The only reason why it is tough for us to use nano malloc
is because of the small shortcoming where nano_malloc()
splits a bigger chunk from the free list into two pieces
while handing back the second one (the tail) to the user.
This is error prone and especially bad for smaller heaps,
where nano malloc is supposed to be superior. The normal
malloc doesn't have this issue and we need to use it even
though it costs us ~2k bytes compared to nano-malloc.
The problem arise especially after giving back _every_
malloced memory to the heap and then starting to exercise
the heap again by allocating something small. This small
item might split the whole heap in two equally big parts
depending on how the heap has been exercised before.
I have uploaded the smallest possible application
(only tested on ST and Nordic devices) to show the issue
while the real customer applications are far more complicated:
https://drive.google.com/file/d/1kfSC2KOm3Os3mI7EBd-U0j63qVs8xMbt/view?usp=sharing
The application works like the following pseudo code,
where we assume a heap of 100 bytes
(I haven't taken padding and other nitty and gritty
details into account. Everything to simplify understanding):
void *ptr = malloc(52); // We get 52 bytes and we have
// 48 bytes to use.
free(ptr); // Hand back the 52 bytes to nano_malloc
// This is the magic line that shows the issue of
// nano_malloc
ptr = malloc(1); // Nano malloc will split the 52 bytes
// in the free list and hand you a pointer
// somewhere in the
// middle of the heap.
ptr2 = malloc(52); // Out of memory...
I have done a fix which hands back the first part of the
splitted chunk. Once this is fixed we obviously
have the 1 byte placed in position 0 of the heap instead
of somewhere in the middle.
However, this won't let us malloc 52 new bytes even though
we potentially have 99 bytes left to use in the heap. The
reason is that when we try to do the allocation,
nano-malloc looks into the free list and sees a 51 byte
chunk to be used.
This is not big enough so nano-malloc decides to call
sbrk for _another_ 52 bytes which is not possible since
there is only 48 bytes left to ask for.
The solution for this problem is to check if the last
item in the free list is adjacent to sbrk(0). If it is,
as it is in this case, we can just ask sbrk for the
remainder of what is needed. In this case 1 byte.
NB! I have only tested the solution on our ST device.
Use the more official fesetenv(FE_DFL_ENV) from _dll_crt0, thus
allowing to drop the _feinitialise declaration from fenv.h.
Provide a no-op _feinitialise in Cygwin as exportable symbol for really
old applications when _feinitialise was called from mainCRTStartup in
crt0.o.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Drop the Cygwin-specific fenv.cc and fenv.h file and use the equivalent
newlib functionality now, so we have at least one example of a user for
this new mechanism.
fenv.c: allow _feinitialise to be called from Cygwin startup code
fenv.h: add declarations for fegetprec and fesetprec for Cygwin only.
Fix a comment.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Add a directory libc/machine/shared_x86 to share header files
between ix86 and x86_64 architectures.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
So far the build mechanism in newlib only allowed to either define
machine-specific headers, or headers shared between all machines.
In some cases, architectures are sufficiently alike to share header
files between them, but not with other architectures. A good example
is ix86 vs. x86_64, which share certain traits with each other, but
not with other architectures.
Introduce a new configure variable called "shared_machine_dir". This
dir can then be used for headers shared between architectures.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Without this, for a bare-iron/simulator target such as cris-elf,
you'll see, at newlib build time:
/x/gccobj/./gcc/xgcc -B/x/gccobj/./gcc/ <many options elided> -c -o lib_a-aligned_alloc.o \
`test -f 'aligned_alloc.c' || echo '/y/newlib/libc/stdlib/'`aligned_alloc.c
/y/newlib/libc/stdlib/aligned_alloc.c: In function 'aligned_alloc':
/y/newlib/libc/stdlib/aligned_alloc.c:35:10: warning: implicit declaration of function \
'_memalign_r' [-Wimplicit-function-declaration]
35 | return _memalign_r (_REENT, align, size);
| ^~~~~~~~~~~
The revert-part of the revert-and-fix commit, b99887c428 a.k.a.
"Revert previous change to sys/stat.h and fix cris libgloss",
apparently intending to revert f75aa67851 a.k.a. "Fix regression in
cris-elf caused by sys/stat.h change" and fix it in another way,
wasn't complete. Although the fix-part added the prerequisite "#undef
st_atime" (et al) to gensyscalls, the revert-part didn't revert the
"&& !defined(__cris__)" in sys/stat.h, stopping st_atime (et al) from
being defined.
The effect of the unreverted change is that accessing the struct stat
compatibility member names "st_atime" (et al) as in "struct stat
mystat; mystat.st_atime;" yields errors, observable for example when
building libgfortran in gcc:
/x/gcc/libgfortran/intrinsics/stat.c:114:42: error: 'struct stat' has \
no member named 'st_atime'; did you mean 'st_atim'?
114 | sarray->base_addr[8 * stride] = sb.st_atime;
| ^~~~~~~~
| st_atim
(etc.)
