This NFC changeset standardizes the suffixes used for LSE Atomics
instructions.
It changes the existing suffixes - 'b', 'h', 's', 'd' - to the existing
standard 'B', 'H', 'W' and 'X'.
This changeset is the result of the code review discussion for D35319.
Patch by: steleman
Differential Revision: https://reviews.llvm.org/D35927
llvm-svn: 309384
Implemented support to AArch64 codegen for ARMv8.1 Large System
Extensions atomic instructions. Where supported, these instructions can
provide atomic operations with higher performance.
Currently supported operations include: fetch_add, fetch_or, fetch_xor,
fetch_smin, fetch_min/max (signed and unsigned), swap, and
compare_exchange.
This implementation implies sequential-consistency ordering, more
relaxed ordering is under development.
Subtarget->hasLSE is currently supported for Cavium ThunderX2T99.
Patch by Ananth Jasty.
Differential Revision: https://reviews.llvm.org/D33586
Change-Id: I82f6d3d64255622791ceb0715b7ab9f4dc4d4b2c
llvm-svn: 305893
Single-threaded fences aren't required to provide any synchronization with
other processing elements so there's no need for a DMB. They should still be a
barrier for compiler optimizations though.
llvm-svn: 300905
We were relying on the misleadingly-names $status result to actually be the
status. Actually it's just a scratch register that may or may not be valid (and
is the inverse of the real ststus anyway). Success can be determined by
comparing the value loaded against the one we wanted to see for "cmpxchg
strong" loops like this.
Should fix PR28819.
llvm-svn: 277513
FastRegAlloc works only at the basic-block level and spills all live-out
registers. Unfortunately for a stack-based cmpxchg near the spill slots, this
can perpetually clear the exclusive monitor, which means the cmpxchg will never
succeed.
I believe the only way to handle this within LLVM is by expanding the loop
post-regalloc. We don't want this in general because it severely limits the
optimisations that can be done, so we limit this to -O0 compilations.
It's an ugly hack, and about the one good point in the whole mess is that we
can treat all cmpxchg operations in the most naive way possible (seq_cst, no
clrex faff) without affecting correctness.
Should fix PR25526.
llvm-svn: 266339
Summary:
In the context of http://wg21.link/lwg2445 C++ uses the concept of
'stronger' ordering but doesn't define it properly. This should be fixed
in C++17 barring a small question that's still open.
The code currently plays fast and loose with the AtomicOrdering
enum. Using an enum class is one step towards tightening things. I later
also want to tighten related enums, such as clang's
AtomicOrderingKind (which should be shared with LLVM as a 'C++ ABI'
enum).
This change touches a few lines of code which can be improved later, I'd
like to keep it as NFC for now as it's already quite complex. I have
related changes for clang.
As a follow-up I'll add:
bool operator<(AtomicOrdering, AtomicOrdering) = delete;
bool operator>(AtomicOrdering, AtomicOrdering) = delete;
bool operator<=(AtomicOrdering, AtomicOrdering) = delete;
bool operator>=(AtomicOrdering, AtomicOrdering) = delete;
This is separate so that clang and LLVM changes don't need to be in sync.
Reviewers: jyknight, reames
Subscribers: jyknight, llvm-commits
Differential Revision: http://reviews.llvm.org/D18775
llvm-svn: 265602
Summary:
Make use of isAtLeastRelease/Acquire in the ARM/AArch64 backends
These helper functions are introduced in D4844.
Depends D4844
Test Plan: make check-all passes
Reviewers: jfb
Subscribers: aemerson, llvm-commits, mcrosier, reames
Differential Revision: http://reviews.llvm.org/D4937
llvm-svn: 215902
This commit starts with a "git mv ARM64 AArch64" and continues out
from there, renaming the C++ classes, intrinsics, and other
target-local objects for consistency.
"ARM64" test directories are also moved, and tests that began their
life in ARM64 use an arm64 triple, those from AArch64 use an aarch64
triple. Both should be equivalent though.
This finishes the AArch64 merge, and everyone should feel free to
continue committing as normal now.
llvm-svn: 209577
Joel Jones