Use 2 level strategy to access packed bitfields cleanly:
1) Allow to override the original declaration type with
an auxilary "access type". This solves cases such as
struct {
...
unsigned f1:1;
};
by using VT_BYTE to access f1.
2) Allow byte-wise split accesses using two new functions
load/store_packed_bf. This solves any cases, also ones
such as
struct __attribute((packed)) _s {
unsigned x : 12;
unsigned char y : 7;
unsigned z : 28;
unsigned a: 3;
unsigned b: 3;
unsigned c: 3;
};
where for field 'z':
- VT_INT access from offset 2 would be unaligned
- VT_LLONG from offset 0 would go past the total
struct size (7)
and for field 'a' because it is in two bytes and
aligned access with VT_SHORT/INT is not possible.
Also, static bitfield initializers are stored byte-wise always.
Also, cleanup the struct_layout function a bit.
tcc.h:
* cleanup struct 'Sym'
* include some 'Attributes' into 'Sym'
* in turn get rid of VT_IM/EXPORT, VT_WEAK
* re-number VT_XXX flags
* replace some 'long' function args by 'int'
tccgen.c:
* refactor parse_btype()
- configure
* use aarch64 instead of arm64
- Makefile
* rename the custom include file to "config-extra.mak"
* Also avoid "rm -r /*" if $(tccdir) is empty
- pp/Makefile
* fix .expect generation with gcc
- tcc.h
* cleanup #defines for _MSC_VER
- tccgen.c:
* fix const-propagation for &,|
* fix anonymous named struct (ms-extension) and enable
-fms-extension by default
- i386-gen.c
* clear VT_DEFSIGN
- x86_64-gen.c/win64:
* fix passing structs in registers
* fix alloca (need to keep "func_scratch" below each alloca area on stack)
(This allows to compile a working gnu-make on win64)
- tccpp.c
* alternative approach to 37999a4fbf
This is to avoid some slowdown with ## token pasting.
* get_tok_str() : return <eof> for TOK_EOF
* -funsigned-char: apply to "string" literals as well
- tccpe/tools.c: -impdef: support both 32 and 64 bit dlls anyway
Simple implementation, I'm not even sure to respect C standart here,
but it should work with most use case.
This add an case in unary(), and generate TokString depending of _Generic
controlling exression, use begin_macro to "push"
the generated TokString, then call unary() again before exiting the switch
so the just add token are reevaluate again.
This reverts commit d4fe9aba3f.
I was confused by the fact that string literals aren't writable.
Nevertheless the type isn't const. As extension in GCC it's const
with -Wwrite-string, which is exactly what we had before.
GCC also wonders in a comment if it's really a good idea to change
expression types based on warning flags (IMHO it's not), but let's
be compatible. So restore the state from before.
Don't make the standard mandated types of string literals
depends on warning options. Instead make them always const,
but limit the emission of the warning by that option.
Only warn if the struct has a non-zero size. You can't create objects
of zero-sized structs, but they can be used inside sizeof (e.g.
"sizeof (struct {int :0;})". The warning would always trigger for these,
but as no objects can be created no accesses can ever happen.
- configure:
- add --config-uClibc,-musl switch and suggest to use
it if uClibc/musl is detected
- make warning options magic clang compatible
- simplify (use $confvars instead of individual options)
- Revert "Remove some unused-parameter lint"
7443db0d5f
rather use -Wno-unused-parameter (or just not -Wextra)
- #ifdef functions that are unused on some targets
- tccgen.c: use PTR_SIZE==8 instead of (X86_64 || ARM64)
- tccpe.c: fix some warnings
- integrate dummy arm-asm better
For integer promotion with for example arithmetics or
expr_cond (x ? y : z), integral types need to be promoted
to signed if they fit.
According to latest standards, this also applies to bit-field
types taking into account their specific width.
In tcc, VT_BITFIELD set means width < original type width
Field-widths between 33 and 63 are promoted to signed long long
accordingly.
struct { unsigned long long ullb:35; } s = { 1 };
#define X (s.ullb - 2)
int main (void)
{
long long Y = X;
printf("%d %016llx %016llx\n", X < 0, -X, -Y);
return 0;
}
Results:
GCC 4.7 : 0 0000000000000001 FFFFFFF800000001
MSVC : 1 0000000000000001 0000000000000001
TCC : 1 0000000000000001 0000000000000001
Also, gcc would promote long long bitfields of size < 32
to int as well. Example:
struct { unsigned long long x:20; } t = { 123 };
/* with gcc: */ printf("%d %d\n", t.x, 456);
/* with tcc: */ printf("%lld %d\n", t.x, 456);
bit_pos + bit_size > type_size * 8
must NEVER happen because the code generator can read/write
only the basic integral types.
