Richard Guenther wrote: > On Wed, Feb 22, 2012 at 11:39 AM, Georg-Johann Lay <a...@gjlay.de> wrote: >> Denis Chertykov wrote: >>> 2012/2/21 Richard Henderson: >>>> On 02/21/12 09:08, Georg-Johann Lay wrote: >>>>> PR rtl-optimization/50063 >>>>> * config/avr/avr.md (movhi_sp_r): Handle -1 (unknown IRQ state) >>>>> and 2 (8-bit SP) in operand 2. >>>>> * config/avr/avr.c (avr_prologue_setup_frame): Adjust prologue >>>>> setup to use movhi_sp_r instead of vanilla move to write SP. >>>>> Adjust REG_CFA notes to superseed unspec. >>>>> (expand_epilogue): Adjust epilogue setup to use read_sp instead >>>>> of vanilla move. >>>>> As function body might contain CLI or SEI: Use irq_state 0 (IRQ >>>>> known to be off) only with TARGET_NO_INTERRUPTS. Never use >>>>> irq_state 1 (IRQ known to be on) here. >>>> The CFA bits in avr_prologue_setup_frame look good. >>>> I'll let Denis or Eric review the movhi_sp_r change. >>> Approved. >>> >>> Denis. >> Here is a patchlet for 4.6. It just sets -fno-dse to work around the problem >> because I think back-porting all what's needed is too much change. >> >> Compiling avr-libc without DSE gives the same sizes for all objects which >> shows >> that this is not a crucial optimization for avr. >> >> Ok for 4.6 branch? > > I don't think this kind of fixes are wanted. The patch misses a > testcase to backport > and the issue surely not only affects DSE. > > Richard.
Actually, hacking the backend to work around assumptions in rtl-optimizers by hiding information in unspec_volatile is not wanted, too. If I understand correctly, no one is inclined to fix the root cause of the bug, i.e. don't let RTL optimizers make assumptions that shred some backends. Johann
