2021년 6월 12일 (토) 오후 8:10, Marc Zyngier <maz@xxxxxxxxxx>님이 작성: > > On Sat, 12 Jun 2021 12:00:14 +0100, > Austin Kim <austindh.kim@xxxxxxxxx> wrote: > > > > From: Austin Kim <austin.kim@xxxxxxx> > > > > Normally local variable 'flags' is defined out of for loop, > > when 'flags' is used as the second parameter in a call to > > spinlock_irq[save/restore] function. > > > > So it had better declear local variable 'flags' ahead of for loop. > > Why better? Reducing the scope of a variable is in general good > practice. Do you see any material advantage in moving this variable > out of the loop? Does the compiler generate better code? First all of, thanks for feedback. I checked how the compiler generate assembly code(before/after) using objdump utility. And then found out that compiler generates the same assembly code. <compiler version: gcc-linaro-7.5.0-2019.12-x86_64_aarch64> ffff80001005f5c8 <vgic_mmio_read_pending>: ffff80001005f5c8: d503233f paciasp ... ffff80001005f63c: 97ffe9af bl ffff800010059cf8 <vgic_get_irq> ffff80001005f640: aa0003f3 mov x19, x0 ffff80001005f644: 943886c3 bl ffff800010e81150 <_raw_spin_lock_irqsave> Let me keep in mind how compiler generate assembly code with new patch, which leads to material advantage. BR, Austin Kim > > Thanks, > > M. > > -- > Without deviation from the norm, progress is not possible. _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
