Ping for trunk? Hale
> -----Original Message----- > From: Richard Sandiford [mailto:rdsandif...@googlemail.com] > Sent: Friday, February 27, 2015 4:04 AM > To: Terry Guo > Cc: Segher Boessenkool; Richard Sandiford; GCC Patches; Hale Wang > Subject: Re: Ping : [PATCH] [gcc, combine] PR46164: Don't combine the insns > if a volatile register is contained. > > Terry Guo <flame...@gmail.com> writes: > > On Thu, Feb 26, 2015 at 1:55 PM, Segher Boessenkool > > <seg...@kernel.crashing.org> wrote: > >> On Tue, Feb 17, 2015 at 11:39:34AM +0800, Terry Guo wrote: > >>> On Sun, Feb 15, 2015 at 7:35 PM, Segher Boessenkool > >>> <seg...@kernel.crashing.org> wrote: > >>> > Hi Terry, > >>> > > >>> > I still think this is stage1 material. > >>> > > >>> >> + /* Don't combine if dest contains a user specified register and > >>> >> i3 contains > >>> >> + ASM_OPERANDS, because the user specified register (same with > >>> >> dest) in i3 > >>> >> + would be replaced by the src of insn which might be different > with > >>> >> + the user's expectation. */ > >>> > > >>> > "Do not eliminate a register asm in an asm input" or similar? > >>> > Text explaining why REG_USERVAR_P && HARD_REGISTER_P works > here > >>> > would be good to have, too. > >> > >>> diff --git a/gcc/combine.c b/gcc/combine.c index f779117..aeb2854 > >>> 100644 > >>> --- a/gcc/combine.c > >>> +++ b/gcc/combine.c > >>> @@ -1779,7 +1779,7 @@ can_combine_p (rtx_insn *insn, rtx_insn *i3, > >>> rtx_insn *pred ATTRIBUTE_UNUSED, { > >>> int i; > >>> const_rtx set = 0; > >>> - rtx src, dest; > >>> + rtx src, dest, asm_op; > >>> rtx_insn *p; > >>> #ifdef AUTO_INC_DEC > >>> rtx link; > >>> @@ -1914,6 +1914,14 @@ can_combine_p (rtx_insn *insn, rtx_insn *i3, > rtx_insn *pred ATTRIBUTE_UNUSED, > >>> set = expand_field_assignment (set); > >>> src = SET_SRC (set), dest = SET_DEST (set); > >>> > >>> + /* Use REG_USERVAR_P and HARD_REGISTER_P to check whether > DEST is a user > >>> + specified register, and do not eliminate such register if it is in an > >>> + asm input because we may end up with something different with > user's > >>> + expectation. */ > >> > >> That doesn't explain why this will hit (almost) only on register asms. > >> The user's expectation doesn't matter that much either: GCC would > >> violate its own documentation / promises, that matters more ;-) > >> > >>> + if (REG_P (dest) && REG_USERVAR_P (dest) && HARD_REGISTER_P > (dest) > >>> + && ((asm_op = extract_asm_operands (PATTERN (i3))) != NULL)) > >> > >> You do not need the temporary variable, nor the != 0 or the extra > >> parens; just write > >> > >> && extract_asm_operands (PATTERN (i3)) > >> > >> Cheers, > >> > >> > >> Segher > > > > Thanks for comments. Patch is updated now. Please review again. > > Looks good to me FWIW. > > Thanks, > Richard
