Re: Remove mode argument from gen_rtx_SET

[Franz Sirl <Franz.Sirl-kernel@lauterbach.com>]

Am 2015-05-07 um 13:37 schrieb Richard Sandiford:
> One problem with the automatically-generated gen_rtx_FOO () macros
> is that they always have a mode parameter, even for codes like SET
> where the mode should always be VOIDmode.  This inevitably leads to
> cases where a caller accidentally passes something other than VOIDmode.
> E.g. when expanding an SImode move, the temptation is to make everything
> SImode, even the SETs.  This in turn can cause two instructions to appear
> different simply because their SETs have different modes, even though the
> SET_DEST and SET_SRC are identical.
>
> E.g. for gcc/testsuite/g++.dg/torture/pr34651.C on lm32-elf we have
> the following before jump2:
>
>    (jump_insn 42 191 43 5 (set (pc)
> 	  (if_then_else (eq:SI (reg:SI 13 r13 [orig:43 inHotKey$4+-3 ] [43])
> 		  (const_int 0 [0]))
> 	      (label_ref 53)
> 	      (pc))) gcc/testsuite/g++.dg/torture/pr34651.C:22 22 {*beq}
>         (expr_list:REG_DEAD (reg:SI 13 r13 [orig:43 inHotKey$4+-3 ] [43])
> 	  (int_list:REG_BR_PROB 5000 (nil)))
>     -> 53)
>    (note 43 42 48 6 [bb 6] NOTE_INSN_BASIC_BLOCK)
>    (insn 48 43 47 6 (set (reg:SI 2 r2)
> 	  (mem/u/c:SI (reg:SI 1 r1) [4  S4 A32])) gcc/testsuite/g++.dg/torture/pr34651.C:22 7 {movsi_insn}
>         (expr_list:REG_DEAD (reg:SI 1 r1)
> 	  (nil)))
>    [...]
>    (code_label 53 169 54 7 6 "" [1 uses])
>    (note 54 53 12 7 [bb 7] NOTE_INSN_BASIC_BLOCK)
>    (insn 12 54 57 7 (set:SI (reg/f:SI 2 r2 [orig:46 D.2050 ] [46])
> 	  (mem/u/c:SI (reg:SI 1 r1) [4  S4 A32])) gcc/testsuite/g++.dg/torture/pr34651.C:22 7 {movsi_insn}
>         (expr_list:REG_DEAD (reg:SI 1 r1)
> 	  (expr_list:REG_EQUAL (symbol_ref/f:SI ("*.LC3") [flags 0x2]  <var_decl # *.LC3>)
> 	      (nil))))
>
> where insns 12 and 48 are identical except for the :SI on the SET.
> This difference prevents us from merging the heads of the two blocks;
> after removing it we replace the two loads with a single load before
> the branch.
>
> This patch removes the mode argument from gen_rtx_SET and updates
> all callers.  I used a script to (try to) make sure that all callers
> really had been caught.  I also built one target per CPU just in case.
> There were some changes in gcc.dg, g++.dg and gcc.c-torture assembly
> code for c6x-elf, lm32-elf and v850-elf, but all of them seemed to be
> code improvements from removing duplicated instructions.  (Other ports
> also passed spurious modes but apparently not in a way that affects
> the tests I'd tried.)  Also tested on x86_64-linux-gnu.  OK to install?
>
> BTW, I've split the patch up into two, the last bit being a mechanical
> removal of modes.  (I did it by hand though to try to keep things
> properly formatted.)
>
> Thanks,
> Richard
>
>
> gcc/
> 	* rtl.h (always_void_p): New function.
> 	* gengenrtl.c (always_void_p(: Likewise.
> 	(genmacro): Don't add a mode parameter to gen_rtx_foo if rtxes
> 	with code foo are always VOIDmode.
> 	* genemit.c (gen_exp): Update gen_rtx_foo calls accordingly.
> 	* builtins.c, caller-save.c, calls.c, cfgexpand.c, combine.c,
> 	compare-elim.c, config/aarch64/aarch64.c,
> 	config/aarch64/aarch64.md, config/alpha/alpha.c,
> 	config/alpha/alpha.md, config/arc/arc.c, config/arc/arc.md,
> 	config/arm/arm-fixed.md, config/arm/arm.c, config/arm/arm.md,
> 	config/arm/ldrdstrd.md, config/arm/thumb2.md, config/arm/vfp.md,
> 	config/avr/avr.c, config/bfin/bfin.c, config/c6x/c6x.c,
> 	config/c6x/c6x.md, config/cr16/cr16.c, config/cris/cris.c,
> 	config/cris/cris.md, config/darwin.c, config/epiphany/epiphany.c,
> 	config/epiphany/epiphany.md, config/fr30/fr30.c, config/frv/frv.c,
> 	config/frv/frv.md, config/h8300/h8300.c, config/i386/i386.c,
> 	config/i386/i386.md, config/i386/sse.md, config/ia64/ia64.c,
> 	config/ia64/vect.md, config/iq2000/iq2000.c,
> 	config/iq2000/iq2000.md, config/lm32/lm32.c, config/lm32/lm32.md,
> 	config/m32c/m32c.c, config/m32r/m32r.c, config/m68k/m68k.c,
> 	config/m68k/m68k.md, config/mcore/mcore.c, config/mcore/mcore.md,
> 	config/mep/mep.c, config/microblaze/microblaze.c,
> 	config/mips/mips.c, config/mips/mips.md, config/mmix/mmix.c,
> 	config/mn10300/mn10300.c, config/msp430/msp430.c,
> 	config/nds32/nds32-memory-manipulation.c, config/nds32/nds32.c,
> 	config/nds32/nds32.md, config/nios2/nios2.c, config/nvptx/nvptx.c,
> 	config/pa/pa.c, config/pa/pa.md, config/rl78/rl78.c,
> 	config/rs6000/altivec.md, config/rs6000/rs6000.c,
> 	config/rs6000/rs6000.md, config/rs6000/vector.md,
> 	config/rs6000/vsx.md, config/rx/rx.c, config/rx/rx.md,
> 	config/s390/s390.c, config/s390/s390.md, config/sh/sh.c,
> 	config/sh/sh.md, config/sh/sh_treg_combine.cc,
> 	config/sparc/sparc.c, config/sparc/sparc.md, config/spu/spu.c,
> 	config/spu/spu.md, config/stormy16/stormy16.c,
> 	config/tilegx/tilegx.c, config/tilegx/tilegx.md,
> 	config/tilepro/tilepro.c, config/tilepro/tilepro.md,
> 	config/v850/v850.c, config/v850/v850.md, config/vax/vax.c,
> 	config/visium/visium.c, config/xtensa/xtensa.c, cprop.c, dse.c,
> 	expr.c, gcse.c, ifcvt.c, ira.c, jump.c, lower-subreg.c,
> 	lra-constraints.c, lra-eliminations.c, lra.c, postreload.c, ree.c,
> 	reg-stack.c, reload.c, reload1.c, reorg.c, sel-sched.c,
> 	var-tracking.c: Update gen_rtx_SET calls accordingly.
>

