+ added function cpubase.segment_regs_equal, which checks whether 2 segment regs are equal in the current memory model

git-svn-id: trunk@24949 -

compiler/x86/cpubase.pas

@@ -35,7 +35,7 @@ interface
 
 uses
   cutils,cclasses,
-  globtype,
+  globtype,globals,
   cgbase
   ;
 
@@ -286,6 +286,9 @@ uses
     function inverse_cond(const c: TAsmCond): TAsmCond; {$ifdef USEINLINE}inline;{$endif USEINLINE}
     function conditions_equal(const c1, c2: TAsmCond): boolean; {$ifdef USEINLINE}inline;{$endif USEINLINE}
 
+    { checks whether two segment registers are normally equal in the current memory model }
+    function segment_regs_equal(r1,r2:tregister):boolean;
+
 {$ifdef i8086}
     { returns the next virtual register }
     function GetNextReg(const r : TRegister) : TRegister;
@@ -553,6 +556,48 @@ implementation
       end;
 
 
+    function segment_regs_equal(r1, r2: tregister): boolean;
+      begin
+        if not is_segment_reg(r1) or not is_segment_reg(r2) then
+          internalerror(2013062301);
+        { every segment register is equal to itself }
+        if r1=r2 then
+          exit(true);
+{$if defined(i8086)}
+        case current_settings.x86memorymodel of
+          mm_tiny:
+            begin
+              { CS=DS=SS }
+              if ((r1=NR_CS) or (r1=NR_DS) or (r1=NR_SS)) and
+                 ((r2=NR_CS) or (r2=NR_DS) or (r2=NR_SS)) then
+                exit(true);
+              { the remaining are distinct from each other }
+              exit(false);
+            end;
+          mm_small,mm_medium:
+            begin
+              { DS=SS }
+              if ((r1=NR_DS) or (r1=NR_SS)) and
+                 ((r2=NR_DS) or (r2=NR_SS)) then
+                exit(true);
+              { the remaining are distinct from each other }
+              exit(false);
+            end;
+          mm_compact,mm_large,mm_huge: internalerror(2013062303);
+          else
+            internalerror(2013062302);
+        end;
+{$elseif defined(i386) or defined(x86_64)}
+        { DS=SS=ES }
+        if ((r1=NR_DS) or (r1=NR_SS) or (r1=NR_ES)) and
+           ((r2=NR_DS) or (r2=NR_SS) or (r2=NR_ES)) then
+          exit(true);
+        { the remaining are distinct from each other }
+        exit(false);
+{$endif}
+      end;
+
+
 {$ifdef i8086}
     function GetNextReg(const r: TRegister): TRegister;
       begin