Uses an inline path for int32 and double. We can test for both with a single compare and in these cases POS is a no-op.

i++ is decomposed as getlocal 0 pos dup one add setlocal 0 The patch doesn't attempt to DUP unsynced constants etc directly. There are probably other uses of DUP but here it doesn't matter.

There's something I don't understand about decomposed ops. JSOP_LOCALINC has the decompose flag set on it, but in the emitted bytecode it doesn't actually seem to be decomposed. The couple of other inc ops I checked actually had the surrogate ops emitted, but not LOCALINC. Is there something I'm missing?

(In reply to Kannan Vijayan [:djvj] from comment #4) > There's something I don't understand about decomposed ops. JSOP_LOCALINC > has the decompose flag set on it, but in the emitted bytecode it doesn't > actually seem to be decomposed. Are you using a recent build? Local/arg ops were decomposed in bug 804636. js> dis(function() { var i; i++; }); flags: LAMBDA loc op ----- -- main: 00000: getlocal 0 00003: pop 00004: localinc 11 00007: getlocal 0 00010: pos 00011: dup 00012: one 00013: add 00014: setlocal 0 00017: pop 00018: pop 00019: stop

https://hg.mozilla.org/projects/ionmonkey/rev/6942d3709009 https://hg.mozilla.org/projects/ionmonkey/rev/79b5f9e429d0 https://hg.mozilla.org/projects/ionmonkey/rev/281c54efd991