This change switches both targets from using target specific CompilerBarrier nodes to the recently introduced generic MEMBARRIER instruction.
A couple things to call out.
First, this changes the assembly comment printed. I'm not sure this matters, but if it does, we can simply drop this patch. This is a minor clean up at best.
Second, the ordering operand on the target instruction appears to be unused. We could easily add ordering to the generic instruction, but since we don't seem to have a motivating case in tree, I simply dropped the ordering when selecting to the generic instruction.
Differential Revision: https://reviews.llvm.org/D141513
OpenCL 2.0 introduces the notion of memory scopes in atomic operations to
global and local memory. These scopes restrict how synchronization is
achieved, which can result in improved performance.
This change extends existing notion of synchronization scopes in LLVM to
support arbitrary scopes expressed as target-specific strings, in addition to
the already defined scopes (single thread, system).
The LLVM IR and MIR syntax for expressing synchronization scopes has changed
to use *syncscope("<scope>")*, where <scope> can be "singlethread" (this
replaces *singlethread* keyword), or a target-specific name. As before, if
the scope is not specified, it defaults to CrossThread/System scope.
Implementation details:
- Mapping from synchronization scope name/string to synchronization scope id
is stored in LLVM context;
- CrossThread/System and SingleThread scopes are pre-defined to efficiently
check for known scopes without comparing strings;
- Synchronization scope names are stored in SYNC_SCOPE_NAMES_BLOCK in
the bitcode.
Differential Revision: https://reviews.llvm.org/D21723
llvm-svn: 307722
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: 300904
