In current mozilla-central, GCC is giving me instances of this warning for each .cpp file that #includes Architecture-x64.h (directly or indirectly) and does not use the function in question: { 0:47.42 In file included from /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/jit/Registers.h:16:0, 0:47.42 from /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/jit/Snapshots.h:17, 0:47.42 from /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/jit/JitFrameIterator.h:17, 0:47.42 from /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/vm/Stack.h:16, 0:47.42 from /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/vm/Runtime.h:41, 0:47.42 from /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/jscntxt.h:15, 0:47.42 from /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/frontend/TokenStream.h:19, 0:47.42 from /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/frontend/ParseNode.h:12, 0:47.42 from /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/frontend/FullParseHandler.h:12, 0:47.42 from /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/frontend/Parser.h:17, 0:47.44 from /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/frontend/Parser-inl.h:10, 0:47.44 from /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/frontend/Parser.cpp:20: 0:47.44 Warning: -Wunused-function in /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/jit/x64/Architecture-x64.h: 'bool js::jit::hasUnaliasedDouble()' defined but not used 0:47.45 /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/jit/x64/Architecture-x64.h:244:13: warning: 'bool js::jit::hasUnaliasedDouble()' defined but not used [-Wunused-function] 0:47.45 static bool hasUnaliasedDouble() { 0:47.45 ^ 0:47.45 Warning: -Wunused-function in /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/jit/x64/Architecture-x64.h: 'bool js::jit::hasMultiAlias()' defined but not used 0:47.46 /scratch/work/builds/mozilla-central/mozilla-central.12-12-07.08-38/mozilla/js/src/jit/x64/Architecture-x64.h:249:13: warning: 'bool js::jit::hasMultiAlias()' defined but not used [-Wunused-function] 0:47.46 static bool hasMultiAlias() { 0:47.46 ^ These functions were added in bug 991153, which landed today. Marty, is there a reason these need to be declared as "static" (note that they're defined in .h files)? If we drop that keyword (maybe replacing it with 'inline'), I think this problem will go away.

Indeed (not having inline => multiple definitions, and that doesn't seem enough to introduce Architecture-x{64,86}.cpp).