* make use of xor reg,reg by generating it directly instead of hoping for the peephole

  optimizer which cannot do this properly due to missing information about flags. By doing
  so the size of the compiler executable gets reduced by ~1 %

git-svn-id: trunk@33524 -

compiler/i386/popt386.pas

@@ -453,16 +453,6 @@ begin
                           hp1.free;
                         end;
                 end;
-              A_XOR:
-                if (taicpu(p).oper[0]^.typ = top_reg) and
-                   (taicpu(p).oper[1]^.typ = top_reg) and
-                   (taicpu(p).oper[0]^.reg = taicpu(p).oper[1]^.reg) then
-                 { temporarily change this to 'mov reg,0' to make it easier }
-                 { for the CSE. Will be changed back in pass 2              }
-                  begin
-                    taicpu(p).opcode := A_MOV;
-                    taicpu(p).loadConst(0,0);
-                  end;
             end;
           end;
       end;

compiler/x86/cgx86.pas

@@ -909,9 +909,10 @@ unit cgx86;
 
       begin
         check_register_size(tosize,reg);
-        { the optimizer will change it to "xor reg,reg" when loading zero, }
-        { no need to do it here too (JM)                                   }
-        list.concat(taicpu.op_const_reg(A_MOV,TCGSize2OpSize[tosize],a,reg))
+        if a=0 then
+          list.concat(taicpu.op_reg_reg(A_XOR,TCGSize2OpSize[tosize],reg,reg))
+        else
+          list.concat(taicpu.op_const_reg(A_MOV,TCGSize2OpSize[tosize],a,reg));
       end;