebp
+ .cfi_restore 5
+ .cfi_def_cfa 4, 4
ret
.cfi_endproc
i.e. now it compiles correctly.
Though I do not have x86_64 to test, my guess is that
__builtin_frame_address(1) should work there too. If not - please revert
only x86_64 part of the patch. Thanks.
Cc: Michael Matz <matz@suse.de>
On i386 and gcc-4.7 I found that libc_malloc was miscompiled - look:
static void *libc_malloc(size_t size)
{
void *ptr;
restore_malloc_hooks(); // __malloc_hook = saved_malloc_hook
ptr = malloc(size);
install_malloc_hooks(); // saved_malloc_hook = __malloc_hook, __malloc_hook = __bound_malloc
return ptr;
}
.type libc_malloc, @function
libc_malloc:
.LFB56:
.cfi_startproc
pushl %edx
.cfi_def_cfa_offset 8
movl %eax, (%esp)
call malloc
movl $__bound_malloc, __malloc_hook
movl $__bound_free, __free_hook
movl $__bound_realloc, __realloc_hook
movl $__bound_memalign, __memalign_hook
popl %ecx
.cfi_def_cfa_offset 4
ret
Here gcc inlined both restore_malloc_hooks() and install_malloc_hooks()
and decided that
saved_malloc_hook -> __malloc_hook -> saved_malloc_hook
stores are not needed and could be ommitted. Only it did not know
__molloc_hook affects malloc()...
So add compiler barrier to both install and restore hooks functions and
be done with it - the code is now ok:
diff --git a/bcheck0.s b/bcheck1.s
index 5f50293..4c02a5f 100644
--- a/bcheck0.s
+++ b/bcheck1.s
@@ -42,8 +42,24 @@ libc_malloc:
.cfi_startproc
pushl %edx
.cfi_def_cfa_offset 8
+ movl saved_malloc_hook, %edx
+ movl %edx, __malloc_hook
+ movl saved_free_hook, %edx
+ movl %edx, __free_hook
+ movl saved_realloc_hook, %edx
+ movl %edx, __realloc_hook
+ movl saved_memalign_hook, %edx
+ movl %edx, __memalign_hook
movl %eax, (%esp)
call malloc
+ movl __malloc_hook, %edx
+ movl %edx, saved_malloc_hook
+ movl __free_hook, %edx
+ movl %edx, saved_free_hook
+ movl __realloc_hook, %edx
+ movl %edx, saved_realloc_hook
+ movl __memalign_hook, %edx
+ movl %edx, saved_memalign_hook
movl $__bound_malloc, __malloc_hook
movl $__bound_free, __free_hook
movl $__bound_realloc, __realloc_hook
For barrier I use
__asm__ __volatile__ ("": : : "memory")
which is used as compiler barrier by Linux kernel, and mentioned in gcc
docs and in wikipedia [1].
Without this patch any program compiled with tcc -b crashes in startup
because of infinite recursion in libc_malloc.
[1] http://en.wikipedia.org/wiki/Memory_ordering#Compiler_memory_barrier
Other tests still have issues, currently with weak linking.
One of the primary stumbling blocks on OSX is the lack of support for
mach-o binaries. Therefore all tcc usage on OSX has to be limited to elf
binaries, presumably produced by tcc itself.
Therefore I had to enable building of tiny_libmaker for OSX. Then changed
the make to use tcc and tiny_libmaker to compile the tcclib1.
In order to compile the tests, specifically the parts that use weak linking,
I have had to define MACOSX_DEPLOYMENT_TARGET to 10.2, which seems like a
hack, but extensive searching seems to indicate that this is the only way
to make apple gcc allow weak linking. Using any other value, bigger or smaller
breaks weak linking.
Also added _ANSI_SOURCE define required by some OSX headers, and some cosmetic
gitignore changes. I believe these changes should not impact other platforms.
to the appropriate CFLAGS. In addition, memory hooks are very different
on OSX, so build of bcheck.c had to be disabled for now.
Change of the CFLAGS does affect builds on other platforms, and this needs
to be tested.
- add __builtin_va_arg_types to check how arguments were passed
- move most code of stdarg into libtcc1.c
- remove __builtin_malloc and __builtin_free
- add a test case based on the bug report
(http://www.mail-archive.com/tinycc-devel@nongnu.org/msg03036.html)
(Because GNU's alloca.h unconditionally #undef's alloca)
Also, remove gcc specific sections in headers. and
instead change tests such that gcc does not use them.
