1 /*****************************************************************************/
5 /* Additional information about 6502 code */
9 /* (C) 2001 Ullrich von Bassewitz */
11 /* D-70597 Stuttgart */
12 /* EMail: uz@cc65.org */
15 /* This software is provided 'as-is', without any expressed or implied */
16 /* warranty. In no event will the authors be held liable for any damages */
17 /* arising from the use of this software. */
19 /* Permission is granted to anyone to use this software for any purpose, */
20 /* including commercial applications, and to alter it and redistribute it */
21 /* freely, subject to the following restrictions: */
23 /* 1. The origin of this software must not be misrepresented; you must not */
24 /* claim that you wrote the original software. If you use this software */
25 /* in a product, an acknowledgment in the product documentation would be */
26 /* appreciated but is not required. */
27 /* 2. Altered source versions must be plainly marked as such, and must not */
28 /* be misrepresented as being the original software. */
29 /* 3. This notice may not be removed or altered from any source */
32 /*****************************************************************************/
52 /*****************************************************************************/
54 /*****************************************************************************/
58 /* Table listing the function names and code info values for known internally
59 * used functions. This table should get auto-generated in the future.
61 typedef struct FuncInfo FuncInfo;
63 const char* Name; /* Function name */
64 unsigned char Use; /* Register usage */
65 unsigned char Chg; /* Changed/destroyed registers */
68 static const FuncInfo FuncInfoTable[] = {
69 { "addysp", REG_Y, REG_NONE },
70 { "booleq", REG_NONE, REG_AX },
71 { "boolge", REG_NONE, REG_AX },
72 { "boolgt", REG_NONE, REG_AX },
73 { "boolle", REG_NONE, REG_AX },
74 { "boollt", REG_NONE, REG_AX },
75 { "boolne", REG_NONE, REG_AX },
76 { "booluge", REG_NONE, REG_AX },
77 { "boolugt", REG_NONE, REG_AX },
78 { "boolule", REG_NONE, REG_AX },
79 { "boolult", REG_NONE, REG_AX },
80 { "decax1", REG_AX, REG_AX },
81 { "decax2", REG_AX, REG_AX },
82 { "decax3", REG_AX, REG_AX },
83 { "decax4", REG_AX, REG_AX },
84 { "decax5", REG_AX, REG_AX },
85 { "decax6", REG_AX, REG_AX },
86 { "decax7", REG_AX, REG_AX },
87 { "decax8", REG_AX, REG_AX },
88 { "decaxy", REG_AXY, REG_AX },
89 { "decsp2", REG_NONE, REG_A },
90 { "decsp3", REG_NONE, REG_A },
91 { "decsp4", REG_NONE, REG_A },
92 { "decsp5", REG_NONE, REG_A },
93 { "decsp6", REG_NONE, REG_A },
94 { "decsp7", REG_NONE, REG_A },
95 { "decsp8", REG_NONE, REG_A },
96 { "incsp1", REG_NONE, REG_NONE },
97 { "incsp2", REG_NONE, REG_Y },
98 { "incsp3", REG_NONE, REG_Y },
99 { "incsp4", REG_NONE, REG_Y },
100 { "incsp5", REG_NONE, REG_Y },
101 { "incsp6", REG_NONE, REG_Y },
102 { "incsp7", REG_NONE, REG_Y },
103 { "incsp8", REG_NONE, REG_Y },
104 { "ldax0sp", REG_Y, REG_AX },
105 { "ldaxysp", REG_Y, REG_AX },
106 { "pusha", REG_A, REG_Y },
107 { "pusha0", REG_A, REG_XY },
108 { "pushax", REG_AX, REG_Y },
109 { "pushw0sp", REG_NONE, REG_AXY },
110 { "pushwysp", REG_Y, REG_AXY },
111 { "tosicmp", REG_AX, REG_AXY },
113 #define FuncInfoCount (sizeof(FuncInfoTable) / sizeof(FuncInfoTable[0]))
115 /* Table with names of zero page locations used by the compiler */
116 static const char* ZPNameTable[] = {
117 "ptr1", "regbank", "regsave", "sp", "sreg", "tmp1"
119 #define ZPNameCount (sizeof(ZPNameTable) / sizeof(ZPNameTable[0]))
122 /*****************************************************************************/
124 /*****************************************************************************/
128 static int CompareFuncInfo (const void* Key, const void* Info)
129 /* Compare function for bsearch */
131 return strcmp (Key, ((const FuncInfo*) Info)->Name);
136 void GetFuncInfo (const char* Name, unsigned char* Use, unsigned char* Chg)
137 /* For the given function, lookup register information and store it into
138 * the given variables. If the function is unknown, assume it will use and
139 * load all registers.
142 /* If the function name starts with an underline, it is an external
143 * function. Search for it in the symbol table. If the function does
144 * not start with an underline, it may be a runtime support function.
145 * Search for it in the list of builtin functions.
147 if (Name[0] == '_') {
149 /* Search in the symbol table, skip the leading underscore */
150 SymEntry* E = FindSym (Name+1);
152 /* Did we find it in the top level table? */
153 if (E && E->Owner->PrevTab == 0 && IsTypeFunc (E->Type)) {
155 /* A function may use the A or A/X registers if it is a fastcall
156 * function. If it is not a fastcall function but a variadic one,
157 * it will use the Y register (the parameter size is passed here).
158 * In all other cases, no registers are used. However, we assume
159 * that any function will destroy all registers.
