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* use call/pop instead of call/mov/ret to get the GOT pointer on

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Darwin/i386, because that's slightly faster on Core Solo and
    later CPUs (and it avoid using a non-volatile register when not
    required)

git-svn-id: trunk@15532 -
This commit is contained in:
Jonas Maebe 2010-07-07 18:55:43 +00:00
parent c6d00a2b1f
commit 574d7eb70d
1 changed files with 24 additions and 15 deletions
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39
compiler/i386/cgcpu.pas
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@ -71,7 +71,7 @@ unit cgcpu;
uses
globals,verbose,systems,cutils,
paramgr,procinfo,fmodule,
rgcpu,rgx86;
rgcpu,rgx86,cpuinfo;
function use_push(const cgpara:tcgpara):boolean;
begin
@ -101,8 +101,6 @@ unit cgcpu;
begin
if getsupreg(current_procinfo.got) < first_int_imreg then
include(rg[R_INTREGISTER].used_in_proc,getsupreg(current_procinfo.got));
{ ebx is currently always used (do to getiepasebx call) }
include(rg[R_INTREGISTER].used_in_proc,RS_EBX);
end;
inherited do_register_allocation(list,headertai);
end;
@ -509,31 +507,42 @@ unit cgcpu;
procedure tcg386.g_maybe_got_init(list: TAsmList);
var
notdarwin: boolean;
begin
{ allocate PIC register }
if (cs_create_pic in current_settings.moduleswitches) and
(tf_pic_uses_got in target_info.flags) and
(pi_needs_got in current_procinfo.flags) then
begin
if (target_info.system<>system_i386_darwin) then
notdarwin:=(target_info.system<>system_i386_darwin);
{ on darwin, the got register is virtual (and allocated earlier
already) }
if notdarwin then
{ ecx could be used in leaf procedures that don't use ecx to pass
aparameter }
current_procinfo.got:=NR_EBX;
if notdarwin { needs testing before it can be enabled for non-darwin platforms
and
(current_settings.optimizecputype in [cpu_Pentium2,cpu_Pentium3,cpu_Pentium4]) } then
begin
current_module.requires_ebx_pic_helper:=true;
cg.a_call_name_static(list,'fpc_geteipasebx');
list.concat(taicpu.op_sym_ofs_reg(A_ADD,S_L,current_asmdata.RefAsmSymbol('_GLOBAL_OFFSET_TABLE_'),0,NR_PIC_OFFSET_REG));
list.concat(tai_regalloc.alloc(NR_PIC_OFFSET_REG,nil));
{ ecx could be used in leaf procedures }
current_procinfo.got:=NR_EBX;
end
else
begin
{ can't use ecx, since that one may overwrite a parameter }
current_module.requires_ebx_pic_helper:=true;
cg.a_call_name_static(list,'fpc_geteipasebx');
list.concat(tai_regalloc.alloc(NR_EBX,nil));
{ call/pop is faster than call/ret/mov on Core Solo and later
according to Apple's benchmarking -- and all Intel Macs
have at least a Core Solo (furthermore, the i386 - Pentium 1
don't have a return stack buffer) }
a_call_name_static(list,current_procinfo.CurrGOTLabel.name);
a_label(list,current_procinfo.CurrGotLabel);
{ got is already set by ti386procinfo.allocate_got_register }
list.concat(tai_regalloc.dealloc(NR_EBX,nil));
a_load_reg_reg(list,OS_ADDR,OS_ADDR,NR_EBX,current_procinfo.got);
list.concat(taicpu.op_reg(A_POP,S_L,current_procinfo.got))
end;
if notdarwin then
begin
list.concat(taicpu.op_sym_ofs_reg(A_ADD,S_L,current_asmdata.RefAsmSymbol('_GLOBAL_OFFSET_TABLE_'),0,NR_PIC_OFFSET_REG));
list.concat(tai_regalloc.alloc(NR_PIC_OFFSET_REG,nil));
end;
end;
end;