From 89f185fe8a036b0fabce30b20c480cf1c832bdd7 Mon Sep 17 00:00:00 2001 From: Russ Cox Date: Thu, 26 Jun 2014 11:54:39 -0400 Subject: all: remove 'extern register M *m' from runtime MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The runtime has historically held two dedicated values g (current goroutine) and m (current thread) in 'extern register' slots (TLS on x86, real registers backed by TLS on ARM). This CL removes the extern register m; code now uses g->m. On ARM, this frees up the register that formerly held m (R9). This is important for NaCl, because NaCl ARM code cannot use R9 at all. The Go 1 macrobenchmarks (those with per-op times >= 10 µs) are unaffected: BenchmarkBinaryTree17 5491374955 5471024381 -0.37% BenchmarkFannkuch11 4357101311 4275174828 -1.88% BenchmarkGobDecode 11029957 11364184 +3.03% BenchmarkGobEncode 6852205 6784822 -0.98% BenchmarkGzip 650795967 650152275 -0.10% BenchmarkGunzip 140962363 141041670 +0.06% BenchmarkHTTPClientServer 71581 73081 +2.10% BenchmarkJSONEncode 31928079 31913356 -0.05% BenchmarkJSONDecode 117470065 113689916 -3.22% BenchmarkMandelbrot200 6008923 5998712 -0.17% BenchmarkGoParse 6310917 6327487 +0.26% BenchmarkRegexpMatchMedium_1K 114568 114763 +0.17% BenchmarkRegexpMatchHard_1K 168977 169244 +0.16% BenchmarkRevcomp 935294971 914060918 -2.27% BenchmarkTemplate 145917123 148186096 +1.55% Minux previous reported larger variations, but these were caused by run-to-run noise, not repeatable slowdowns. Actual code changes by Minux. I only did the docs and the benchmarking. LGTM=dvyukov, iant, minux R=minux, josharian, iant, dave, bradfitz, dvyukov CC=golang-codereviews https://golang.org/cl/109050043 --- src/pkg/runtime/runtime.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'src/pkg/runtime/runtime.h') diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h index 5115503789..0f630abbf2 100644 --- a/src/pkg/runtime/runtime.h +++ b/src/pkg/runtime/runtime.h @@ -102,14 +102,13 @@ typedef struct DebugVars DebugVars; * local storage indexed by a pseudo-register TLS. See zasmhdr in * src/cmd/dist/buildruntime.c for details, and be aware that the linker may * make further OS-specific changes to the compiler's output. For example, - * 6l/linux rewrites 0(TLS) as -16(FS). + * 6l/linux rewrites 0(TLS) as -8(FS). * * Every C file linked into a Go program must include runtime.h so that the * C compiler (6c, 8c, etc.) knows to avoid other uses of these dedicated * registers. The Go compiler (6g, 8g, etc.) knows to avoid them. */ extern register G* g; -extern register M* m; /* * defined constants @@ -907,7 +906,7 @@ uint64 runtime·atomicload64(uint64 volatile*); void* runtime·atomicloadp(void* volatile*); void runtime·atomicstorep(void* volatile*, void*); -void runtime·setmg(M*, G*); +void runtime·setg(G*); void runtime·newextram(void); void runtime·exit(int32); void runtime·breakpoint(void); -- cgit v1.3-5-g9baa