overhaul sh atomics for new atomics framework, add j-core cas.l backend

sh needs runtime-selected atomic backends since there are a number of
supported models that use non-forwards-compatible (non-smp-compatible)
atomic mechanisms. previously, the code paths for this were highly
inefficient since they involved C function calls with multiple
branches in the callee and heavy spills in the caller. the new code
performs calls the runtime-selected asm fragment from inline asm with
extremely minimal clobbers, rather than using a function call.

for the sh4a case where the atomic mechanism is known and there is no
forward-compatibility issue, the movli.l and movco.l instructions are
provided as a_ll and a_sc, allowing the new shared atomic.h to
generate efficient inline versions of all the basic atomic operations
without needing a cas loop.

1 files changed, 0 insertions, 15 deletions

diff --git a/arch/sh/src/sh_atomic.h b/arch/sh/src/sh_atomic.h
deleted file mode 100644
index 054c2a32..00000000
--- a/arch/sh/src/sh_atomic.h
+++ /dev/null
@@ -1,15 +0,0 @@
-#ifndef _SH_ATOMIC_H
-#define _SH_ATOMIC_H
-
-#define SH_A_GUSA 0
-#define SH_A_LLSC 1
-#define SH_A_CAS 2
-#if !defined(__SH3__) && !defined(__SH4__)
-#define SH_A_IMASK 3
-#else
-#define SH_A_IMASK -1LL /* unmatchable by unsigned int */
-#endif
-
-extern __attribute__((__visibility__("hidden"))) unsigned __sh_atomic_model;
-
-#endif