Implement fetch_<op>/fetch_and_<op>/exchange/compare-and-exchange
instructions for BPF. Specially, the following gcc intrinsics
are implemented.
__sync_fetch_and_add (32, 64)
__sync_fetch_and_sub (32, 64)
__sync_fetch_and_and (32, 64)
__sync_fetch_and_or (32, 64)
__sync_fetch_and_xor (32, 64)
__sync_lock_test_and_set (32, 64)
__sync_val_compare_and_swap (32, 64)
For __sync_fetch_and_sub, internally, it is implemented as
a negation followed by __sync_fetch_and_add.
For __sync_lock_test_and_set, despite its name, it actually
does an atomic exchange and return the old content.
https://gcc.gnu.org/onlinedocs/gcc-4.1.1/gcc/Atomic-Builtins.html
For intrinsics like __sync_{add,sub}_and_fetch and
__sync_bool_compare_and_swap, the compiler is able to generate
codes using __sync_fetch_and_{add,sub} and __sync_val_compare_and_swap.
Similar to xadd, atomic xadd, xor and xxor (atomic_<op>)
instructions are added for atomic operations which do not
have return values. LLVM will check the return value for
__sync_fetch_and_{add,and,or,xor}.
If the return value is used, instructions atomic_fetch_<op>
will be used. Otherwise, atomic_<op> instructions will be used.
All new instructions only support 64bit and 32bit with alu32 mode.
old xadd instruction still supports 32bit without alu32 mode.
For encoding, please take a look at test atomics_2.ll.
Differential Revision: https://reviews.llvm.org/D72184
This reverts commit 80a34ae311 with fixes.
Previously, since bots turning on EXPENSIVE_CHECKS are essentially turning on
MachineVerifierPass by default on X86 and the fact that
inline-asm-avx-v-constraint-32bit.ll and inline-asm-avx512vl-v-constraint-32bit.ll
are not expected to generate functioning machine code, this would go
down to `report_fatal_error` in MachineVerifierPass. Here passing
`-verify-machineinstrs=0` to make the intent explicit.
This reverts commit 80a34ae311 with fixes.
On bots llvm-clang-x86_64-expensive-checks-ubuntu and
llvm-clang-x86_64-expensive-checks-debian only,
llc returns 0 for these two tests unexpectedly. I tweaked the RUN line a little
bit in the hope that LIT is the culprit since this change is not in the
codepath these tests are testing.
llvm\test\CodeGen\X86\inline-asm-avx-v-constraint-32bit.ll
llvm\test\CodeGen\X86\inline-asm-avx512vl-v-constraint-32bit.ll
This reverts commit rGcd5b308b828e, rGcd5b308b828e, rG8cedf0e2994c.
There are issues to be investigated for polly bots and bots turning on
EXPENSIVE_CHECKS.
Summary:
This patch could be treated as a rebase of D33960. It also fixes PR35547.
A fix for `llvm/test/Other/close-stderr.ll` is proposed in D68164. Seems
the consensus is that the test is passing by chance and I'm not
sure how important it is for us. So it is removed like in D33960 for now.
The rest of the test fixes are just adding `--crash` flag to `not` tool.
** The reason it fixes PR35547 is
`exit` does cleanup including calling class destructor whereas `abort`
does not do any cleanup. In multithreading environment such as ThinLTO or JIT,
threads may share states which mostly are ManagedStatic<>. If faulting thread
tearing down a class when another thread is using it, there are chances of
memory corruption. This is bad 1. It will stop error reporting like pretty
stack printer; 2. The memory corruption is distracting and nondeterministic in
terms of error message, and corruption type (depending one the timing, it
could be double free, heap free after use, etc.).
Reviewers: rnk, chandlerc, zturner, sepavloff, MaskRay, espindola
Reviewed By: rnk, MaskRay
Subscribers: wuzish, jholewinski, qcolombet, dschuff, jyknight, emaste, sdardis, nemanjai, jvesely, nhaehnle, sbc100, arichardson, jgravelle-google, aheejin, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, PkmX, jocewei, jsji, lenary, s.egerton, pzheng, cfe-commits, MaskRay, filcab, davide, MatzeB, mehdi_amini, hiraditya, steven_wu, dexonsmith, rupprecht, seiya, llvm-commits
Tags: #llvm, #clang
Differential Revision: https://reviews.llvm.org/D67847
Support sub-register code-gen for XADD is like supporting any other Load
and Store patterns.
No new instruction is introduced.
lock *(u32 *)(r1 + 0) += w2
has exactly the same underlying insn as:
lock *(u32 *)(r1 + 0) += r2
BPF_W width modifier has guaranteed they behave the same at runtime. This
patch merely teaches BPF back-end that BPF_W width modifier could work
GPR32 register class and that's all needed for sub-register code-gen
support for XADD.
test/CodeGen/BPF/xadd.ll updated to include sub-register code-gen tests.
A new testcase test/CodeGen/BPF/xadd_legal.ll is added to make sure the
legal case could pass on all code-gen modes. It could also test dead Def
check on GPR32. If there is no proper handling like what has been done
inside BPFMIChecking.cpp:hasLivingDefs, then this testcase will fail.
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
llvm-svn: 355126
Currently, BPF has XADD (locked add) insn support and the
asm looks like:
lock *(u32 *)(r1 + 0) += r2
lock *(u64 *)(r1 + 0) += r2
The instruction itself does not have a return value.
At the source code level, users often use
__sync_fetch_and_add()
which eventually translates to XADD. The return value of
__sync_fetch_and_add() is supposed to be the old value
in the xadd memory location. Since BPF::XADD insn does not
support such a return value, this patch added a PreEmit
phase to check such a usage. If such an illegal usage
pattern is detected, a fatal error will be reported like
line 4: Invalid usage of the XADD return value
if compiled with -g, or
Invalid usage of the XADD return value
if compiled without -g.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
llvm-svn: 342692
serge-sans-paille