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]))
117 /*****************************************************************************/
119 /*****************************************************************************/
123 static int CompareFuncInfo (const void* Key, const void* Info)
124 /* Compare function for bsearch */
126 return strcmp (Key, ((const FuncInfo*) Info)->Name);
131 void GetFuncInfo (const char* Name, unsigned char* Use, unsigned char* Chg)
132 /* For the given function, lookup register information and store it into
133 * the given variables. If the function is unknown, assume it will use and
134 * load all registers.
137 /* If the function name starts with an underline, it is an external
138 * function. Search for it in the symbol table. If the function does
139 * not start with an underline, it may be a runtime support function.
140 * Search for it in the list of builtin functions.
142 if (Name[0] == '_') {
144 /* Search in the symbol table, skip the leading underscore */
145 SymEntry* E = FindSym (Name+1);
147 /* Did we find it in the top level table? */
148 if (E && E->Owner->PrevTab == 0 && IsTypeFunc (E->Type)) {
150 /* A function may use the A or A/X registers if it is a fastcall
151 * function. If it is not a fastcall function but a variadic one,
152 * it will use the Y register (the parameter size is passed here).
153 * In all other cases, no registers are used. However, we assume
154 * that any function will destroy all registers.
156 FuncDesc* D = E->V.F.Func;
157 if ((D->Flags & FD_FASTCALL) != 0 && D->ParamCount > 0) {
158 /* Will use registers depending on the last param */
159 SymEntry* LastParam = D->SymTab->SymTail;
160 if (SizeOf (LastParam->Type) == 1) {
165 } else if ((D->Flags & FD_VARIADIC) != 0) {
168 /* Will not use any registers */
172 /* Will destroy all registers */
181 /* Search for the function in the list of builtin functions */
182 const FuncInfo* Info = bsearch (Name, FuncInfoTable, FuncInfoCount,
183 sizeof(FuncInfo), CompareFuncInfo);
185 /* Do we know the function? */
187 /* Use the information we have */
194 /* Function not found - assume all registers used */
201 static unsigned char GetRegInfo2 (CodeSeg* S,
206 unsigned char Unused)
207 /* Recursively called subfunction for GetRegInfo. */
209 /* Follow the instruction flow recording register usage. */
214 /* Check if we have already visited the current code entry. If so,
217 if (CodeEntryHasMark (E)) {
221 /* Mark this entry as already visited */
222 CodeEntrySetMark (E);
223 CollAppend (Visited, E);
225 /* Evaluate the used registers */
227 if (E->OPC == OPC_RTS ||
228 ((E->Info & OF_BRA) != 0 && E->JumpTo == 0)) {
229 /* This instruction will leave the function */
233 /* We are not interested in the use of any register that has been
237 /* Remember the remaining registers */
241 /* Evaluate the changed registers */
242 if ((R = E->Chg) != REG_NONE) {
243 /* We are not interested in the use of any register that has been
247 /* Remember the remaining registers */
251 /* If we know about all registers now, bail out */
252 if ((Used | Unused) == REG_AXY) {
256 /* If the instruction is an RTS or RTI, we're done */
257 if (E->OPC == OPC_RTS || E->OPC == OPC_RTI) {
261 /* If we have an unconditional branch, follow this branch if possible,
262 * otherwise we're done.
264 if ((E->Info & OF_UBRA) != 0) {
266 /* Does this jump have a valid target? */
269 /* Unconditional jump */
270 E = E->JumpTo->Owner;
271 Index = -1; /* Invalidate */
274 /* Jump outside means we're done */
278 /* In case of conditional branches, follow the branch if possible and
279 * follow the normal flow (branch not taken) afterwards. If we cannot
280 * follow the branch, we're done.
282 } else if ((E->Info & OF_CBRA) != 0) {
286 /* Recursively determine register usage at the branch target */
290 U1 = GetRegInfo2 (S, E->JumpTo->Owner, -1, Visited, Used, Unused);
292 /* All registers used, no need for second call */
296 Index = GetCodeEntryIndex (S, E);
298 if ((E = GetCodeEntry (S, ++Index)) == 0) {
299 Internal ("GetRegInfo2: No next entry!");
301 U2 = GetRegInfo2 (S, E, Index, Visited, Used, Unused);
302 return U1 | U2; /* Used in any of the branches */
305 /* Jump to global symbol */
311 /* Just go to the next instruction */
313 Index = GetCodeEntryIndex (S, E);
315 E = GetCodeEntry (S, ++Index);
318 Internal ("GetRegInfo2: No next entry!");
325 /* Return to the caller the complement of all unused registers */
331 static unsigned char GetRegInfo1 (CodeSeg* S,
336 unsigned char Unused)
337 /* Recursively called subfunction for GetRegInfo. */
339 /* Remember the current count of the line collection */
340 unsigned Count = CollCount (Visited);
342 /* Call the worker routine */
343 unsigned char R = GetRegInfo2 (S, E, Index, Visited, Used, Unused);
345 /* Restore the old count, unmarking all new entries */
346 unsigned NewCount = CollCount (Visited);
347 while (NewCount-- > Count) {
348 CodeEntry* E = CollAt (Visited, NewCount);
349 CodeEntryResetMark (E);
350 CollDelete (Visited, NewCount);
353 /* Return the registers used */
359 unsigned char GetRegInfo (struct CodeSeg* S, unsigned Index)
360 /* Determine register usage information for the instructions starting at the
365 Collection Visited; /* Visited entries */
368 /* Get the code entry for the given index */
369 if (Index >= GetCodeEntryCount (S)) {
370 /* There is no such code entry */
373 E = GetCodeEntry (S, Index);
375 /* Initialize the data structure used to collection information */
376 InitCollection (&Visited);
378 /* Call the recursive subfunction */
379 R = GetRegInfo1 (S, E, Index, &Visited, REG_NONE, REG_NONE);
381 /* Delete the line collection */
382 DoneCollection (&Visited);
384 /* Return the registers used */
390 int RegAUsed (struct CodeSeg* S, unsigned Index)
391 /* Check if the value in A is used. */
393 return (GetRegInfo (S, Index) & REG_A) != 0;
398 int RegXUsed (struct CodeSeg* S, unsigned Index)
399 /* Check if the value in X is used. */
401 return (GetRegInfo (S, Index) & REG_X) != 0;
406 int RegYUsed (struct CodeSeg* S, unsigned Index)
407 /* Check if the value in Y is used. */
409 return (GetRegInfo (S, Index) & REG_Y) != 0;