Commit Graph

8 Commits

Author SHA1 Message Date
Tim Northover 277066ab43 X86: expand atomics in IR instead of as MachineInstrs.
The logic for expanding atomics that aren't natively supported in
terms of cmpxchg loops is much simpler to express at the IR level. It
also allows the normal optimisations and CodeGen improvements to help
out with atomics, instead of using a limited set of possible
instructions..

rdar://problem/13496295

llvm-svn: 212119
2014-07-01 18:53:31 +00:00
Tim Northover 420a216817 IR: add "cmpxchg weak" variant to support permitted failure.
This commit adds a weak variant of the cmpxchg operation, as described
in C++11. A cmpxchg instruction with this modifier is permitted to
fail to store, even if the comparison indicated it should.

As a result, cmpxchg instructions must return a flag indicating
success in addition to their original iN value loaded. Thus, for
uniformity *all* cmpxchg instructions now return "{ iN, i1 }". The
second flag is 1 when the store succeeded.

At the DAG level, a new ATOMIC_CMP_SWAP_WITH_SUCCESS node has been
added as the natural representation for the new cmpxchg instructions.
It is a strong cmpxchg.

By default this gets Expanded to the existing ATOMIC_CMP_SWAP during
Legalization, so existing backends should see no change in behaviour.
If they wish to deal with the enhanced node instead, they can call
setOperationAction on it. Beware: as a node with 2 results, it cannot
be selected from TableGen.

Currently, no use is made of the extra information provided in this
patch. Test updates are almost entirely adapting the input IR to the
new scheme.

Summary for out of tree users:
------------------------------

+ Legacy Bitcode files are upgraded during read.
+ Legacy assembly IR files will be invalid.
+ Front-ends must adapt to different type for "cmpxchg".
+ Backends should be unaffected by default.

llvm-svn: 210903
2014-06-13 14:24:07 +00:00
Tim Northover e94a518a22 IR: add a second ordering operand to cmpxhg for failure
The syntax for "cmpxchg" should now look something like:

	cmpxchg i32* %addr, i32 42, i32 3 acquire monotonic

where the second ordering argument gives the required semantics in the case
that no exchange takes place. It should be no stronger than the first ordering
constraint and cannot be either "release" or "acq_rel" (since no store will
have taken place).

rdar://problem/15996804

llvm-svn: 203559
2014-03-11 10:48:52 +00:00
NAKAMURA Takumi b72e763325 llvm/test/CodeGen/X86/Atomics-64.ll: Tweak for 2nd RUN not to overwrite %t. It sometimes causes spurious failure on lit win32.
Feel free to prune or suppress each output.

llvm-svn: 172823
2013-01-18 14:52:02 +00:00
Eli Friedman f6fbfd3f83 Last batch of test conversions to new atomic instructions.
llvm-svn: 140585
2011-09-27 00:17:29 +00:00
Dan Gohman 40503396da Eliminate more uses of llvm-as and llvm-dis.
llvm-svn: 81290
2009-09-08 23:54:48 +00:00
Jakob Stoklund Olesen 9d7fb58581 Help DejaGnu avoid pipe-jam by producing less output from certain test cases.
When a test fails with more than a pipeful of output on stdout AND stderr, one
of the DejaGnu programs blocks. The problem can be avoided by redirecting
stdout to a file.

llvm-svn: 71919
2009-05-16 00:34:42 +00:00
Dale Johannesen bb170bd08c Test all currently supported atomic builtins on x86-{32,64}.
These just test that they go through the BE.

llvm-svn: 55208
2008-08-22 22:39:21 +00:00