On Fri, Apr 20, 2012 at 2:38 PM, Sun Chan <sun.c...@gmail.com> wrote:
> It is one thing to allow FE to generate temps with special substring.
> It it another to assume that special substring always mean compiler
> generated temps. They are not logically equivalent.
> Sun
Maybe I do not make things clear in my last post. Now, I will put more
details.
The source code in wgen_spin_symbol.cxx
1569ST*
1570Create_ST_For_Tree (gs_t decl_node)
1571{
1572 TY_IDX ty_idx;
1573 ST* st = NULL;
1574 char *name;
1575 char tempname[32];
1595 if (gs_tree_code(decl_node) == GS_RESULT_DECL) {
1596 sprintf(tempname, ".result_decl_%d", gs_decl_uid(decl_node));
1597 name = tempname;
1598 }
1599 else if ((gs_tree_code(decl_node) == GS_FUNCTION_DECL ||
1600 gs_tree_code(decl_node) == GS_PARM_DECL ||
1601 (gs_tree_code(decl_node) == GS_VAR_DECL &&
1602 gs_decl_asmreg(decl_node) >= 0)) &&
1603 gs_decl_name(decl_node) != 0)
1604 name = (char *) gs_identifier_pointer (gs_decl_name (decl_node));
1605 else if (gs_decl_assembler_name (decl_node) && gs_decl_name
(decl_node))
1606 name = (char *) gs_identifier_pointer (gs_decl_assembler_name
(decl_node));
1607 else if (gs_decl_name (decl_node))
1608 name = (char *) gs_identifier_pointer (gs_decl_name (decl_node));
1609 else {
1610 sprintf(tempname, "anon%d", ++anon_count);
1611 name = tempname;
1612 }
...
when control goes here, we could say the compiler generate temp var in two
cases. line 1595-1598 and line 1609-1612, i.e, the green part. common part
"name = tempname" can be used as the indicate.
We just only want to set the temp var to SCLASS_AUTO for those generated in
"else" part, i.e, 1609-1612, these names contains "anon", without other
flag to indicate, we just use this name prefix. So, we can have the
following change:
1777 if (name != tempname || strncmp(tempname,"anon",4)) { *//
Not a temp var, or temp var for result_decl, no change*
1778 sclass = SCLASS_FSTATIC;
1779 eclass = EXPORT_LOCAL;
1780 } else { *// Yes, these are temp vars we want to change*
1781 sclass = SCLASS_AUTO;
1782 eclass = EXPORT_LOCAL;
1783 }
1784 }
1785 if (name != tempname || strncmp(tempname,"anon",4))
1786 level = GLOBAL_SYMTAB;
1787 else
1788 level = CURRENT_SYMTAB;
Regards
Gang
> On Fri, Apr 20, 2012 at 2:01 PM, Gang Yu <yugang...@gmail.com> wrote:
> > Hi, Gautam
> >
> > Thanks for the review.
> >
> > You post a good questtion. In my patch, you may note
> >
> > + if (name != tempname || strncmp(tempname,"anon",4)) {
> >
> > "name != tempname" address your care.
> >
> > Walk though the wgen_spin_symbol.cxx:1611, you may note that
> >
> > 1609 else {
> > 1610 sprintf(tempname, "anon%d", ++anon_count);
> > 1611 name = tempname;
> > 1612 }
> > name == tempname indicate that this is FE generated temp var rather
> than var
> > in user program.
> > Regards
> > Gang
> >
> >
> > On Fri, Apr 20, 2012 at 1:54 PM, Gautam Chakrabarti <
> gautam.c...@yahoo.com>
> > wrote:
> >>
> >> Hi,
> >>
> >> Thanks for working on this issue. But this change is not clean. The
> change
> >> is essentially assuming special semantics based on a variable name.
> What if
> >> a user variable is named anon?
> >>
> >> -Gautam
> >>
> >> From: Gang Yu <yugang...@gmail.com>
> >> To: open64-devel <open64-devel@lists.sourceforge.net>
> >> Sent: Thursday, April 19, 2012 2:01 AM
> >> Subject: [Open64-devel] review request for fix bug965[WGEN]
> >>
> >> Hi,
> >>
> >> Could a gatekeeper please help review the fix for
> >> bug965?(http://bugs.open64.net/show_bug.cgi?id=965)
> >>
> >> This is a code-size issue for open64, i.e, the compiler generate garbage
> >> code although it still make it right.
