I wonder if it easily run some optimization more than wanted. GCC is not
copy-propagating anything for -O0.
BTW, iirc, currently, wgen/vho is running GTABLE, which effectively remove
some unreachable code.
Regards,
Yiran
On Tue, Dec 6, 2011 at 9:27 PM, Jian-Xin Lai <laij...@gmail.com> wrote:
> WGEN is not supposed to be an "optimization" phase. For the given
> phase, VHO might be a good place to eliminate the unreachable case
> when lowering the switch.
>
> 2011/12/7 Yiran Wang <yiran.w...@gmail.com>:
> > I am not a gatekeeper, but excuse me, I wonder if why not do such kind of
> > stuff with WGEN.
> >
> > Regards,
> > Yiran
> >
> >
> > On Tue, Dec 6, 2011 at 6:53 PM, Gang Yu <yugang...@gmail.com> wrote:
> >>
> >> Hi,
> >>
> >> Could a gatekeeper please help review the fix for
> >> bug798(http://bugs.open64.net/show_bug.cgi?id=798)?
> >>
> >> This is a bug for a long time, a typical bug case below:
> >>
> >> int defined_fun()
> >> {
> >> }
> >>
> >> int main()
> >> {
> >>
> >> int t;
> >> switch(sizeof(t))
> >> {
> >> case 4:
> >> defined_fun();
> >> break;
> >> default:
> >> undefined_fun();
> >> }
> >> }
> >>
> >> opencc -O0 b.c
> >> /tmp/cco.c7KVi5: In function `main':
> >> b.c:15: undefined reference to `undefined_fun'
> >>
> >> open64 does not invoke wopt at O0, so call to undefined_fun() is not
> >> deleted, then the linker asserts. We may have many methods to solve this
> >> issue, hacking wgen to cut down the unreachable branch, adding
> special dce
> >> phase before CG expansion ..... , but the simplest way is to invoke
> limited
> >> wopt functionality at O0.
> >>
> >> This is inspired by Fred Chow and Previously Sun Chan and Suneel Jain's
> >> comment on bug588.
> >>
> >> >My recommendation would be to do this kind of dead code
> >> >elimination at -O0 in Open64. That will provide greater compatibility
> >> >with gcc.
> >> >- Suneel
> >>
> >> >can you do an experiment, please use the following options "-O0
> >> >-phase:p" and see if the compile will go through.
> >> >Thx!
> >> >Sun
> >>
> >> We introduce a special phase q to backend, indicating invoke preopt for
> >> dce only. the Suggest patch below:
> >>
> >> osprey/be/be/driver.cxx -- 207cd21..22e93a8 100644
> >> --- a/osprey/be/be/driver.cxx
> >> +++ b/osprey/be/be/driver.cxx
> >> @@ -441,6 +441,7 @@ load_components (INT argc, char **argv)
> >> INT phase_argc;
> >> char **phase_argv;
> >> +
> >> if (!(Run_lno || Run_wopt || Run_preopt || Run_cg ||
> >> Run_prompf || Run_w2c || Run_w2f
> >> || Run_w2fc_early || Run_ipl))
> >> @@ -468,6 +469,10 @@ load_components (INT argc, char **argv)
> >> CG_Process_Command_Line (phase_argc, phase_argv, argc, argv);
> >> }
> >> + /* run preopt for dce only also invoke preopt */
> >> + if (Run_preopt_dceonly)
> >> + Run_preopt = TRUE;
> >> +
> >> if (Run_wopt || Run_preopt || Run_lno || Run_autopar) {
> >> Get_Phase_Args (PHASE_WOPT, &phase_argc, &phase_argv);
> >> #if !defined(BUILD_FAST_BIN)
> >> osprey/be/be/driver_util.cxx -- e8f58f9..d5c4698 100644
> >> --- a/osprey/be/be/driver_util.cxx
> >> +++ b/osprey/be/be/driver_util.cxx
> >> @@ -481,6 +481,12 @@ Process_Command_Line (INT argc, char **argv)
> >> if (strcmp (myname, "preopt") == 0)
> >> Run_preopt = TRUE;
