Fix bug in some cases where a byte value is loaded and then stored as a word.

It could wind up storing garbage in the upper 8 bits of the destination, because it was not doing a proper 8-bit to 16-bit conversion.

This is an old bug, but the change in commit 95f5182442 caused it to be triggered in more cases, e.g. in the C7.5.1.1.CC test case.

Here is a case that could exhibit the bug even before that:

#pragma optimize 1
#include <stdio.h>
int main(void) {
        int k[1];
        int i = 0;
        unsigned char uch = 'm';
        k[i] = uch;
        printf("%i\n", k[0]);
}

Gen.pas

@@ -4278,6 +4278,18 @@ var
                GenNative(m_lda_abs, absolute, q, lab, 0)
             else
                GenNative(m_lda_long, longabsolute, q, lab, 0);
+      if not short then
+         if op^.right^.optype in [cgByte,cgUByte] then
+            if op^.right^.opcode <> pc_ldc 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} 
    else begin
       GenImplied(m_pla);

cc.notes

@@ -1213,6 +1213,8 @@ int foo(int[42]);
 
 161. The system() function might return the wrong value when using the large memory model.  (This was a regression introduced in ORCA/C 2.2.0 B3.)
 
+162. In certain cases, an assignment from a location with an 8-bit type to a location with a 16-bit type might store the wrong value.
+
 -- Bugs from C 2.1.0 that have been fixed -----------------------------------
 
 1.  In some situations, fread() reread the first 1K or so of the file.