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Revise variable argument handling to better comply with standards.

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In the new implementation, variable arguments are not removed until the end of the function. This allows variable argument processing to be restarted, and it prevents the addresses of local variables from changing in the middle of the function. The requirement to turn off stack repair code around varargs functions is also removed.

This fixes #58.
This commit is contained in:
Stephen Heumann 2021-10-23 21:18:09 -05:00
parent 6e32bfc091
commit a20d69a211
4 changed files with 84 additions and 10 deletions
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13
ORCACDefs/stdarg.h
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@ -14,6 +14,11 @@
*
* Thanks to Doug Gwyn for the new va_start & va_arg declarations.
*
*****************************************************************
*
* Modified October 2021 for better standards conformance.
* This version will only work with ORCA/C 2.2.0 B6 or later.
*
****************************************************************/
#ifndef __stdarg__
@ -25,12 +30,12 @@ typedef char *__va_list[2];
#endif
typedef __va_list va_list;
#define va_end(a) __va_end(a)
#define va_start(ap,LastFixedParm) ((void) ((ap)[0] = (ap)[1] = (char *) (&LastFixedParm + 1)))
#define va_arg(ap,type) _Generic(*(type *)0, \
#define va_end(ap) __record_va_info(ap)
#define va_start(ap,LastFixedParm) ((void) ((ap)[0] = (char *) (&LastFixedParm + 1), (ap)[1] = (char *)&__orcac_va_info))
#define va_arg(ap,type) _Generic(*(type *)0, \
double: (type)((long double *)((ap)[0] += sizeof(long double)))[-1], \
default: ((type *)((ap)[0] += sizeof(type)))[-1])
void __va_end(va_list);
void __record_va_info(va_list);
#endif

18
Parser.pas
View File

@ -186,6 +186,7 @@ var
doingForLoopClause1: boolean; {doing the first clause of a for loop?}
compoundLiteralNumber: integer; {number of compound literal}
compoundLiteralToAllocate: identPtr; {compound literal that needs space allocated}
vaInfoLLN: integer; {label number of internal va info (0 for none)}
{parameter processing variables}
{------------------------------}
@ -362,6 +363,11 @@ if not doingFunction then begin {if so, finish it off}
end; {else if}
end; {if}
Gen1(dc_lab, returnLabel);
if vaInfoLLN <> 0 then begin {clean up variable args, if any}
Gen2(pc_lda, vaInfoLLN, 0);
Gen0t(pc_stk, cgULong);
Gen1tName(pc_cup, -1, cgVoid, @'__va_end');
end; {if}
with fType^ do {generate the pc_ret instruction}
case kind of
scalarType : Gen0t(pc_ret, baseType);
@ -3884,6 +3890,18 @@ if isFunction then begin
GenParameters(fnType^.parameterList);
savedVolatile := volatile;
functionTable := table;
if fnType^.varargs then begin {make internal va info for varargs funcs}
lp := NewSymbol(@'__orcac_va_info', vaInfoPtr, autosy,
variableSpace, declared);
lp^.lln := GetLocalLabel;
Gen2(dc_loc, lp^.lln, ord(vaInfoPtr^.size));
Gen2(pc_lda, lastParameterLLN, lastParameterSize);
Gen2t(pc_cop, lp^.lln, 0, cgULong);
Gen2t(pc_str, lp^.lln, cgPointerSize, cgULong);
vaInfoLLN := lp^.lln;
end {if}
else
vaInfoLLN := 0;
CompoundStatement(false); {process the statements}
end; {else}
end; {else}

