Re: [PATCH v7] RISCV: Inline subword atomic ops

[Jeff Law <jeffreyalaw@gmail.com>]

On 4/18/23 15:41, Patrick O'Neill wrote:
> RISC-V has no support for subword atomic operations; code currently
> generates libatomic library calls.
> 
> This patch changes the default behavior to inline subword atomic calls
> (using the same logic as the existing library call).
> Behavior can be specified using the -minline-atomics and
> -mno-inline-atomics command line flags.
> 
> gcc/libgcc/config/riscv/atomic.c has the same logic implemented in asm.
> This will need to stay for backwards compatibility and the
> -mno-inline-atomics flag.
> 
> 2023-04-18 Patrick O'Neill <patrick@rivosinc.com>
> 
> 	PR target/104338
> 	* riscv-protos.h: Add helper function stubs.
> 	* riscv.cc: Add helper functions for subword masking.
> 	* riscv.opt: Add command-line flag.
> 	* sync.md: Add masking logic and inline asm for fetch_and_op,
> 	fetch_and_nand, CAS, and exchange ops.
> 	* invoke.texi: Add blurb regarding command-line flag.
> 	* inline-atomics-1.c: New test.
> 	* inline-atomics-2.c: Likewise.
> 	* inline-atomics-3.c: Likewise.
> 	* inline-atomics-4.c: Likewise.
> 	* inline-atomics-5.c: Likewise.
> 	* inline-atomics-6.c: Likewise.
> 	* inline-atomics-7.c: Likewise.
> 	* inline-atomics-8.c: Likewise.
> 	* atomic.c: Add reference to duplicate logic.
This is OK for the trunk.  I think the only question is whether or not 
you're going to contribute to GCC regularly.  If so, we should go ahead 
and get you write access so you can commit ACK's changes.  If you're not 
going to be making regular contributions, then I can go ahead and commit 
it for you.

Jeff