161 FuncDesc* D = E->V.F.Func;
162 if ((D->Flags & FD_FASTCALL) != 0 && D->ParamCount > 0) {
163 /* Will use registers depending on the last param */
164 SymEntry* LastParam = D->SymTab->SymTail;
165 if (SizeOf (LastParam->Type) == 1) {
170 } else if ((D->Flags & FD_VARIADIC) != 0) {
173 /* Will not use any registers */
177 /* Will destroy all registers */
186 /* Search for the function in the list of builtin functions */
187 const FuncInfo* Info = bsearch (Name, FuncInfoTable, FuncInfoCount,
188 sizeof(FuncInfo), CompareFuncInfo);
190 /* Do we know the function? */
192 /* Use the information we have */
199 /* Function not found - assume all registers used */
206 int IsZPName (const char* Name)
207 /* Return true if the given name is a zero page symbol */
211 /* Because of the low number of symbols, we do a linear search here */
212 for (I = 0; I < ZPNameCount; ++I) {
213 if (strcmp (Name, ZPNameTable[I]) == 0) {
225 static unsigned char GetRegInfo2 (CodeSeg* S,
230 unsigned char Unused)
231 /* Recursively called subfunction for GetRegInfo. */
233 /* Follow the instruction flow recording register usage. */
238 /* Check if we have already visited the current code entry. If so,
241 if (CodeEntryHasMark (E)) {
245 /* Mark this entry as already visited */
246 CodeEntrySetMark (E);
247 CollAppend (Visited, E);
249 /* Evaluate the used registers */
251 if (E->OPC == OPC_RTS ||
252 ((E->Info & OF_BRA) != 0 && E->JumpTo == 0)) {
253 /* This instruction will leave the function */
257 /* We are not interested in the use of any register that has been
261 /* Remember the remaining registers */
265 /* Evaluate the changed registers */
266 if ((R = E->Chg) != REG_NONE) {
267 /* We are not interested in the use of any register that has been
271 /* Remember the remaining registers */
275 /* If we know about all registers now, bail out */
276 if ((Used | Unused) == REG_AXY) {
280 /* If the instruction is an RTS or RTI, we're done */
281 if (E->OPC == OPC_RTS || E->OPC == OPC_RTI) {
285 /* If we have an unconditional branch, follow this branch if possible,
286 * otherwise we're done.
288 if ((E->Info & OF_UBRA) != 0) {
290 /* Does this jump have a valid target? */
293 /* Unconditional jump */
294 E = E->JumpTo->Owner;
295 Index = -1; /* Invalidate */
298 /* Jump outside means we're done */
302 /* In case of conditional branches, follow the branch if possible and
303 * follow the normal flow (branch not taken) afterwards. If we cannot
304 * follow the branch, we're done.
306 } else if ((E->Info & OF_CBRA) != 0) {
310 /* Recursively determine register usage at the branch target */
314 U1 = GetRegInfo2 (S, E->JumpTo->Owner, -1, Visited, Used, Unused);
316 /* All registers used, no need for second call */
320 Index = GetCodeEntryIndex (S, E);
322 if ((E = GetCodeEntry (S, ++Index)) == 0) {
323 Internal ("GetRegInfo2: No next entry!");
325 U2 = GetRegInfo2 (S, E, Index, Visited, Used, Unused);
326 return U1 | U2; /* Used in any of the branches */
329 /* Jump to global symbol */
335 /* Just go to the next instruction */
337 Index = GetCodeEntryIndex (S, E);
339 E = GetCodeEntry (S, ++Index);
342 Internal ("GetRegInfo2: No next entry!");
349 /* Return to the caller the complement of all unused registers */
355 static unsigned char GetRegInfo1 (CodeSeg* S,
360 unsigned char Unused)
361 /* Recursively called subfunction for GetRegInfo. */
363 /* Remember the current count of the line collection */
364 unsigned Count = CollCount (Visited);
366 /* Call the worker routine */
367 unsigned char R = GetRegInfo2 (S, E, Index, Visited, Used, Unused);
369 /* Restore the old count, unmarking all new entries */
370 unsigned NewCount = CollCount (Visited);
371 while (NewCount-- > Count) {
372 CodeEntry* E = CollAt (Visited, NewCount);
373 CodeEntryResetMark (E);
374 CollDelete (Visited, NewCount);
377 /* Return the registers used */
383 unsigned char GetRegInfo (struct CodeSeg* S, unsigned Index)
384 /* Determine register usage information for the instructions starting at the
389 Collection Visited; /* Visited entries */
392 /* Get the code entry for the given index */
393 if (Index >= GetCodeEntryCount (S)) {
394 /* There is no such code entry */
397 E = GetCodeEntry (S, Index);
399 /* Initialize the data structure used to collection information */
400 InitCollection (&Visited);
402 /* Call the recursive subfunction */
403 R = GetRegInfo1 (S, E, Index, &Visited, REG_NONE, REG_NONE);
405 /* Delete the line collection */
406 DoneCollection (&Visited);
408 /* Return the registers used */
414 int RegAUsed (struct CodeSeg* S, unsigned Index)
415 /* Check if the value in A is used. */
417 return (GetRegInfo (S, Index) & REG_A) != 0;
422 int RegXUsed (struct CodeSeg* S, unsigned Index)
423 /* Check if the value in X is used. */
425 return (GetRegInfo (S, Index) & REG_X) != 0;
430 int RegYUsed (struct CodeSeg* S, unsigned Index)
431 /* Check if the value in Y is used. */
433 return (GetRegInfo (S, Index) & REG_Y) != 0;