Currently we have one opcode per condition flag, most cmov instruction can actually share the same way we compute the opcode as the Jcc instruction encoding.

Extract CMOV patch from Bug 1433111 patch, and apply nits from IRC: - MOZ_CRASH (MOZ_RELEASE_ASSERT) if the CPU does not support cmov instructions.

Comment on attachment 8947799 [details] [diff] [review] Generalized x86/x64 cmov encoding. Review of attachment 8947799 [details] [diff] [review]: ----------------------------------------------------------------- Very nice, thanks! ::: js/src/jit/x64/Assembler-x64.h @@ +464,5 @@ > > + void cmovCCq(Condition cond, const Operand& src, Register dest) { > + X86Encoding::Condition cc = static_cast<X86Encoding::Condition>(cond); > + switch (src.kind()) { > + case Operand::REG: Nit: indent case labels with 2 more spaces, also in cmovCCl ::: js/src/jit/x86-shared/Assembler-x86-shared.cpp @@ +266,5 @@ > CPUInfo::SSEVersion CPUInfo::maxSSEVersion = UnknownSSE; > CPUInfo::SSEVersion CPUInfo::maxEnabledSSEVersion = UnknownSSE; > bool CPUInfo::avxPresent = false; > bool CPUInfo::avxEnabled = false; > +bool CPUInfo::cmovPresent = false; Nit: can remove this line

Pushed by npierron@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/61d73dd6b95f Generalized x86/x64 cmov encoding. r=jandem

Comment on attachment 8947799 [details] [diff] [review] Generalized x86/x64 cmov encoding. See bug 1431173 comment 6.

Comment on attachment 8947799 [details] [diff] [review] Generalized x86/x64 cmov encoding. Spectre-related fix. Taking for 59b8.