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authorRich Felker <dalias@aerifal.cx>2016-01-21 19:28:15 +0000
committerRich Felker <dalias@aerifal.cx>2016-01-21 19:43:04 +0000
commit61b1e75f7d8004461f2e18f171c26c2f545eed32 (patch)
tree7a88f8d51ee3f049745b147b7f36fc8ee22e0e62 /src/legacy
parent1315596b510189b5159e742110b504177bdd4932 (diff)
downloadmusl-61b1e75f7d8004461f2e18f171c26c2f545eed32.tar.gz
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.
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