Trivially fixed by completing the reversion, removing the "&&
!defined(__cris__)" in sys/stat.h.
Beware: the net effect of the earlier related change to struct stat in
sys/stat.h, leading up to the fix, *does* change its definition as a
type. Thankfully, replacing members like "time_t st_atime; long
st_spare1;" by "struct timespec st_atim;", ditto st_mtim and st_ctim,
is layout-compatible. To wit, that change is "binary compatible".
Incidentally, related to the simulator / Linux ABI, there's a
transitional stage (see gensyscalls), reloading between "struct stat"
(sys/stat.h) and "struct new_stat" (kernel/simulator) as necessary.
Tested by a cris-elf gcc build (including libgfortran).
This Patch removes Soft Float code from MIPS.
Instead It adds the soft float code from RISCV
The code came from FreeBSD and assumes the FreeBSD softfp
implementation not the one with GCC. That was an overlooked and
fixed in the other fenv code already.
Signed-off-by: Eshan Dhawan <eshandhawan51@gmail.com>
Change the prototypes to be in line with POSIX/glibc. This may fix
issues with new warnings produced by GCC 11.
Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>
Add the POSIX header file <poll.h> which is used by the GCC 11 Ada
runtime support.
Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>
The Cortex-R52 processor is an Armv8-R processor with a NEON unit. This
fix prevents conflicting architecture profiles A/R errors issued by the
linker.
Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>
This patch fixes the error found by Paul Zimmermann (see
https://homepages.loria.fr/PZimmermann/papers/#accuracy) regarding x
close to 1 and rather large y (specifically he found the case
powf(0x1.ffffeep-1,-0x1.000002p+27) which returns +Inf instead of the
correct value). We found 2 more values for x which show the same faulty
behaviour, and all 3 are fixed with this patch. We have tested all
combinations for x in [+1.fffdfp-1, +1.00020p+0] and y in
[-1.000007p+27, -1.000002p+27] and [1.000002p+27,1.000007p+27].
The overflow check in mEMALIGn erroneously checks for INT_MAX,
albeit the input parameter is size_t. Fix this to check for
__SIZE_MAX__ instead. Also, it misses to check the req against
adding the alignment before calling mALLOc.
While at it, add out-of-bounds checks to pvALLOc, nano_memalign,
nano_valloc, and Cygwin's (unused) dlpvalloc.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
to rb parent pointers. Define RB_SWAP_CHILD to replace the child of a parent
with its twin, and use it in 4 places. Use RB_SET in rb_link_node to remove the
only linuxkpi reference to color, and then drop color- and parent-related
definitions that are defined and used only in rbtree.h.
This is intended to be entirely cosmetic, with no impact on program
behavior, and leave RB_PARENT and RB_SET_PARENT as the only ways to
read and write rb parent pointers.
Reviewed by: markj, kib
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D25264
the sibling of the root of the too-short tree is black and at least one of the
children of that sibling is red, either one or two rotations finish the
rebalancing. In the case when both of the children are red, the current
implementation uses two rotations where only one is necessary. This change
removes that extra rotation, and in that case also removes a needless
black-to-red-to-black recoloring.
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D25335
without using their interfaces, making them break when the representation
changes. Revert changes that eliminated the color field from rb-trees, leaving
everything as it was before.
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D25250
a bit of DIAGNOSTIC code that depends on it.
Reported by: rpokala, mjguzik
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D25204
field. Set the least significant bit in the pointer to the node from its parent
to indicate that the node is red. Have the tree rotation macros leave the
old-parent/new-child node red and the new-parent/old-child node black.
This change makes RB_LEFT and RB_RIGHT no longer assignable, and
RB_COLOR no longer defined. Any code that modifies the tree or
examines a node color would have to be modified after this change.
Reviewed by: markj
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D25105
where the pointer checked is provably never null. Restructure the surrounding
code just enough to make the non-nullness obvious.
Reviewed by: markj
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D25089
child is red or child is null. In the first case, RB_REMOVE_COLOR just changes
the child to black and returns. With this change, RB_REMOVE handles that case,
and drops the child argument to RB_REMOVE_COLOR, since that value is always
null.
RB_REMOVE_COLOR is changed to remove a couple of unneeded tests, and
to eliminate some deep indentation.
RB_ISRED is defined to combine a null check with a test for redness,
to replace that combination in several places.
Reviewed by: markj
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D25032
search to find the node to replace the one being removed, restructure to first
remove the replacement node and correct the parent pointers around it, and then
let the all-cases code at the end deal with the parent of the deleted node,
making it point to the replacement node. This removes one or two conditional
branches.
Reviewed by: markj
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D24845
Joel Sherrill
Ola Olsson
Mike Frysinger
Ties Stuij
Corinna Vinschen
David Macek
Jeff Johnston
Marcus Comstedt
Hans-Peter Nilsson
Eshan dhawan
Sebastian Huber
Paul Zimmermann
Fabian Schriever
Kito Cheng
Corinna Vinschen
Ivan Grokhotov
dougm