Hi Richard,

this patch (r222882 is fine, r222883 fails) breaks bootstrap for me on 
x86_64-linux-gnu:

libtool: compile: 
/home/fsirl/BUILD/gcc-6.0.0-r222903/obj-x86_64-suse-linux/./gcc/xgcc 
-B/home/fsirl/BUILD/gcc-6.0.0-r222903/obj-x86_64-suse-linux/./gcc/ 
-B/usr/x86_64-suse-linux/bin/ -B/
usr/x86_64-suse-linux/lib/ -isystem /usr/x86_64-suse-linux/include 
-isystem /usr/x86_64-suse-linux/sys-include -DHAVE_CONFIG_H -I. 
-I../../../../libmpx/mpxwrap -I.. -fcheck-pointer-bounds
-mmpx -fno-chkp-check-read -fno-chkp-check-write -fno-chkp-use-wrappers 
-fPIC -O2 -g -fmessage-length=0 -D_FORTIFY_SOURCE=2 -funwind-tables 
-fasynchronous-unwind-tables -U_FORTIFY_SOURCE -
c ../../../../libmpx/mpxwrap/mpx_wrappers.c  -fPIC -DPIC -o 
.libs/libmpxwrappers_la-mpx_wrappers.o
../../../../libmpx/mpxwrap/mpx_wrappers.c: In function 
‘__mpx_wrapper_memmove.chkp’:
../../../../libmpx/mpxwrap/mpx_wrappers.c:160:1: error: unrecognizable insn:
  }
  ^
(insn 175 174 176 15 (parallel [
             (set (reg:BND64 175 [ __bound_tmp.21 ])
                 (unspec:BND64 [
                         (mem:DI (unspec:DI [
                                     (reg/v/f:DI 158 [ s ])
                                     (reg/f:DI 159 [ D.3339 ])
                                 ] UNSPEC_BNDLDX_ADDR) [0  S8 A8])
                     ] UNSPEC_BNDLDX))
             (use (mem:BLK (reg/v/f:DI 158 [ s ]) [0  A8]))
         ]) -1
      (nil))
../../../../libmpx/mpxwrap/mpx_wrappers.c:160:1: internal compiler 
error: in extract_insn, at recog.c:2341
0x982ee5 _fatal_insn(char const*, rtx_def const*, char const*, int, char 
const*)
         ../../gcc/rtl-error.c:110
0x982f23 _fatal_insn_not_found(rtx_def const*, char const*, int, char 
const*)
         ../../gcc/rtl-error.c:118
0x933b92 extract_insn(rtx_insn*)
         ../../gcc/recog.c:2341
0x6c09bf instantiate_virtual_regs_in_insn
         ../../gcc/function.c:1598
0x6c1273 instantiate_virtual_regs
         ../../gcc/function.c:1966
0x6c1304 execute
         ../../gcc/function.c:2015

Franz.