Fixes for bug #144 (unitialized code paths in 6502 codegen).
authorShamus Hammons <jlhamm@acm.org>
Wed, 15 Jan 2020 04:14:01 +0000 (22:14 -0600)
committerShamus Hammons <jlhamm@acm.org>
Wed, 15 Jan 2020 04:14:01 +0000 (22:14 -0600)
I was able to throw away a bunch of code in m6502cg(); things should be
much clearer vis-a-vis how things are parsed and code flow through that
function.  Plus it's always nice to be able to throw away code.  :-)
Now at v2.0.9.

6502.c
version.h

diff --git a/6502.c b/6502.c
index 55eab740115446b4f1b3ad63437be70403bab82e..4397b0748bf446531317d3413908c4c6afb9bae5 100644 (file)
--- a/6502.c
+++ b/6502.c
@@ -249,18 +249,14 @@ int d_6502()
 void m6502cg(int op)
 {
        register int amode;             // (Parsed) addressing mode
-       register int i;
-       uint64_t eval;                  // Expression value
-       WORD eattr;                             // Expression attributes
-       int zpreq;                              // 1, optimize instr to zero-page form
-       register char * p;              // (Temp) string usage
+       uint64_t eval = -1;             // Expression value
+       WORD eattr = 0;                 // Expression attributes
+       int zpreq = 0;                  // 1 = optimize instr to zero-page form
        ch_size = 0;                    // Reset chunk size on every instruction
 
        //
        // Parse 6502 addressing mode
        //
-       zpreq = 0;
-
        switch (tok[0])
        {
        case EOL:
@@ -271,8 +267,8 @@ void m6502cg(int op)
                if (tok[1] != EOL)
                        goto badmode;
 
-               amode = A65_IMPL;
                tok++;
+               amode = A65_IMPL;
                break;
 
        case '#':
@@ -281,28 +277,19 @@ void m6502cg(int op)
                if (*tok == '>')
                {
                        tok++;
-
-                       if (expr(exprbuf, &eval, &eattr, NULL) < 0)
-                               return;
-
                        amode = A65_IMMEDH;
-                       break;
                }
                else if (*tok == '<')
                {
                        tok++;
-
-                       if (expr(exprbuf, &eval, &eattr, NULL) < 0)
-                               return;
-
                        amode = A65_IMMEDL;
-                       break;
                }
+               else
+                       amode = A65_IMMED;
 
                if (expr(exprbuf, &eval, &eattr, NULL) < 0)
                        return;
 
-               amode = A65_IMMED;
                break;
 
        case '(':
@@ -318,53 +305,21 @@ void m6502cg(int op)
                        {
                                // (foo),y
                                tok++;
-#if 0
-                               p = string[tok[1]];
-
-                               // Sleazo tolower() -----------------vvvvvvvvvvv
-                               if (*tok != SYMBOL || p[1] != EOS || (*p | 0x20) != 'y')
-                                       goto badmode;
-
-                               tok += 2;
                                amode = A65_INDY;
-#else
-                               if (tok[0] == KW_Y)
-                                       amode = A65_INDY;
 
-                               if (tok[1] != EOL)
+                               if (tok[0] != KW_Y)
                                        goto badmode;
 
                                tok++;
-#endif
                        }
                        else
                                amode = A65_IND;
                }
-               else if (*tok == ',')
+               else if ((tok[0] == ',') && (tok[1] == KW_X) && (tok[2] == ')'))
                {
                        // (foo,x)
-                       tok++;
-#if 0
-                       p = string[tok[1]];
-
-                       // Sleazo tolower() -----------------vvvvvvvvvvv
-                       if (*tok != SYMBOL || p[1] != EOS || (*p | 0x20) != 'x')
-                               goto badmode;
-
-                       tok += 2;
-                       if (*tok++ != ')')
-                               goto badmode;
-
+                       tok += 3;
                        amode = A65_INDX;
-#else
-                       if (tok[0] == KW_X)
-                               amode = A65_INDX;
-
-                       if ((tok[1] != ')') || (tok[2] != EOL))
-                               goto badmode;
-
-                       tok += 2;
-#endif
                }
                else
                        goto badmode;
@@ -382,23 +337,7 @@ void m6502cg(int op)
                if (*tok == '(')
                {
                        tok++;
-#if 0
-                       p = string[tok[1]];
-
-                       if (*tok != SYMBOL || p[1] != EOS || tok[2] != ')' || tok[3] != EOL)
-                               goto badmode;
-
-                       i = (*p | 0x20);        // Sleazo tolower()
-
-                       if (i == 'x')
-                               amode = A65_INDX;
-                       else if (i == 'y')
-                               amode = A65_INDY;
-                       else
-                               goto badmode;
 
-                       tok += 3;               // Past SYMBOL <string> ')' EOL
-#else
                        if ((tok[1] != ')') || (tok[2] != EOL))
                                goto badmode;
 
