Re: Need help with PR71976 combine.c::get_last_value returns a wrong result

2016-07-29 Thread Segher Boessenkool
On Fri, Jul 29, 2016 at 11:05:13AM +0200, Georg-Johann Lay wrote: > There might still problems linger around if hard-regs are used: > > Suppose we set the reg in DImode and then get_last_value is called for the > same reg in SImode. Using the DI value might be wrong, e.g. if it is used > to com

Re: Need help with PR71976 combine.c::get_last_value returns a wrong result

2016-07-29 Thread Georg-Johann Lay
On 29.07.2016 09:47, Segher Boessenkool wrote: Hi Johann, I tested a variant of your patch, building Linux for 32 different (sub-)architectures; surprisingly (to me) there are no regressions at all. I am not so surprised because most backends don't make such an intense use of hard-regs like t

Re: Need help with PR71976 combine.c::get_last_value returns a wrong result

2016-07-29 Thread Segher Boessenkool
Hi Johann, I tested a variant of your patch, building Linux for 32 different (sub-)architectures; surprisingly (to me) there are no regressions at all. Do you want to send it to gcc-patches? Segher diff --git a/gcc/combine.c b/gcc/combine.c index 77e0d2b..750bf83 100644 --- a/gcc/combine.c ++

Re: Need help with PR71976 combine.c::get_last_value returns a wrong result

2016-07-27 Thread Segher Boessenkool
On Wed, Jul 27, 2016 at 09:14:27PM +0200, Georg-Johann Lay wrote: > >diff --git a/gcc/combine.c b/gcc/combine.c > >index 77e0d2b..dec6226 100644 > >--- a/gcc/combine.c > >+++ b/gcc/combine.c > >@@ -9977,6 +9977,9 @@ reg_num_sign_bit_copies_for_combine (const_rtx x, > >machine_mode mode, > >

Re: Need help with PR71976 combine.c::get_last_value returns a wrong result

2016-07-27 Thread Georg-Johann Lay
Segher Boessenkool schrieb: On Tue, Jul 26, 2016 at 03:38:18PM +0200, Georg-Johann Lay wrote: @@ -13206,6 +13206,13 @@ get_last_value (const_rtx x) && DF_INSN_LUID (rsp->last_set) >= subst_low_luid) return 0; + /* If the lookup is for a hard register make sure that value contains at

Re: Need help with PR71976 combine.c::get_last_value returns a wrong result

2016-07-27 Thread Segher Boessenkool
On Tue, Jul 26, 2016 at 03:38:18PM +0200, Georg-Johann Lay wrote: > >>@@ -13206,6 +13206,13 @@ get_last_value (const_rtx x) > >> && DF_INSN_LUID (rsp->last_set) >= subst_low_luid) > >> return 0; > >> > >>+ /* If the lookup is for a hard register make sure that value contains > >>at > >>

Re: Need help with PR71976 combine.c::get_last_value returns a wrong result

2016-07-26 Thread Georg-Johann Lay
On 26.07.2016 14:51, Segher Boessenkool wrote: On Tue, Jul 26, 2016 at 02:14:49PM +0200, Georg-Johann Lay wrote: which returns const0_rtx because reg 18 is set in insn 43 to const0_rtx. Total outcome is that the right shift of reg:DI 18 is transformed to a no-op move and cancelled out in the rem

Re: Need help with PR71976 combine.c::get_last_value returns a wrong result

2016-07-26 Thread Segher Boessenkool
On Tue, Jul 26, 2016 at 02:14:49PM +0200, Georg-Johann Lay wrote: > >>which returns const0_rtx because reg 18 is set in insn 43 to const0_rtx. > >>Total outcome is that the right shift of reg:DI 18 is transformed to a > >>no-op move and cancelled out in the remainder. > > > >Why does num_sign_bit_c

Re: Need help with PR71976 combine.c::get_last_value returns a wrong result

2016-07-26 Thread Georg-Johann Lay
On 25.07.2016 23:05, Segher Boessenkool wrote: On Mon, Jul 25, 2016 at 02:28:28PM +0200, Georg-Johann Lay wrote: (insn 43 31 44 2 (set (reg:QI 18 r18) (const_int 0 [0])) bug-combin.c:29 56 {movqi_insn} (nil)) (insn 51 50 52 2 (set (reg:QI 16 r16) (const_int 40 [0x28])) bu

Re: Need help with PR71976 combine.c::get_last_value returns a wrong result

2016-07-25 Thread Segher Boessenkool
On Mon, Jul 25, 2016 at 02:28:28PM +0200, Georg-Johann Lay wrote: > (insn 43 31 44 2 (set (reg:QI 18 r18) > (const_int 0 [0])) bug-combin.c:29 56 {movqi_insn} > (nil)) > (insn 51 50 52 2 (set (reg:QI 16 r16) > (const_int 40 [0x28])) bug-combin.c:29 56 {movqi_insn} > (nil)