[cfe-commits] [PATCH] ARM strexd and ldrexd intrinsics

[Renato Golin]

On 24 May 2011 22:17, Bruno Cardoso Lopes <bruno.cardoso at gmail.com> wrote:
> Add support for ARM ldrexd/strexd intrinsics. ldrexd and strexd both
> use register pairs to load/store i64 values. The register pair
> constraint specifies that the first register should be even and the
> second the following odd. Teach the pre-regalloc LoadStoreOptimizer to
> use register allocator hints to respect the constraint and teach the
> post-reagalloc to fix the pair (with a very conservative approach)
> when the hint fails. A testcase is also present.

Hi Bruno,

I'm not proficient enough in the regalloc to analyse that part, but
regardless of the intrinsic lowering, I think that's an important
change on itself (maybe on a separate patch?).

But I was wondering about the need for an intrinsic...

First, you declare both ldrexd and strexd but only lowers the former.
Are you planning to implement both? And the single/half/word variants,
too?

Second, I couldn't find ldrex and strex intrinsics, but the
instructions are clearly there. If they were there just for
disassembly purposes, than we need to be able to lower them somehow.

I was wondering if @llvm.atomic.load couldn't trigger LDREX in armv6+
platforms without the need to create new intrinsic...

cheers,
--renato