1 /*****************************************************************************/
5 /* Parse function entry/body/exit */
9 /* (C) 2000 Ullrich von Bassewitz */
11 /* D-70597 Stuttgart */
12 /* EMail: uz@musoftware.de */
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 /*****************************************************************************/
56 /*****************************************************************************/
58 /*****************************************************************************/
62 /* Structure that holds all data needed for function activation */
64 struct SymEntry* FuncEntry; /* Symbol table entry */
65 type* ReturnType; /* Function return type */
66 struct FuncDesc* Desc; /* Function descriptor */
67 CodeMark EntryCode; /* Backpatch addr for entry code */
68 int Reserved; /* Reserved local space */
69 unsigned RetLab; /* Return code label */
72 /* Pointer to current function */
73 Function* CurrentFunc = 0;
77 /*****************************************************************************/
78 /* Subroutines working with struct Function */
79 /*****************************************************************************/
83 static Function* NewFunction (struct SymEntry* Sym)
84 /* Create a new function activation structure and return it */
86 /* Allocate a new structure */
87 Function* F = (Function*) xmalloc (sizeof (Function));
89 /* Initialize the fields */
91 F->ReturnType = Sym->Type + 1 + DECODE_SIZE;
92 F->Desc = (FuncDesc*) DecodePtr (Sym->Type + 1);
95 F->RetLab = GetLabel ();
97 /* Return the new structure */
103 static void FreeFunction (Function* F)
104 /* Free a function activation structure */
111 const char* GetFuncName (const Function* F)
112 /* Return the name of the current function */
114 return F->FuncEntry->Name;
119 unsigned GetParamCount (const Function* F)
120 /* Return the parameter count for the current function */
122 return F->Desc->ParamCount;
127 unsigned GetParamSize (const Function* F)
128 /* Return the parameter size for the current function */
130 return F->Desc->ParamSize;
135 type* GetReturnType (Function* F)
136 /* Get the return type for the function */
138 return F->ReturnType;
143 int HasVoidReturn (const Function* F)
144 /* Return true if the function does not have a return value */
146 return IsTypeVoid (F->ReturnType);
151 int IsVariadic (const Function* F)
152 /* Return true if this is a variadic function */
154 return (F->Desc->Flags & FD_ELLIPSIS) != 0;
159 void RememberEntry (Function* F)
160 /* Remember the current output position for local space creation later */
162 F->EntryCode = GetCodePos ();
167 unsigned GetRetLab (const Function* F)
168 /* Return the return jump label */
175 int ReserveLocalSpace (Function* F, unsigned Size)
176 /* Reserve (but don't allocate) the given local space and return the stack
181 return oursp - F->Reserved;
186 void AllocLocalSpace (Function* F)
187 /* Allocate any local space previously reserved. The function will do
188 * nothing if there is no reserved local space.
191 if (F->Reserved > 0) {
193 /* Switch to the code segment */
196 /* Create space on the stack */
197 g_space (F->Reserved);
199 /* Correct the stack pointer */
200 oursp -= F->Reserved;
202 /* Nothing more reserved */
209 /*****************************************************************************/
211 /*****************************************************************************/
215 void NewFunc (SymEntry* Func)
216 /* Parse argument declarations and function body. */
221 /* Get the function descriptor from the function entry */
222 FuncDesc* D = (FuncDesc*) DecodePtr (Func->Type+1);
224 /* Allocate the function activation record for the function */
225 CurrentFunc = NewFunction (Func);
227 /* Reenter the lexical level */
228 ReenterFunctionLevel (D);
230 /* Declare two special functions symbols: __fixargs__ and __argsize__.
231 * The latter is different depending on the type of the function (variadic
234 AddConstSym ("__fixargs__", type_uint, SC_DEF | SC_CONST, D->ParamSize);
235 if (D->Flags & FD_ELLIPSIS) {
236 /* Variadic function. The variable must be const. */
237 static const type T [] = { T_UCHAR | T_QUAL_CONST, T_END };
238 AddLocalSym ("__argsize__", T, SC_DEF | SC_REF | SC_AUTO, 0);
241 AddConstSym ("__argsize__", type_uchar, SC_DEF | SC_CONST, D->ParamSize);
244 /* Function body now defined */
245 Func->Flags |= SC_DEF;
247 /* Need a starting curly brace */
248 if (curtok != TOK_LCURLY) {
249 Error ("`{' expected");
252 /* Setup register variables */
255 /* Switch to the code segment and define the function name label */
257 g_defgloblabel (Func->Name);
259 /* If this is a fastcall function, push the last parameter onto the stack */
260 if (IsFastCallFunc (Func->Type) && D->ParamCount > 0) {
265 /* Fastcall functions may never have an ellipsis or the compiler is buggy */
266 CHECK ((D->Flags & FD_ELLIPSIS) == 0);
268 /* Get a pointer to the last parameter entry */
269 LastParam = D->SymTab->SymTail;
271 /* Generate the push */
272 if (IsTypeFunc (LastParam->Type)) {
273 /* Pointer to function */
276 Flags = TypeOf (LastParam->Type) | CF_FORCECHAR;
281 /* If stack checking code is requested, emit a call to the helper routine */
286 /* Generate function entry code if needed */
287 g_enter (TypeOf (Func->Type), GetParamSize (CurrentFunc));
289 /* Remember the current code position. This may be used later to create
290 * local variable space once we have created the function body itself.
291 * Currently this is not possible because the stack offsets of all locals
292 * have to be known in advance.
294 RememberEntry (CurrentFunc);
296 /* Parse the function body */
300 /* If the function did not end with an return statement, create exit code */
303 /* If the function has a return type, flag an error */
305 Error ("Function `%s' must return a value", Func->Name);
310 Flags = HasVoidReturn (CurrentFunc)? CF_NONE : CF_REG;
314 /* Dump literal data created by the function */
317 /* Cleanup register variables */
320 /* Leave the lexical level */
321 LeaveFunctionLevel ();
323 /* Reset the current function pointer */
324 FreeFunction (CurrentFunc);