Fix bugs with several operations on negative values of type signed char.

The basic issue with all of these is that they failed to sign-extend the 8-bit signed char value to the full 16-bit A register. This could make certain operations on negative signed char values appear to yield positive values outside the range of signed char.

The following example code demonstrates the problems:

#include <stdio.h>
signed char f(void) {return -50;}
int main(void) {
        long l = -123;
        int i = -99;
        signed char sc = -47;
        signed char *scp = &sc;
        printf("%i\n", (signed char)l);
        printf("%i\n", (signed char)i);
        printf("%i\n", f());
        printf("%i\n", (*scp)++);
        printf("%i\n", *scp = -32);
}

Gen.pas

@@ -1251,15 +1251,23 @@ else if op^.q in [ubyteToLong,ubyteToUlong,uwordToLong,uwordToUlong] then
       GenImplied(m_pha);
       end; {else}
    end {else if}
-else if op^.q in [wordToByte,wordToUbyte,uwordToByte,uwordToUbyte] then
+else if op^.q in [wordToUbyte,uwordToUbyte] then
    GenNative(m_and_imm, immediate, $00FF, nil, 0)
+else if op^.q in [wordToByte,uwordToByte] then begin
+   lab1 := GenLabel;
+   GenNative(m_and_imm, immediate, $00FF, nil, 0);
+   GenNative(m_bit_imm, immediate, $0080, nil, 0);
+   GenNative(m_beq, relative, lab1, nil, 0);
+   GenNative(m_ora_imm, immediate, $FF00, nil, 0);
+   GenLab(lab1);
+   end {else if}
 else if op^.q in [byteToReal,uByteToReal,wordToReal] then
    GenCall(11)
 else if op^.q = uwordToReal then begin
    GenNative(m_ldx_imm, immediate, 0, nil, 0);
    GenCall(12);
    end {else if}
-else if op^.q in [longToByte,longToUbyte,ulongToByte,ulongToUbyte] then begin
+else if op^.q in [longToUbyte,ulongToUbyte] then begin
    if gLong.where = A_X then
       GenNative(m_and_imm, immediate, $00FF, nil, 0)
    else if gLong.where = constant then
@@ -1270,6 +1278,22 @@ else if op^.q in [longToByte,longToUbyte,ulongToByte,ulongToUbyte] then begin
       GenNative(m_and_imm, immediate, $00FF, nil, 0);
       end; {else if}
    end {else if}
+else if op^.q in [longToByte,ulongToByte] then begin
+   if gLong.where = A_X then
+      GenNative(m_and_imm, immediate, $00FF, nil, 0)
+   else if gLong.where = constant then
+      GenNative(m_lda_imm, immediate, long(gLong.lval).lsw & $00FF, nil, 0)
+   else {if gLong.where = onStack then} begin
+      GenImplied(m_pla);
+      GenImplied(m_plx);
+      GenNative(m_and_imm, immediate, $00FF, nil, 0);
+      end; {else if}
+   lab1 := GenLabel;
+   GenNative(m_bit_imm, immediate, $0080, nil, 0);
+   GenNative(m_beq, relative, lab1, nil, 0);
+   GenNative(m_ora_imm, immediate, $FF00, nil, 0);
+   GenLab(lab1);
+   end {else if}
 else if op^.q in [longToWord,longToUword,ulongToWord,ulongToUword] then begin
    {Note: if the result is in A_X, no further action is needed}
    if gLong.where = constant then
@@ -1983,8 +2007,16 @@ case op^.optype of
             GenNative(m_rep, immediate, 32, nil, 0);
          end; {else}
       if not skipLoad then
-         if short then
+         if short then begin
             GenNative(m_and_imm, immediate, $00FF, nil, 0);
+            if op^.optype = cgByte then begin
+               GenNative(m_bit_imm, immediate, $0080, nil, 0);
+               lab1 := GenLabel;
+               GenNative(m_beq, relative, lab1, nil, 0);
+               GenNative(m_ora_imm, immediate, $FF00, nil, 0);
+               GenLab(lab1);
+               end; {if}
+            end; {if}
       end; {case cgByte,cgUByte,cgWord,cgUWord}
 
    otherwise:
@@ -3225,6 +3257,7 @@ var
    simple: boolean;			{is the load a simple load?}
    lLong: longType;			{address record for left node}
    zero: boolean;			{is the operand a constant zero?}
+   lab1: integer;			{label}
 
 
    procedure LoadLSW;
@@ -3538,8 +3571,16 @@ case optype of
          end; {else}
       if short then begin
          GenNative(m_rep, immediate, 32, nil, 0);
-         if opcode = pc_cpi then
+         if opcode = pc_cpi then begin
             GenNative(m_and_imm, immediate, $00FF, nil, 0);
+            if optype = cgByte then begin
+               GenNative(m_bit_imm, immediate, $0080, nil, 0);
+               lab1 := GenLabel;
+               GenNative(m_beq, relative, lab1, nil, 0);
+               GenNative(m_ora_imm, immediate, $FF00, nil, 0);
+               GenLab(lab1);
+               end; {if}
+            end; {if}
          end; {if}
       end; {case cgByte,cgUByte,cgWord,cgUWord}
 
@@ -5124,6 +5165,7 @@ procedure GenTree {op: icptr};
 
    var
       size: integer;			{localSize + parameterSize}
+      lab1: integer;			{label}
 
    begin {GenRet}
    {pop the name record}
@@ -5172,7 +5214,14 @@ procedure GenTree {op: icptr};
 
       cgByte,cgUByte: begin
          GenNative(m_lda_dir, direct, funLoc, nil, 0);
-         GenNative(m_and_imm, immediate, $00FF, nil, 0);
+         GenNative(m_and_imm, immediate, $00FF, nil, 0);         
+         if op^.optype = cgByte then begin
+            GenNative(m_bit_imm, immediate, $0080, nil, 0);
+            lab1 := GenLabel;
+            GenNative(m_beq, relative, lab1, nil, 0);
+            GenNative(m_ora_imm, immediate, $FF00, nil, 0);
+            GenLab(lab1);
+            end; {if}
          if size <> 2 then
             GenImplied(m_tay);
          end;