Warn if tcc has to break GCC compatibility for that reason
and if -Wgcc-compat is given.
Example:
struct __attribute__((packed)) _s
{
unsigned int x : 12;
unsigned char y : 7;
unsigned int z : 28;
};
Expected (GCC) layout (sizeof struct = 6)
.xxxxxxxx.xxxxyyyy.yyyzzzzz.zzzzzzzz.zzzzzzzz.zzzzzzz0.
But we cannot read/write 'char y'from 2 bytes in memory.
So we have to adjust:
.xxxxxxxx.xxxx0000.yyyyyyyz.zzzzzzzz.zzzzzzzz.zzzzzzzz.zzz00000
Now 'int z' cannot be accessed from 5 bytes. So we arrive
at this (sizeof struct = 7):
.xxxxxxxx.xxxx0000.yyyyyyy0.zzzzzzzz.zzzzzzzz.zzzzzzzz.zzzz0000
Otherwise the bitfield load/store generator needs to be
changed to allow byte-wise accesses.
Also we may touch memory past the struct in some cases
currently. The patch adds a warning for that too.
0: 55 push %ebp
1: 89 e5 mov %esp,%ebp
3: 81 ec 04 00 00 00 sub $0x4,%esp
9: 90 nop
struct __attribute__((packed)) { unsigned x : 5; } b = {0} ;
a: 8b 45 ff mov -0x1(%ebp),%eax
d: 83 e0 e0 and $0xffffffe0,%eax
10: 89 45 ff mov %eax,-0x1(%ebp)
This touches -0x1 ... +0x3(%ebp), hence 3 bytes beyond
stack space. Since the data is not changed, nothing
else happens here.
* tccgen: re-allow long double constants for x87 cross
sizeof (long double) may be 12 or 16 depending on host platform
(i386/x86_64 on unix/windows).
Except that it's 8 if the host is on windows and not gcc
was used to compile tcc.
* win64: fix builtin_va_start after VT_REF removal
See also a8b83ce43a
* tcctest.c: remove outdated limitation for ll-bitfield test
It always worked, there is no reason why it should not work
in future.
* libtcc1.c: exclude long double conversion on ARM
* Makefile: remove CFLAGS from link recipes
* lib/Makefile: use target DEFINES as passed from main Makefile
* lib/armflush.c lib/va_list.c: factor out from libtcc1.c
* arm-gen.c: disable "depreciated" warnings for now
'extern int i = 42;' at file scope (but not in function scope!) is
allowed and is a proper definition, even though questionable style;
some compilers warn about this.
See the added testcase. When one used designators like .a.x to initialize
sub-members of members, and didn't then initialize all of them the
required zero-initialization of the other sub-members wasn't done.
The fix also enables tiny code cleanups.
See testcase. If an enum has only positive values, fits N bits,
and is placed in a N-bit bit-field that bit-fields must be treated
as unsigned, not signed.
This invalid function definition:
int f()[] {}
was tried to be handled but there was no testcase if it actually worked.
This fixes it and adds a TCC only testcase.
introduce common_section (SHN_COMMON), factorize some handling
in decl_initializer_alloc, add section_add and use it to factorize
some code that allocates stuff in sections (at the same time also fixing
harmless bugs re section alignment), use init_putv to emit float consts
into .data from gv() (fixing an XXX).
factor code a bit for transforming tokens into SValues. This revealed
a bug in TOK_GET (see testcase), which happened to be harmless before.
So fix that as well.
The canonical way to describe a local variable that actually holds
the address of an lvalue is VT_LLOCAL. Remove the last user of VT_REF,
and handling of it, thereby freeing a flag for SValue.r.
VT_LLOCAL is a flag on .r, not on type.t. Fixing this requires
minor surgery for compound literals which accidentally happened
to be subsumed by the bogus test.
the second argument can be an arbitrary expression (including
side-effects), not just a constant. This removes the last user
of expr_lor_const and hence also that function (and expr_land_const).
Also the argument to __builtin_constant_p can be only a non-comma
expression (like all functions arguments).
