search for: _atomic

There's a discussion over on cfe-commits about how future-proof to make the C1x/C++11 atomic ABI. (http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20111010/047647.html) One argument is that, because C ABI changes are painful, and processors may introduce larger atomic operations in the future, we should try to design the atomics implementation in such a way that it can take

I have started working on an implementation of atomic_ref. Implementing this requires performing atomic operations on arbitrary references. The behavior is undefined if a reference is provided that is not aligned per the public export required_alignment. What assumptions do the __c11_atomic builtins make about destination argument alignment, format, size etc.? Is it required that the destination argument be annotated as _Atomic like the corresponding standard c11 functions require? The following code in libcxx/include/config implies that the c11 atomic builtins should be substituted...

...ns, which clang lowers directly to atomic IR instructions. Then, the llvm atomic IR instructions themselves can sometimes emit libcalls to __sync_* library functions (which are basically undocumented, and users are often responsible for implementing themselves if they need it). There's the new __atomic_* builtins, which clang will, depending on size and alignment and target, lower either to a libcall to a "standardized-by-GCC <https://gcc.gnu.org/wiki/Atomic/GCCMM/LIbrary>" __atomic_* library function (implemented by libatomic), or, to the atomic IR instructions. (Also covered by...

...t.hpp:117:9: error: cannot compile this atomic library call yet CV_XADD(refcount, 1); ^~~~~~~~~~~~~~~~~~~~ /home/silky/VecProject/opencv/OpenCVInstall/arm/include/opencv2/core/operations.hpp:61:38: note: expanded from macro 'CV_XADD' #define CV_XADD(addr, delta) __c11_atomic_fetch_add((_Atomic(int)*)(addr), (delta), __ATOMIC_SEQ_CST) Could someone please suggest what I am missing here, or what the error indicates? Thank you all. -- View this message in context: http://llvm.1065342.n5.nabble.com/Running-cross-compiled-binaries-for-ARM-on-gem5-tp55767p56023.html Se...

...tomic IR instructions. Then, the llvm atomic IR instructions > themselves can sometimes emit libcalls to __sync_* library > functions (which are basically undocumented, and users are often > responsible for implementing themselves if they need it). > 2. There's the new __atomic_* builtins, which clang will, depending > on size and alignment and target, lower either to a libcall to a > "standardized-by-GCC > <https://gcc.gnu.org/wiki/Atomic/GCCMM/LIbrary>" __atomic_* > library function (implemented by libatomic), or, to the atomi...

...tructions. Then, the llvm atomic IR > instructions themselves can sometimes emit libcalls to __sync_* > library functions (which are basically undocumented, and users > are often responsible for implementing themselves if they need > it). > 2. There's the new __atomic_* builtins, which clang will, > depending on size and alignment and target, lower either to a > libcall to a " standardized-by-GCC " __atomic_* library function > (implemented by libatomic), or, to the atomic IR instructions. > (Also covered by the same code is...

Quoting Tim Northover <t.p.northover at gmail.com>: > On 24 April 2015 at 13:53, Tyler Denniston <tyler at csail.mit.edu> wrote: >> I'm wondering how I can create an atomic load and add instruction for >> floating point values. If I use IRBuilder::CreateAtomicRMW() I get the >> error message: "atomicrmw operand must have integer type". > >

...this atomic library call yet > CV_XADD(refcount, 1); > ^~~~~~~~~~~~~~~~~~~~ > > /home/silky/VecProject/opencv/OpenCVInstall/arm/include/opencv2/core/operations.hpp:61:38: > note: expanded from macro 'CV_XADD' > #define CV_XADD(addr, delta) > __c11_atomic_fetch_add((_Atomic(int)*)(addr), (delta), __ATOMIC_SEQ_CST) > This is odd. This atomic is implemented in CGAtomic.cpp, but it's being lowered as a library call because "UseLibcall" is true: bool UseLibcall = (Size != Align || getContext().toBits(sizeChars) &g...

...t;\n"; > diff --git a/lib/connect.c b/lib/connect.c > index b889f80..4e3141f 100644 > --- a/lib/connect.c > +++ b/lib/internal.h > @@ -80,7 +80,17 @@ struct nbd_handle { > /* Linked list of close callbacks. */ > struct close_callback *close_callbacks; > > - _Atomic enum state state; /* State machine. */ > + /* State machine. > + * > + * The actual current state is ‘next_state’. ‘state’ is updated > + * before we release the lock. > + * > + * Note don't access these fields directly, use the SET_NEXT_STATE > + * macro...

