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6d1a70dd0a
Previously the pattern to extract status flags from inline assembly blocks was to use setcc in the block to write the flag to a register. This was suboptimal in a few ways: - It would lead to code like: sete %cl; test %cl; jne, i.e. a flag would just be loaded into a register and then reloaded to a flag. - The setcc would force the block to use an additional register. - If the client code didn't care for the flag value then the setcc would be entirely pointless but could not be eliminated by the optimizer. A more modern inline asm construct (since gcc 6 and clang 9) allows for "flag output operands", where a C variable can be written directly from a flag. The optimizer can then use this to produce direct code where the flag does not take a trip through a register. In practice this makes each affected operation sequence shorter by five bytes of instructions. It's unlikely this has a measurable performance impact. Reviewed by: kib, markj, mjg Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D23869 |
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| .. | ||
| pc | ||
| xen | ||
| _align.h | ||
| _bus.h | ||
| _inttypes.h | ||
| _limits.h | ||
| _stdint.h | ||
| _types.h | ||
| acpica_machdep.h | ||
| apm_bios.h | ||
| asm.h | ||
| asmacros.h | ||
| atomic.h | ||
| bus.h | ||
| bus_dma.h | ||
| clock.h | ||
| counter.h | ||
| cpu.h | ||
| cpufunc.h | ||
| cputypes.h | ||
| csan.h | ||
| db_machdep.h | ||
| dump.h | ||
| efi.h | ||
| elf.h | ||
| endian.h | ||
| exec.h | ||
| fdt.h | ||
| float.h | ||
| floatingpoint.h | ||
| fpu.h | ||
| frame.h | ||
| gdb_machdep.h | ||
| ieeefp.h | ||
| in_cksum.h | ||
| intr_machdep.h | ||
| iodev.h | ||
| kdb.h | ||
| limits.h | ||
| md_var.h | ||
| memdev.h | ||
| metadata.h | ||
| minidump.h | ||
| mp_watchdog.h | ||
| nexusvar.h | ||
| npx.h | ||
| ofw_machdep.h | ||
| param.h | ||
| pcb.h | ||
| pci_cfgreg.h | ||
| pcpu.h | ||
| pcpu_aux.h | ||
| pmap.h | ||
| pmc_mdep.h | ||
| ppireg.h | ||
| proc.h | ||
| procctl.h | ||
| profile.h | ||
| psl.h | ||
| ptrace.h | ||
| pvclock.h | ||
| reg.h | ||
| reloc.h | ||
| resource.h | ||
| runq.h | ||
| segments.h | ||
| setjmp.h | ||
| sf_buf.h | ||
| sgx.h | ||
| sgxreg.h | ||
| sigframe.h | ||
| signal.h | ||
| smp.h | ||
| specialreg.h | ||
| stack.h | ||
| stdarg.h | ||
| sysarch.h | ||
| timerreg.h | ||
| trap.h | ||
| tss.h | ||
| ucontext.h | ||
| vdso.h | ||
| vm.h | ||
| vmm.h | ||
| vmm_dev.h | ||
| vmm_instruction_emul.h | ||
| vmparam.h | ||