On December 20, 2016 5:01:19 PM GMT+01:00, Kyrill Tkachov <kyrylo.tkac...@foss.arm.com> wrote: >Hi all, > >The testcase in this patch generates bogus assembly for arm with -O1 >-mfloat-abi=soft: > strd r4, [#0, r3] > >This is due to non-canonical RTL being generated during expansion: >(set (mem:DI (plus:SI (const_int 0 [0]) > (reg/f:SI 153)) [0 MEM[symbol: a, index: _26, offset: 0B]+0 S8 A64]) > (reg:DI 154)) > >Note the (plus (const_int 0) (reg)). This is being generated in >gen_addr_rtx in tree-ssa-address.c >where it creates an explicit PLUS rtx through gen_rtx_PLUS, which >doesn't try to canonicalise its arguments >or simplify. The correct thing to do is to use simplify_gen_binary that >will handle all this properly.
But it has to match up the validity check which passes down exactly the same RTL(?) Or does this stem from propagation simplifying a MEM after IVOPTs? >I didn't change the other gen_rtx_PLUS calls in this function as their >results is later used in XEXP operations >that seem to rely on a PLUS expression being explicitly produced, but >this particular call doesn't, so it's okay >to change it. With this patch the sane assembly is generated: > strd r4, [r3] > >Bootstrapped and tested on arm-none-linux-gnueabihf, x86_64, >aarch64-none-linux-gnu. > >Ok for trunk? > >Thanks, >Kyrill > >2016-12-20 Kyrylo Tkachov <kyrylo.tkac...@arm.com> > > * tree-ssa-address.c (gen_addr_rtx): Use simplify_gen_binary to add > *addr to act_elem. > >2016-12-20 Kyrylo Tkachov <kyrylo.tkac...@arm.com> > > * gcc.dg/20161219.c: New test.