On Sun, 2016-01-10 at 13:56 +0200, Michael S. Tsirkin wrote: > SMP-only barriers were missing in checkpatch.pl > > Refactor code slightly to make adding more variants easier. [] > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl [] > @@ -5116,7 +5116,25 @@ sub process { > ? } > ? } > ?# check for memory barriers without a comment. > - if ($line =~

On Sun, 2016-01-10 at 13:56 +0200, Michael S. Tsirkin wrote: > SMP-only barriers were missing in checkpatch.pl > > Refactor code slightly to make adding more variants easier. [] > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl [] > @@ -5116,7 +5116,25 @@ sub process { > ? } > ? } > ?# check for memory barriers without a comment. > - if ($line =~

.../lib/connect.c > > index b889f80..4e3141f 100644 > > --- a/lib/connect.c > > > +++ b/lib/internal.h > > @@ -80,7 +80,17 @@ struct nbd_handle { > > /* Linked list of close callbacks. */ > > struct close_callback *close_callbacks; > > > > - _Atomic enum state state; /* State machine. */ > > + /* State machine. > > + * > > + * The actual current state is ‘next_state’. ‘state’ is updated > > + * before we release the lock. > > + * > > + * Note don't access these fields directly, use the SE...

...= -1; h->export_name = strdup (""); diff --git a/lib/internal.h b/lib/internal.h index 7290247..1bef1c2 100644 --- a/lib/internal.h +++ b/lib/internal.h @@ -80,7 +80,17 @@ struct nbd_handle { /* Linked list of close callbacks. */ struct close_callback *close_callbacks; - _Atomic enum state state; /* State machine. */ + /* State machine. + * + * The actual current state is ‘next_state’. ‘state’ is updated + * before we release the lock. + * + * Note don't access these fields directly, use the SET_NEXT_STATE + * macro in generator/states* code, or the s...

...think this more of a front-end issue than a compile-rt issue, but I’m also copying the llvm-dev list In compiler-rt the file lib/builtins/atomic.c seems to rely on determining at compile time if an atomic operation of size 1, 2, 4, or 8 is always lock free. For example, in the implementation of __atomic_load_8() we have something like this after macro expansion: void __atomic_load_8(…) { If (__c11_atomic_is_lock_free(8)) return __c11_atomic_load_8(..) /* otherwise lock-based implementation */ } Let’s say a target supports lock-free atomics for 8-byte objects. Then the front-end will lower...

...= -1; h->export_name = strdup (""); diff --git a/lib/internal.h b/lib/internal.h index 61ddbde..503bf34 100644 --- a/lib/internal.h +++ b/lib/internal.h @@ -80,7 +80,17 @@ struct nbd_handle { /* Linked list of close callbacks. */ struct close_callback *close_callbacks; - _Atomic enum state state; /* State machine. */ + /* State machine. + * + * The actual current state is ‘state’. ‘public_state’ is updated + * before we release the lock. + * + * Note don't access these fields directly, use the SET_NEXT_STATE + * macro in generator/states* code, or the...

...call yet > CV_XADD(refcount, 1); > ^~~~~~~~~~~~~~~~~~~~ > /home/silky/VecProject/opencv/OpenCVInstall/arm/include/opencv2/core/operations.hpp:61:38: > note: expanded from macro 'CV_XADD' > #define CV_XADD(addr, delta) > __c11_atomic_fetch_add((_Atomic(int)*)(addr), (delta), > __ATOMIC_SEQ_CST) > > > This is odd. This atomic is implemented in CGAtomic.cpp, but it's > being lowered as a library call because "UseLibcall" is true: > > bool UseLibcall = (Size != Align || >...

...not to have to > prefix it with smp_ before using it. > > my $smp_barriers = qr{ > smp_store_release| > smp_load_acquire| > smp_store_mb| > smp_read_barrier_depends That's missing (?:barriers) too. btw: shouldn't this also have smp_mb__(?:before|after)_atomic ?

...ickets.head) == want) { >> + head = READ_ONCE(lock->tickets.head); >> + if (__tickets_equal(head, want)) { >> add_stats(TAKEN_SLOW_PICKUP, 1); >> goto out; > > This is off-topic, but with or without this change perhaps it makes sense > to add smp_mb__after_atomic(). It is nop on x86, just to make this code > more understandable for those (for me ;) who can never remember even the > x86 rules. > Hope you meant it for add_stat. yes smp_mb__after_atomic() would be harmless barrier() in x86. Did not add this V5 as yoiu though but this made me look a...

...ickets.head) == want) { >> + head = READ_ONCE(lock->tickets.head); >> + if (__tickets_equal(head, want)) { >> add_stats(TAKEN_SLOW_PICKUP, 1); >> goto out; > > This is off-topic, but with or without this change perhaps it makes sense > to add smp_mb__after_atomic(). It is nop on x86, just to make this code > more understandable for those (for me ;) who can never remember even the > x86 rules. > Hope you meant it for add_stat. yes smp_mb__after_atomic() would be harmless barrier() in x86. Did not add this V5 as yoiu though but this made me look a...

Hi Silky, If I got correctly, you seem to be trying to run a bare-metal image on your model, but you compile with linux-gnueabi GCC. I don't know if that will make a difference, but I'd try to use none-eabi GCC toolchain and set the -target armv7a-none-eabi just in case. On 10 March 2013 00:26, Silky Arora <silkyar at umich.edu> wrote: > Most of the search results talk about