* fix comparedword, fixes #7143

git-svn-id: trunk@4153 -

.gitattributes

@@ -7222,6 +7222,7 @@ tests/webtbs/tw6980.pp svneol=native#text/plain
 tests/webtbs/tw6989.pp svneol=native#text/plain
 tests/webtbs/tw7006.pp svneol=native#text/plain
 tests/webtbs/tw7104.pp svneol=native#text/plain
+tests/webtbs/tw7143.pp -text
 tests/webtbs/ub1873.pp svneol=native#text/plain
 tests/webtbs/ub1883.pp svneol=native#text/plain
 tests/webtbs/uw0555.pp svneol=native#text/plain

rtl/i386/i386.inc

@@ -617,60 +617,30 @@ var
 asm
         movl    %edi,saveedi
         movl    %esi,saveesi
-        movl    %ebx,saveebx
         cld
 {$ifdef REGCALL}
         movl    %eax,%edi
         movl    %edx,%esi
-        movl    %ecx,%eax
 {$else}
-        movl    len,%eax
+        movl    len,%ecx
         movl    buf2,%esi       { Load params}
         movl    buf1,%edi
 {$endif}
-        testl   %eax,%eax       {We address -2(%esi), so we have to deal with len=0}
+        testl   %ecx,%ecx 
         je      .LCmpDwordExit
-        cmpl    $3,%eax         {<3 (3 bytes align + 4 bytes cmpsl) = 2 DWords}
-        jl      .LCmpDword2      { not worth aligning and go through all trouble}
-        movl    (%edi),%ebx     // Compare alignment bytes.
-        cmpl    (%esi),%ebx
-        jne     .LCmpDword2      // Aligning will go wrong already. Max 2 words will be scanned Branch NOW
-        shll    $2,%eax         {Convert word count to bytes}
-        movl    %edi,%edx       { Align comparing is already done, so simply add}
-        negl    %edx            { calc bytes to align  -%edi and 3}
-        andl    $3,%edx
-        addl    %edx,%esi       { Skip max 3 bytes alignment}
-        addl    %edx,%edi
-        subl    %edx,%eax       { Subtract from number of bytes to go}
-        movl    %eax,%ecx       { Make copy of bytes to go}
-        andl    $3,%eax         { Calc remainder (mod 4) }
-        shrl    $2,%ecx         { divide bytes to go by 4, DWords to go}
-        orl     %ecx,%ecx       { Sets zero flag if ecx=0 -> no cmp}
+        xorl    %eax,%eax
         rep                     { Compare entire DWords}
         cmpsl
-        je      .LCmpDword2a     { All equal? then to the left over bytes}
-        movl    $4,%eax         { Not equal. Rescan the last 4 bytes bytewise}
-        subl    %eax,%esi       { Go back one DWord}
-        subl    %eax,%edi
-        addl    $3,%eax         {if align<>0 this causes repcount to be 2}
-.LCmpDword2a:
-        subl    %edx,%esi       { Subtract alignment}
-        subl    %edx,%edi
-        addl    %edx,%eax
-        shrl    $2,%eax
-.LCmpDword2:
-        movl    %eax,%ecx       {words still to (re)scan}
-        orl     %eax,%eax       {prevent disaster in case %eax=0}
-        rep
-        cmpsl
-.LCmpDword3:
-        movzwl  -4(%esi),%ecx
-        movzwl  -4(%edi),%eax    // Compare failing (or equal) position
-        subl    %ecx,%eax        // calculate end result.
+        movl    -4(%edi),%edi        // Compare failing (or equal) position
+        subl    -4(%esi),%edi        // calculate end result.
+        setb    %dl
+        seta    %cl
+        addb    %cl,%al
+        subb    %dl,%al
+        movsbl  %al,%eax
 .LCmpDwordExit:
         movl    saveedi,%edi
         movl    saveesi,%esi
-        movl    saveebx,%ebx
 end;
 {$endif FPC_SYSTEM_HAS_COMPAREDWORD}
 

tests/webtbs/tw7143.pp

@@ -0,0 +1,18 @@
+var a,b: array[0..99] of byte;
+    i: integer;
+    c: byte;
+begin
+for i:=0 to 99 do a[i]:=i;
+b:=a;
+
+writeln('The same:',comparedword(a[0],b[0],25));
+writeln('All other results should be negative.');
+
+for i:=0 to 99 do
+  begin
+  c:=b[i];
+  b[i]:=200;
+  writeln(i:3,' ',comparedword(a[0],b[0],25));
+  b[i]:=c;
+  end;
+end.