> >> break;
> >> + case 'q':
> >> + if (strcmp (myname, "preopt") == 0) {
> >> + Run_preopt = TRUE;
> >> + Run_preopt_dceonly = TRUE;
> >> + }
> >> + break;
> >> case 'c':
> >> if (strcmp (myname, "cg") == 0)
> >> Run_cg = TRUE;
> >> osprey/be/opt/opt_main.cxx -- 4b8957c..a7e4679 100644
> >> --- a/osprey/be/opt/opt_main.cxx
> >> +++ b/osprey/be/opt/opt_main.cxx
> >> @@ -731,6 +731,51 @@ private:
> >> WOPT_Enable_Combine_Operations = FALSE;
> >> WOPT_Enable_SLT = FALSE;
> >> OPT_Enable_WHIRL_SSA = FALSE;
> >> + if (Run_preopt_dceonly) {
> >> + WOPT_Enable_Add_Do_Loop_Info =
> >> + WOPT_Enable_Add_Label_Loop_Info =
> >> + WOPT_Enable_Aggressive_dce =
> >> + WOPT_Enable_Aggressive_Code_Motion =
> >> + WOPT_Enable_Alias_Classification =
> >> + WOPT_Enable_Alias_Class_Fortran_Rule =
> >> + WOPT_Enable_Combine_Operations =
> >> + WOPT_Enable_Compare_Simp =
> >> + WOPT_Enable_CRSIMP =
> >> + WOPT_Enable_DCE_Alias =
> >> + WOPT_Enable_Edge_Placement =
> >> + WOPT_Enable_Exp_PRE =
> >> + WOPT_Enable_Fold2const =
> >> + WOPT_Enable_LNO_Copy_Propagate =
> >> + WOPT_Enable_FSA =
> >> + WOPT_Enable_Goto =
> >> + WOPT_Enable_Input_Prop =
> >> + WOPT_Enable_Itself_Prop =
> >> + WOPT_Enable_Ivar_Common =
> >> + WOPT_Enable_IVE =
> >> + WOPT_Enable_IVR =
> >> + WOPT_Enable_Ldx =
> >> + WOPT_Enable_Load_PRE =
> >> + WOPT_Enable_Local_Rvi =
> >> + WOPT_Enable_Output_Copy =
> >> + WOPT_Enable_Parm =
> >> + WOPT_Enable_Phi_Simp =
> >> + WOPT_Enable_RVI =
> >> + WOPT_Enable_SLT =
> >> + WOPT_Enable_Store_PRE =
> >> + WOPT_Enable_SSA_PRE =
> >> + WOPT_Enable_Vsym_Unique =
> >> + OPT_Enable_WHIRL_SSA =
> >> + WOPT_Enable_WOVP =
> >> + Enable_WN_Simp = // disable WHIRL
> >> simplifier
> >> + // WOPT_Enable_Zero_Version =
> >> + WOPT_Enable_Tail_Recur =
> >> + FALSE;
> >> +
> >> + WOPT_Enable_Verify = 1;
> >> + WOPT_Enable_DCE = WOPT_Enable_Copy_Propagate = TRUE;
> >> +
> >> +
> >> + }
> >> break;
> >> } // switch
> >> WOPT_Enable_Ldx = Indexed_Loads_Allowed;
> >> osprey/common/com/config.cxx -- c972676..387f9c1 100644
> >> --- a/osprey/common/com/config.cxx
> >> +++ b/osprey/common/com/config.cxx
> >> @@ -621,6 +621,8 @@ static OPTION_DESC Options_PHASE[] = {
> >> &Run_wopt, NULL},
> >> { OVK_BOOL, OV_INTERNAL, FALSE, "preopt", "p", 0, 0,
> 0,
> >> &Run_preopt, NULL},
> >> + { OVK_BOOL, OV_INTERNAL, FALSE, "q", "", 0, 0,
> 0,
> >> + &Run_preopt_dceonly, NULL},
> >> { OVK_BOOL, OV_INTERNAL, FALSE, "cg", "c", 0, 0,
> 0,
> >> &Run_cg, NULL},
> >> { OVK_BOOL, OV_INTERNAL, FALSE, "clist", NULL, 0, 0,
> 0,
> >> @@ -998,6 +1000,7 @@ BOOL Enable_EBO_Post_Proc_Rgn = TRUE ;
> >> BOOL Run_lno = FALSE; /* run loop-nest optimizer */
> >> BOOL Run_wopt = FALSE; /* run WHIRL global optimizer */
> >> BOOL Run_preopt = FALSE; /* run WHIRL preopt optimizer */
> >> +BOOL Run_preopt_dceonly = FALSE; /* run WHIRL preopt only for
> dce
> >> */
> >> BOOL Run_ipl = FALSE; /* run procedure summary phase */
> >> BOOL Run_cg = FALSE; /* run code generator */
> >> BOOL Run_w2c = FALSE; /* run whirl2c */
> >> osprey/common/com/config.h -- 3df7f78..9bdab1d 100644
> >> --- a/osprey/common/com/config.h
> >> +++ b/osprey/common/com/config.h
> >> @@ -732,6 +732,7 @@ extern BOOL Run_lego; /* run
> >> lego-lowering */