@@ -410,7 +349,6 @@ void m6502cg(int op)
                                goto badmode;
 
                        tok += 2;
-#endif
                        zpreq = 1;              // Request zeropage optimization
                }
                else if (*tok == EOL)
@@ -421,88 +359,30 @@ void m6502cg(int op)
                break;
 
        default:
-               //
-               // Short-circuit
-               //   x,foo
-               //   y,foo
-               //
-               p = string[tok[1]];
-               // ggn: the following code is effectively disabled as it would make
-               //      single letter labels not work correctly (would not identify the
-               //      label properly). And from what I understand it's something to
-               //      keep compatibility with the coinop assembler which is probably
-               //      something we don't care about much :D
-#if 0
-               if (*tok == SYMBOL && p[1] == EOS && tok[2] == ',')
-               {
-                       tok += 3;               // Past: SYMBOL <string> ','
-                       i = (*p | 0x20);
-
-                       if (i == 'x')
-                               amode = A65_ABSX;
-                       else if (i == 'y')
-                               amode = A65_ABSY;
-                       else
-                               goto not_coinop;
-
-                       if (expr(exprbuf, &eval, &eattr, NULL) < 0)
-                               return;
-
-                       if (*tok != EOL)
-                               goto badmode;
-
-                       zpreq = 1;
-                       break;
-               }
-
-not_coinop:
-#endif
+               //   <expr>
+               //   <expr>,x
+               //   <expr>,y
                if (expr(exprbuf, &eval, &eattr, NULL) < 0)
                        return;
 
-               zpreq = 1;
+               zpreq = 1;              // Request zeropage optimization
 
-               if (*tok == EOL)
+               if (tok[0] == EOL)
                        amode = A65_ABS;
-               else if (*tok == ',')
+               else if (tok[0] == ',')
                {
                        tok++;
-#if 0
-                       p = string[tok[1]];
-
-                       if (*tok != SYMBOL || p[1] != EOS)
-                               goto badmode;
-
-                       tok += 2;
 
-                       //
-                       // Check for X or Y index register;
-                       // the OR with 0x20 is a sleazo conversion
-                       // to lower-case that actually works.
-                       //
-                       i = *p | 0x20;  // Oooh, this is slimey (but fast!)
-
-                       if (i == 'x')
-                               amode = A65_ABSX;
-                       else if (i == 'y')
-                               amode = A65_ABSY;
-                       else
-                               goto badmode;
-#else
                        if (tok[0] == KW_X)
                        {
-                               amode = A65_ABSX;
                                tok++;
+                               amode = A65_ABSX;
                        }
                        else if (tok[0] == KW_Y)
                        {
-                               amode = A65_ABSY;
                                tok++;
+                               amode = A65_ABSY;
                        }
-
-                       if (tok[0] != EOL)
-                               goto badmode;
-#endif
                }
                else
                        goto badmode;
@@ -519,17 +399,17 @@ badmode:
        //   o  ZPX or ZPY is illegal, or
        //   o  expr is zeropage && zeropageRequest && expression is defined
        //
-       if (inf[op][amode] == ILLEGAL   // If current op is illegal,
-               || (eval < 0x100                        // or expr must be zero-page
-               && zpreq != 0                           // amode must request zero-page opt.
-               && (eattr & DEFINED)))          // and the expression must be defined
+       if ((inf[op][amode] == ILLEGAL) // If current op is illegal OR
+               || (zpreq                                       // amode requested a zero-page optimize
+                       && (eval < 0x100)               // and expr is zero-page
+                       && (eattr & DEFINED)))  // and the expression is defined
        {
-               i = abs2zp[amode];                      // i = zero-page translation of amode
+               int i = abs2zp[amode];          // Get zero-page translation of amode
 #ifdef DO_DEBUG
                DEBUG printf(" OPT: op=%d amode=%d i=%d inf[op][i]=%d\n",
                                         op, amode, i, inf[op][i]);
 #endif
-               if (i >= 0 && (inf[op][i] & 0xFF) != ILLEGAL) // Use it if it's legal
+               if (i >= 0 && (inf[op][i] & 0xFF) != ILLEGAL) // & use it if it's legal
                        amode = i;
        }
 
@@ -635,8 +515,9 @@ badmode:
                //
                default:
                case ILLEGAL:
-                       for(i=0; i<3; i++)
-                               D_byte(NOP);
+                       D_byte(NOP);
+                       D_byte(NOP);
+                       D_byte(NOP);
 
                        error("illegal 6502 addressing mode");
        }
index bb575e42c6b9c05325be2f4058fc6f3c1a59c0fb..b616e51f20ff986e8ae60ca24a609de3154ca8cf 100644 (file)
--- a/version.h
+++ b/version.h
@@ -15,7 +15,7 @@
 
 #define MAJOR   2              // Major version number
 #define MINOR   0              // Minor version number
-#define PATCH   8              // Patch release number
+#define PATCH   9              // Patch release number
 
 #endif // __VERSION_H__