> >>
> >> a cut-down case below:
> >>
> >> static inline __attribute__((always_inline)) int
> >> x86_this_cpu_constant_test_bit(unsigned int nr,
> >> const unsigned long *addr)
> >> {
> >> unsigned long *a = (unsigned long *)addr + nr / 64;
> >>
> >> return ((1UL << (nr % 64)) & ({ typeof(*a) pfo_ret__; switch
> (sizeof(*a))
> >> {
> >> case 1: asm("mov" "b ""%%""gs"":" "%P" "1"",%0" : "=q" (pfo_ret_\
> >> _) : "m" (*a)); break; case 2: asm("mov" "w ""%%""gs"":" "%P" "1"",%0" :
> >> "=r"
> >> (pfo_ret__) : "m" (*a)); break; case 4: asm("mov" "l ""%%""gs""\
> >> :" "%P" "1"",%0" : "=r" (pfo_ret__) : "m" (*a)); break; case 8:
> asm("mov"
> >> "q
> >> ""%%""gs"":" "%P" "1"",%0" : "=r" (pfo_ret__) : "m" (*a)); break\
> >> ; default: __bad_percpu_size(); } pfo_ret__; })) != 0;
> >> }
> >> opencc -c anon.c -keep
> >> yug@jupiter:~/work/codesize> readelf -s anon.o
> >>
> >>
> >> Symbol table '.symtab' contains 8 entries:
> >> Num: Value Size Type Bind Vis Ndx Name
> >> 4: 0000000000000000 8 OBJECT LOCAL DEFAULT 3 anon1
> >> x86_this_cpu_constant_test_bit is non-called inline keyword function, so
> >> there should generate nothing symbols in this object file, however,
> >> anon1 appears unexpected.
> >> Analysis:
> >>
> >> When we examine the WGEN code, we found that the code snipper like
> these:
> >>
> >> 1569ST*
> >> 1570Create_ST_For_Tree (gs_t decl_node)
> >> 1571{
> >> ...
> >> 1609 else {
> >> 1610 sprintf(tempname, "anon%d", ++anon_count);
> >> 1611 name = tempname;
> >> 1612 }
> >> ...
> >> 1750 if (gs_tree_public (decl_node)) {
> >> ...
> >> 1776 else {
> >> 1777 sclass = SCLASS_FSTATIC;
> >> 1778 eclass = EXPORT_LOCAL;
> >> 1779 }
> >> 1780 level = GLOBAL_SYMTAB;
> >> 1781 }
> >>
> >> this is to say, when current gs_tree is not public, we generate such a
> >> variable as File-Scope(static) global variable.
> >> However, anon1 appears as the temporary variable in a computation.
> >>
> >> U8U8LDID 0 <2,4,pfo_ret__> T<9,.predef_U8,8>
> >> U8STID 0 <1,51,anon1> T<9,.predef_U8,8> {line: 1/7}
> >> U8INTCONST 1 (0x1)
> >> I4I4LDID 0 <2,1,nr> T<4,.predef_I4,4>
> >> I4INTCONST 63 (0x3f)
> >> I4BAND
> >> U8SHL
> >> U8U8LDID 0 <1,51,anon1> T<9,.predef_U8,8>
> >> U8BAND
> >> U8INTCONST 0 (0x0)
> >> I4U8NE
> >> I4RETURN_VAL {line: 0/0}
> >> and we do find the producer for anon
> >> 1609 else {
> >> 1610 sprintf(tempname, "anon%d", ++anon_count);
> >> 1611 name = tempname;
> >> 1612 }
> >> we should make it SCLASS_AUTO in LOCAL_SYMTAB.
> >>
> >> Suggested patch:
> >> osprey/wgen/wgen_spin_symbol.cxx -- ff56fe0..b24a800 100644
> >> --- a/osprey/wgen/wgen_spin_symbol.cxx
> >> +++ b/osprey/wgen/wgen_spin_symbol.cxx
> >> @@ -1774,10 +1774,18 @@ Create_ST_For_Tree (gs_t decl_node)
> >> eclass = EXPORT_PREEMPTIBLE;
> >> }
> >> else {
> >> + if (name != tempname || strncmp(tempname,"anon",4)) {
> >> sclass = SCLASS_FSTATIC;
> >> eclass = EXPORT_LOCAL;
> >> + } else {
> >> + sclass = SCLASS_AUTO;
> >> + eclass = EXPORT_LOCAL;
> >> + }
> >> }
> >> - level = GLOBAL_SYMTAB;
> >> + if (name != tempname || strncmp(tempname,"anon",4))
> >> + level = GLOBAL_SYMTAB;
> >> + else
> >> + level = CURRENT_SYMTAB;
> >> }
> >> else {
> >> #ifdef KEY
> >>
> >> As an example, I show the codesize comparison to gcc generation and the
> >> source code in the attach, we can see this is really bad for code-size.
> >> Could a gatekeeper please help a review? thanks in advance.
> >>
> >>
> >> Regards
> >> Gang
> >>
> >>
> >>
> ------------------------------------------------------------------------------
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> >>
> >>
> >
> >
> >
> ------------------------------------------------------------------------------
> > For Developers, A Lot Can Happen In A Second.
> > Boundary is the first to Know...and Tell You.
> > Monitor Your Applications in Ultra-Fine Resolution. Try it FREE!
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>
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