Our code generation assumes that it can load/store with the
bit-fields base type, so bit_pos/bit_size must be in range for this.
We could change the fields type or adjust offset/bit_pos; we do the
latter.
Checked the lcc testsuite for bitfield stuff (in cq.c and fields.c),
fixed one more error in initializing unnamed members (which have
to be skipped), removed the TODO.
- configure/Makefiles: minor adjustments
- build-tcc.bat: add -static to gcc options
(avoids libgcc_s*.dll dependency with some mingw versions)
- tccpe.c/tcctools.c: eliminate MAX_PATH
(not available for cross compilers)
- tccasm.c: use uint64_t/strtoull in unary()
(unsigned long sometimes is only uint32_t, as always on windows)
- tccgen.c: Revert (f077d16c) "tccgen: gen_cast: cast FLOAT to DOUBLE"
Was a rather experimental, tentative commit, not really necessary
and somewhat ugly too.
- cleanup recent osx support:
- Makefile/libtcc.c: cleanup copy&paste code
- tccpp.c: restore deleted function
Also, retain storage qualifiers in type_decl, in particular
also for function pointers. This allows to get rid of this
very early hack in decl()
type.t |= (btype.t & VT_STATIC); /* Retain "static". */
which was to fix the case of
int main() { static int (*foo)(); ...
Also:
- missing __declspec(dllimport) is an error now
- except if the symbol is "_imp__symbol"
- demonstrate export/import of data in the dll example (while
'extern' isn't strictly required with dllimport anymore)
- new function 'patch_storage()' replaces 'weaken_symbol()'
and 'apply_visibility()'
- new function 'update_storage()' applies storage attributes
to Elf symbols.
- put_extern_sym/2 accepts new pseudo section SECTION_COMMON
- add -Wl,-export-all-symbols as alias for -rdynamic
- add -Wl,-subsystem=windows for mingw compatibility
- redefinition of 'sym' error for initialized global data
Forgot about it. It allows to compile several
sources (and other .o's) to one single .o file;
tcc -r -o all.o f1.c f2.c f3.S o4.o ...
Also:
- option -fold-struct-init-code removed, no effect anymore
- (tcc_)set_environment() moved to tcc.c
- win32/lib/(win)crt1 minor fix & add dependency
- debug line output for asm (tcc -c -g xxx.S) enabled
- configure/Makefiles: x86-64 -> x86_64 changes
- README: cleanup
- tccgen.c/tcc.h: allow function declaration after use:
int f() { return g(); }
int g() { return 1; }
may be a warning but not an error
see also 76cb1144ef
- tccgen.c: redundant code related to inline functions removed
(functions used anywhere have sym->c set automatically)
- tccgen.c: make 32bit llop non-equal test portable
(probably not on C67)
- dynarray_add: change prototype to possibly avoid aliasing
problems or at least warnings
- lib/alloca*.S: ".section .note.GNU-stack,"",%progbits" removed
(has no effect)
- tccpe: set SizeOfCode field (for correct upx decompression)
- libtcc.c: fixed alternative -run invocation
tcc "-run -lxxx ..." file.c
(meant to load the library after file).
Also supported now:
tcc files ... options ... -run @ arguments ...
Some code in gen_opl was depending on a gvtst label
which in nocode_wanted mode is not set.
This was causing vstack leaks and crashes with for example
long long ll;
if (0)
return ll - 10 < 0;
Also:
- on windows i386 and x86-64, structures of size <= 8 are
NOT returned in registers if size is not one of 1,2,4,8.
- cleanup: put all tv-push/pop/swap/rot into one place
Some more subtle issues with code suppression:
- outputting asms but not their operand setup is broken
- but global asms must always be output
- statement expressions are transparent to code suppression
- vtop can't be transformed from VT_CMP/VT_JMP when nocode_wanted
Also remove .exe files from tests2 if they don't fail.
Restore ebx from *ebp because alloca might change esp.
Also disable USE_EBX for upcoming release.
Actually the benefit is less than one would expect, it
appears that tcc can't do much with more than 3 registers
except with extensive use of long longs where the disassembly
looks much prettier (and shorter also).
Also: tccgen/expr_cond() : fix wrong gv/save_regs order
Also ...
tcctest.c:
- exclude stuff that gcc doesn't compile on windows.
libtcc.c/tccpp.c:
- use unsigned for memory sizes to avoid printf format warnings
- use "file:line: message" to make IDE error parsers happy.
tccgen.c: fix typo
