On Mon, Mar 23, 2015 at 4:15 PM, Kyrill Tkachov <kyrylo.tkac...@arm.com> wrote: > Hi all, > > The ICE in the PR happens on arm during the hoist pass when the code > generates a SET rtx of the form: > (set (reg:OI) (const_int 0)). It checks whether const_int 0 is a > general_operand for OImode which involves asking the backend whether it's a > legitimate constant. > > arm_legitimate_constant_p_1 explicitly rejects OImode constants as a result > of the fix for PR 46329 > https://gcc.gnu.org/ml/gcc-patches/2011-04/msg00200.html > > This results in gcse using an emit_insn of the SET rtx rather than trying to > do an emit_move_insn > which would have worked in this case. > > From reading the thread I get the impression that the ICE there was caused > by reload and coproc_secondary_reload_class behaving weirdly. We're now > using LRA and > SECONDARY_INPUT_RELOAD_CLASS and SECONDARY_OUTPUT_RELOAD_CLASS which are the > only users of coproc_secondary_reload_class are no longer used. > > I removed the restriction on constants for these large modes in > arm_legitimate_constant_p_1 and the testcases in PR 46329 all work fine. > Bootstrap, testing and building various vector workloads also didn't show > any problems. > > Is this the right way to go for this? > If so, ok for trunk? > > The ICE in this PR happens on a recently added testcase to > gcc.c-torture/execute/ and this patch fixes that, so no new testcase is > added. Jakub mentioned that maybe the testcase can be modified to manually > perform the lowering done in his patch to potentially trigger this on older > gcc versions, but I'm not sure how that would be done. > The problem is that something is generating OImode moves that I think can > only be done in the vector form of the testcase, so I'm not entirely > convinced that it's reproducible on 4.9 and 4.8.
This is OK for trunk now that we are in wide-int mode on trunk for the ARM port. Thanks, Ramana > > Thanks, > Kyrill > > Thanks, > Kyrill > > 2015-03-23 Kyrylo Tkachov <kyrylo.tkac...@arm.com> > > PR target/65489 > * config/arm/arm.c (arm_legitimate_constant_p_1): Remove restriction > on constants for NEON VSTRUCT modes.
