From 52fcc0a407da0bc2b0a1a7edc6f90756e790c29c Mon Sep 17 00:00:00 2001
From: nickysn <nickysn@gmail.com>
Date: Sat, 28 Sep 2013 11:54:02 +0000
Subject: [PATCH] + added a new x86-specific compiler option 'enablecld', which
 controls whether   the compiler should emit a CLD before using the x86 string
 instructions.

git-svn-id: trunk@25590 -
---
 compiler/globals.pas     | 13 +++++++++++++
 compiler/i386/cgcpu.pas  |  3 ++-
 compiler/i8086/cgcpu.pas |  3 ++-
 compiler/options.pas     |  4 ++++
 compiler/x86/cgx86.pas   |  5 ++---
 5 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/compiler/globals.pas b/compiler/globals.pas
index 32f4610940..9df087d776 100644
--- a/compiler/globals.pas
+++ b/compiler/globals.pas
@@ -154,6 +154,12 @@ interface
 
          disabledircache : boolean;
 
+{$if defined(x86)}
+         { setting this to true causes the compiler to emit a CLD instruction
+           before using the x86 string instructions. }
+         enablecld       : boolean;
+{$endif defined(x86)}
+
 {$if defined(i8086)}
          x86memorymodel  : tx86memorymodel;
 {$endif defined(i8086)}
@@ -485,6 +491,13 @@ interface
         minfpconstprec : s32real;
 
         disabledircache : false;
+{$if defined(i8086)}
+        enablecld      : true;
+{$elseif defined(i386)}
+        enablecld      : true;
+{$elseif defined(x86_64)}
+        enablecld      : false;
+{$endif}
 {$if defined(i8086)}
         x86memorymodel : mm_small;
 {$endif defined(i8086)}
diff --git a/compiler/i386/cgcpu.pas b/compiler/i386/cgcpu.pas
index bbda0fbc92..84fe41438f 100644
--- a/compiler/i386/cgcpu.pas
+++ b/compiler/i386/cgcpu.pas
@@ -485,7 +485,8 @@ unit cgcpu;
             else
               list.concat(Taicpu.op_const_reg(A_IMUL,S_L,len,NR_ECX));
           end;
-        list.concat(Taicpu.op_none(A_CLD,S_NO));
+        if current_settings.enablecld then
+          list.concat(Taicpu.op_none(A_CLD,S_NO));
         list.concat(Taicpu.op_none(A_REP,S_NO));
         case opsize of
           S_B : list.concat(Taicpu.Op_none(A_MOVSB,S_NO));
diff --git a/compiler/i8086/cgcpu.pas b/compiler/i8086/cgcpu.pas
index d97b3dc950..add88cb5f2 100644
--- a/compiler/i8086/cgcpu.pas
+++ b/compiler/i8086/cgcpu.pas
@@ -1504,7 +1504,8 @@ unit cgcpu;
             else
               list.concat(Taicpu.op_const_reg(A_IMUL,S_W,len,NR_CX));
           end;
-        list.concat(Taicpu.op_none(A_CLD,S_NO));
+        if current_settings.enablecld then
+          list.concat(Taicpu.op_none(A_CLD,S_NO));
         list.concat(Taicpu.op_none(A_REP,S_NO));
         case opsize of
           S_B : list.concat(Taicpu.Op_none(A_MOVSB,S_NO));
diff --git a/compiler/options.pas b/compiler/options.pas
index 5f740bf702..779c971c30 100644
--- a/compiler/options.pas
+++ b/compiler/options.pas
@@ -3475,6 +3475,10 @@ if (target_info.abi = abi_eabihf) then
     mm_huge:    def_system_macro('FPC_MM_HUGE');
   end;
 {$endif}
+{$if defined(x86)}
+  if current_settings.enablecld then
+    def_system_macro('FPC_ENABLED_CLD');
+{$endif}
 
 
   { Section smartlinking conflicts with import sections on Windows }
diff --git a/compiler/x86/cgx86.pas b/compiler/x86/cgx86.pas
index e3f428f17a..5bfe9ae93e 100644
--- a/compiler/x86/cgx86.pas
+++ b/compiler/x86/cgx86.pas
@@ -2233,9 +2233,8 @@ unit cgx86;
               end;
 
             getcpuregister(list,REGCX);
-{$if defined(i8086) or defined(i386)}
-           list.concat(Taicpu.op_none(A_CLD,S_NO));
-{$endif i8086 or i386}
+            if current_settings.enablecld then
+              list.concat(Taicpu.op_none(A_CLD,S_NO));
             if (cs_opt_size in current_settings.optimizerswitches) and
                (len>sizeof(aint)+(sizeof(aint) div 2)) then
               begin