> >> extern BOOL Run_lego_given; /* was run lego-lowering given/not
> */
> >> extern BOOL Run_wopt; /* run WHIRL global optimizer */
> >> extern BOOL Run_preopt; /* run WHIRL preopt
> optimizer
> >> */
> >> +extern BOOL Run_preopt_dceonly; /* run WHIRL preopt only for dce */
> >> extern BOOL Run_cg; /* run code generator */
> >> extern BOOL Run_w2c; /* run whirl2c */
> >> extern BOOL Run_w2f; /* run whirl2f */
> >> osprey/driver/special_options.c -- a65a384..abe35f5 100644
> >> --- a/osprey/driver/special_options.c
> >> +++ b/osprey/driver/special_options.c
> >> @@ -416,13 +416,19 @@ add_special_options (void)
> >> *
> >> * -O0/-O1 -O2 -O3
> >> * ===========================
> >> - * .B,.I,.P: cg wopt/cg
> >> lno/wopt/cg
> >> - * .N: cg wopt/cg wopt/cg
> >> + * .B,.I: q/cg wopt/cg
> >> lno/wopt/cg
> >> + * .P: cg wopt/cg
> >> lno/wopt/cg
> >> + * .N: q/cg wopt/cg wopt/cg
> >> * .O: cg cg cg
> >> + * q means preopt for dce only.
> >> */
> >> if (source_kind == S_O)
> >> warning("compiles of WOPT-generated .O files will
> usually
> >> fail due to missing state information");
> >> if (olevel <= 1 || source_kind == S_O)
> >> + if ( source_kind != S_P )
> >> + /* bug798 open64.net. add phase q for DCE on O0 .I .B*/
> >> + flag = add_string_option(O_PHASE_, "q:c");
> >> + else
> >> flag = add_string_option(O_PHASE_, "c");
> >> else if (olevel == 2 || source_kind == S_N)
> >> flag = add_string_option(O_PHASE_, "w:c");
> >>
> >> could a gatekeeper pleae help a review? thanks
> >>
> >>
> >> Regards
> >> Gang
> >>
> >>
> >>
> ------------------------------------------------------------------------------
> >> Cloud Services Checklist: Pricing and Packaging Optimization
> >> This white paper is intended to serve as a reference, checklist and
> point
> >> of
> >> discussion for anyone considering optimizing the pricing and packaging
> >> model
> >> of a cloud services business. Read Now!
> >> http://www.accelacomm.com/jaw/sfnl/114/51491232/
> >> _______________________________________________
> >> Open64-devel mailing list
> >> Open64-devel@lists.sourceforge.net
> >> https://lists.sourceforge.net/lists/listinfo/open64-devel
> >>
> >
> >
> >
> ------------------------------------------------------------------------------
> > Cloud Services Checklist: Pricing and Packaging Optimization
> > This white paper is intended to serve as a reference, checklist and
> point of
> > discussion for anyone considering optimizing the pricing and packaging
> model
> > of a cloud services business. Read Now!
> > http://www.accelacomm.com/jaw/sfnl/114/51491232/
> > _______________________________________________
> > Open64-devel mailing list
> > Open64-devel@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/open64-devel
> >
>
>
>
> --
> Regards,
> Lai Jian-Xin
>
------------------------------------------------------------------------------
Cloud Services Checklist: Pricing and Packaging Optimization
This white paper is intended to serve as a reference, checklist and point of
discussion for anyone considering optimizing the pricing and packaging model
of a cloud services business. Read Now!
http://www.accelacomm.com/jaw/sfnl/114/51491232/
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