53
Symbol.pas
View File

@ -45,6 +45,8 @@
{ boolPtr - pointer to the base type for _Bool }
{ voidPtr - pointer to the base type for void }
{ voidPtrPtr - typeless pointer, for some type casting }
{ charPtrPtr - pointer to type record for char * }
{ vaInfoPtr - pointer to type record for internal va info type }
{ stringTypePtr - pointer to the base type for string literals }
{ utf16StringTypePtr - pointer to the base type for UTF-16 }
{ string literals }
@ -82,11 +84,16 @@ var
globalTable: symbolTablePtr; {global symbol table}
functionTable: symbolTablePtr; {table for top level of current function}
{output from GenParameters}
lastParameterLLN: integer; {label number of last parameter (0 if none)}
lastParameterSize: integer; {size of last parameter}
{base types}
charPtr,sCharPtr,uCharPtr,shortPtr,uShortPtr,intPtr,uIntPtr,int32Ptr,
uInt32Ptr,longPtr,uLongPtr,longLongPtr,uLongLongPtr,boolPtr,
floatPtr,doublePtr,compPtr,extendedPtr,stringTypePtr,utf16StringTypePtr,
utf32StringTypePtr,voidPtr,voidPtrPtr,constCharPtr,defaultStruct: typePtr;
utf32StringTypePtr,voidPtr,voidPtrPtr,charPtrPtr,vaInfoPtr,constCharPtr,
defaultStruct: typePtr;
{---------------------------------------------------------------}
@ -134,6 +141,10 @@ procedure GenParameters (pp: parameterPtr);
{ }
{ parameters: }
{ pp - pointer to first parameter }
{ }
{ variables: }
{ lastParameterLLN - label number of last parameter }
{ lastParameterSize - size of last parameter }
procedure GenSymbols (sym: symbolTablePtr; doGlobals: boolean);
@ -945,6 +956,10 @@ procedure GenParameters {pp: parameterPtr};
{ }
{ parameters: }
{ pp - pointer to first parameter }
{ }
{ variables: }
{ lastParameterLLN - label number of last parameter }
{ lastParameterSize - size of last parameter }
var
i: 0..hashSize; {loop variable}
@ -954,6 +969,8 @@ var
tk: tokenType; {symbol name token}
begin {GenParameters}
pln := 0;
size := 0;
if pp <> nil then begin {prototyped parameters}
tk.kind := ident;
tk.numString := nil;
@ -965,8 +982,10 @@ if pp <> nil then begin {prototyped parameters}
sp := FindSymbol(tk, variableSpace, true, false);
if sp = nil then
sp := pp^.parameter;
if sp^.itype^.kind = arrayType then
Gen3(dc_prm, pln, cgPointerSize, sp^.pdisp)
if sp^.itype^.kind = arrayType then begin
size := cgPointerSize;
Gen3(dc_prm, pln, cgPointerSize, sp^.pdisp);
end {if}
else begin
size := long(sp^.itype^.size).lsw;
if (size = 1) and (sp^.itype^.kind = scalarType) then
@ -982,9 +1001,12 @@ else begin {K&R parameters}
sp := table^.buckets[i];
while sp <> nil do begin
if sp^.storage = parameter then begin
sp^.pln := GetLocalLabel;
if sp^.itype^.kind = arrayType then
Gen3(dc_prm, sp^.lln, cgPointerSize, sp^.pdisp)
pln := GetLocalLabel;
sp^.pln := pln;
if sp^.itype^.kind = arrayType then begin
size := cgPointerSize;
Gen3(dc_prm, sp^.lln, cgPointerSize, sp^.pdisp);
end {if}
else begin
size := long(sp^.itype^.size).lsw;
if (size = 1) and (sp^.itype^.kind = scalarType) then
@ -996,6 +1018,8 @@ else begin {K&R parameters}
end; {while}
end; {for}
end; {else}
lastParameterLLN := pln;
lastParameterSize := size;
end; {GenParameters}
@ -1605,6 +1629,23 @@ with voidPtrPtr^ do begin
kind := pointerType;
pType := voidPtr;
end; {with}
new(charPtrPtr); {char *}
with charPtrPtr^ do begin
size := cgPointerSize;
saveDisp := 0;
qualifiers := [];
kind := pointerType;
pType := charPtr;
end; {with}
new(vaInfoPtr); {internal varargs info type (char*[2])}
with vaInfoPtr^ do begin
size := cgPointerSize*2;
saveDisp := 0;
qualifiers := [];
kind := arrayType;
aType := charPtrPtr;
elements := 2;
end; {with}
new(defaultStruct); {default structure}
with defaultStruct^ do begin {(for structures with errors)}
size := cgWordSize;

10
cc.notes
View File

@ -216,6 +216,10 @@ Unions can be initialized by a brace-enclosed expression giving the initializer
union nums {float f; int i;} x = {0.0};
p. 297
Variable argument lists will now work even if stack repair code is enabled.
p. 311
If integer overflow occurs during signed integer multiplication, the resulting value is not predictable. Contrary to what the description in the manual implies, it will not necessarily be the low-order bits from the true product of the operands.
@ -304,6 +308,10 @@ p. 405
The discussion of _toupper should note that _toupper is an extension to ANSI C.
p. 406
va_end is now a macro, not a function. Also, the va_arg, va_end, and va_start macros will now work even if stack repair code is enabled.
p. 444,445
The control codes to turn the cursor on and off are no longer used in the .CONSOLE driver, which is what the current version of ORCA/C uses for all text output. In the .CONSOLE driver, the cursor is always off unless it is waiting for a character.
@ -1378,6 +1386,8 @@ int foo(int[42]);
169. If an assembly-language function (declared with the asm keyword) had a structure or union return type, ORCA/C would generate some spurious code at the beginning of the function, which might trash data used by its caller.
170. Variable argument processing could not be restarted by calling va_start() after va_end(). Also, the addresses of local variables would change when va_end() was called, invalidating any pointers to them. The implementation of variable arguments has been changed to fix these problems. The only remaining non-standard restriction is that if #pragma optimize bit 6 or #pragma debug bit 4 is set, calls to functions taking variable arguments are not allowed to pass extra arguments beyond the number that the function will use.
-- Bugs from C 2.1.0 that have been fixed -----------------------------------
1. In some situations, fread() reread the first 1K or so of the file.