thx for pointing this out, it could cause problem for automatic bug triaging. Sun
On Tue, Jan 10, 2012 at 1:34 AM, Ye, Mei <mei...@amd.com> wrote: > I don't have objection to this fix. But this bug exposes a design problem in > DCE, i.e., > DCE can't handle a situation where copy prop is disabled upstream. > > -Mei > > -----Original Message----- > From: Sun Chan [mailto:sun.c...@gmail.com] > Sent: Friday, January 06, 2012 9:55 PM > To: Gang Yu > Cc: open64-devel > Subject: Re: [Open64-devel] Review request for fix bug787[WOPT] > > this fix looks better. i am still a bit worry about regressions > (performance). Have you checked perf regression with this change? > Sun > > On Sat, Jan 7, 2012 at 1:36 PM, Gang Yu <yugang...@gmail.com> wrote: >> Hi, >> >> I have a new fix for the bug787, the cut-down case from Rao(thanks) is as >> follows: >> >> extern int main(int argc) >> { >> int res1; >> int val0,val1; >> val1=100; >> if(1) >> { >> asm("bswapl %0" : "=r" (val0) : "0" (val1)); >> res1=val0; >> } >> val0=res1; >> asm("bswapl %0" : "=r" (val1) : "0" (val0)); >> } /* main */ >> analysis: >> >> Current open64 disallows copy propagation into ASM_INPUT for the var and >> ivar cases, this is reasonable since some constraints do only allow the >> parameter in specific form. >> >> If we fix following Rao's suggested way, i.e, mark some identity assignment >> undeletable for DCE, then we need special marking work for the identity >> assignment. >> >> a sound way as RAO suggested is say if the LHS of the identity assignment >> has flag CR_DONT_PROP, we disable deleting this identiy assign. However, >> this triggers the problem that other identity assign also undeletable only >> if its LHS has CR_DONT_PROP, so bug882 thrown out and it is hard to patch >> again for this special handling, this changes the default verifycation >> and DCE behavior. >> >> My suggested way is that we try propagate to a var inside ASM_INPUT, if the >> propagated expr is also a var, we allow this propagation. in the above case >> >>>LINE 13___ >>> LDID I4 I4 sym5v3 0 ty=402 <u=2 cr13> flags:0x8 b=-1 #res1 >>>OPR_STID I4 I4 sym4v4 0 <u=0 cr15> b=-1 flags:0x2 pj2 Sid-1 >> chi <> 0x0x80e1e40 >>>LINE 14___ >> mu<9/cr14 > >>> LDID I4 I4 sym4v4 0 ty=402 <u=0 cr15> flags:0x0 b=-1 #val0 >>> ASM_INPUT opnd:1 <u=0 cr16> isop_flags:0xc0000 flags:0x0 b=E1 >>> ASM_STMT <u=0 cr17> isop_flags:0xc0000 flags:0x0 b=-1 >>>OPR_ASM_STMT b=-1 flags:0x2 pj2 Sid-1 >> sym5v3 is propagated into OPR_ASMINPUT. >> >> The patch below: >> >> --- a/osprey/be/opt/opt_prop.cxx >> +++ b/osprey/be/opt/opt_prop.cxx >> @@ -1504,9 +1504,23 @@ COPYPROP::Copy_propagate_cr(CODEREP *x, BB_NODE >> *curbb, >> expr = Copy_propagate_cr(x->Opnd(i), curbb, inside_cse, in_array); >> else { >> // OSP_384 >> - if(opr == OPR_ASM_INPUT) >> - x->Opnd(i)->Set_flag(CF_DONT_PROP); >> - expr = NULL; >> + if(opr == OPR_ASM_INPUT) { >> + // open64.net bug787. Try propagate for VAR first, if the >> propagated expr is the same >> + // kind to the original one,i.e, also a VAR. we allow this >> propagation. otherwise, disable it. >> + if ( x->Opnd(i)->Kind() == CK_VAR ) { >> + CODEREP *possible_prop = Copy_propagate_cr(x->Opnd(i), curbb, >> inside_cse, in_array); >> + if (possible_prop && possible_prop->Kind() == >> x->Opnd(i)->Kind()) >> + expr = possible_prop; >> + else { >> + x->Opnd(i)->Set_flag(CF_DONT_PROP); >> + expr = NULL; >> + } >> + } >> + else { >> + x->Opnd(i)->Set_flag(CF_DONT_PROP); >> + expr = NULL; >> + } >> + } >> } >> #else >> please gatekeeper help a review >> >> Thanks. >> >> Regards >> Gang >> >> ------------------------------------------------------------------------------ >> Ridiculously easy VDI. With Citrix VDI-in-a-Box, you don't need a complex >> infrastructure or vast IT resources to deliver seamless, secure access to >> virtual desktops. With this all-in-one solution, easily deploy virtual >> desktops for less than the cost of PCs and save 60% on VDI infrastructure >> costs. Try it free! http://p.sf.net/sfu/Citrix-VDIinabox >> _______________________________________________ >> Open64-devel mailing list >> Open64-devel@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/open64-devel >> > > ------------------------------------------------------------------------------ > Ridiculously easy VDI. With Citrix VDI-in-a-Box, you don't need a complex > infrastructure or vast IT resources to deliver seamless, secure access to > virtual desktops. With this all-in-one solution, easily deploy virtual > desktops for less than the cost of PCs and save 60% on VDI infrastructure > costs. Try it free! http://p.sf.net/sfu/Citrix-VDIinabox > _______________________________________________ > Open64-devel mailing list > Open64-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/open64-devel > > ------------------------------------------------------------------------------ Write once. Port to many. Get the SDK and tools to simplify cross-platform app development. Create new or port existing apps to sell to consumers worldwide. Explore the Intel AppUpSM program developer opportunity. appdeveloper.intel.com/join http://p.sf.net/sfu/intel-appdev _______________________________________________ Open64-devel mailing list Open64-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/open64-devel
