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* slightly optimized ppc jumptable code (one compare+jump replaced

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by a subtraction)

git-svn-id: trunk@8283 -
This commit is contained in:
Jonas Maebe 2007-08-14 14:17:09 +00:00
parent 3a7ad5212d
commit eec25e454d
1 changed files with 12 additions and 9 deletions
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21
compiler/ppcgen/ngppcset.pas
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@ -101,19 +101,23 @@ implementation
end;
begin
if not(jumptable_no_range) then
begin
{ case expr less than min_ => goto elselabel }
cg.a_cmp_const_reg_label(current_asmdata.CurrAsmList,opsize,jmp_lt,aint(min_),hregister,elselabel);
{ case expr greater than max_ => goto elselabel }
cg.a_cmp_const_reg_label(current_asmdata.CurrAsmList,opsize,jmp_gt,aint(max_),hregister,elselabel);
end;
current_asmdata.getjumplabel(table);
last:=min_;
{ make it a 32bit register }
// allocate base and index registers register
indexreg:= cg.makeregsize(current_asmdata.CurrAsmList, hregister, OS_INT);
{ indexreg := hregister; }
cg.a_load_reg_reg(current_asmdata.CurrAsmList, opsize, OS_INT, hregister, indexreg);
if not(jumptable_no_range) then
begin
{ use aword(value-min)<aword(max-min) instead of two comparisons }
{ case expr outside min_ .. max_ => goto elselabel }
cg.a_op_const_reg(current_asmdata.CurrAsmList,OP_SUB,OS_INT,aint(min_),indexreg);
{ this trick requires an unsigned comparison in all cases }
cg.a_cmp_const_reg_label(current_asmdata.CurrAsmList,OS_INT,OC_A,aint(max_)-aint(min_),indexreg,elselabel);
{ already taken into account now }
min_:=0;
end;
current_asmdata.getjumplabel(table);
{ create reference, indexreg := indexreg * sizeof(OS_ADDR) }
cg.a_op_const_reg(current_asmdata.CurrAsmList, OP_MUL, OS_INT, tcgsize2size[OS_ADDR], indexreg);
reference_reset_symbol(href, table, (-aint(min_)) * tcgsize2size[OS_ADDR]);
@ -127,7 +131,6 @@ implementation
{ generate jump table }
new_section(current_procinfo.aktlocaldata,sec_rodata,current_procinfo.procdef.mangledname,sizeof(aint));
current_procinfo.aktlocaldata.concat(Tai_label.Create(table));
last:=min_;
genitem(current_procinfo.aktlocaldata,hp);
end;