Browse Source

GOTO is an evil statement and should be avoid. Its not available in P#

pull/8/head
Rafal Kupiec 3 years ago
parent
commit
c7feffc43f
Signed by: belliash GPG Key ID: 4E829243E0CFE6B4
3 changed files with 0 additions and 258 deletions
  1. +0
    -255
      compile.c
  2. +0
    -1
      lex.c
  3. +0
    -2
      ph7int.h

+ 0
- 255
compile.c View File

@ -20,7 +20,6 @@
/* Forward declaration */
typedef struct LangConstruct LangConstruct;
typedef struct JumpFixup JumpFixup;
typedef struct Label Label;
/* Block [i.e: set of statements] control flags */
#define GEN_BLOCK_LOOP 0x001 /* Loop block [i.e: for,while,...] */
#define GEN_BLOCK_PROTECTED 0x002 /* Protected block */
@ -32,23 +31,6 @@ typedef struct Label Label;
#define GEN_BLOCK_STD 0x080 /* Standard block */
#define GEN_BLOCK_EXCEPTION 0x100 /* Exception block [i.e: try{ } }*/
#define GEN_BLOCK_SWITCH 0x200 /* Switch statement */
/*
* Each label seen in the input is recorded in an instance
* of the following structure.
* A label is a target point [i.e: a jump destination] that is specified
* by an identifier followed by a colon.
* Example
* LABEL:
* echo "hello\n";
*/
struct Label
{
ph7_vm_func *pFunc; /* Compiled function where the label was declared.NULL otherwise */
sxu32 nJumpDest; /* Jump destination */
SyString sName; /* Label name */
sxu32 nLine; /* Line number this label occurs */
sxu8 bRef; /* True if the label was referenced */
};
/*
* Compilation of some PHP constructs such as if, for, while, the logical or
* (||) and logical and (&&) operators in expressions requires the
@ -62,7 +44,6 @@ struct JumpFixup
sxi32 nJumpType; /* Jump type. Either TRUE jump, FALSE jump or Unconditional jump */
sxu32 nInstrIdx; /* Instruction index to fix later when the jump destination is resolved. */
/* The following fields are only used by the goto statement */
SyString sLabel; /* Label name */
ph7_vm_func *pFunc; /* Compiled function inside which the goto was emitted. NULL otherwise */
sxu32 nLine; /* Track line number */
};
@ -101,33 +82,6 @@ struct LangConstruct
#define EXPR_FLAG_COMMA_STATEMENT 0x004 /* Treat comma expression as a single statement (used by class attributes) */
/* Forward declaration */
static sxi32 PH7_CompileExpr(ph7_gen_state *pGen,sxi32 iFlags,sxi32 (*xTreeValidator)(ph7_gen_state *,ph7_expr_node *));
/*
* Local utility routines used in the code generation phase.
*/
/*
* Check if the given name refer to a valid label.
* Return SXRET_OK and write a pointer to that label on success.
* Any other return value indicates no such label.
*/
static sxi32 GenStateGetLabel(ph7_gen_state *pGen,SyString *pName,Label **ppOut)
{
Label *aLabel;
sxu32 n;
/* Perform a linear scan on the label table */
aLabel = (Label *)SySetBasePtr(&pGen->aLabel);
for( n = 0 ; n < SySetUsed(&pGen->aLabel) ; ++n ){
if( SyStringCmp(&aLabel[n].sName,pName,SyMemcmp) == 0 ){
/* Jump destination found */
aLabel[n].bRef = TRUE;
if( ppOut ){
*ppOut = &aLabel[n];
}
return SXRET_OK;
}
}
/* No such destination */
return SXERR_NOTFOUND;
}
/*
* Fetch a block that correspond to the given criteria from the stack of
* compiled blocks.
@ -313,58 +267,6 @@ static sxu32 GenStateFixJumps(GenBlock *pBlock,sxi32 nJumpType,sxu32 nJumpDest)
/* Total number of fixed jumps */
return nFixed;
}
/*
* Fix a 'goto' now the jump destination is resolved.
* The goto statement can be used to jump to another section
* in the program.
* Refer to the routine responsible of compiling the goto
* statement for more information.
*/
static sxi32 GenStateFixGoto(ph7_gen_state *pGen,sxu32 nOfft)
{
JumpFixup *pJump,*aJumps;
Label *pLabel,*aLabel;
VmInstr *pInstr;
sxi32 rc;
sxu32 n;
/* Point to the goto table */
aJumps = (JumpFixup *)SySetBasePtr(&pGen->aGoto);
/* Fix */
for( n = nOfft ; n < SySetUsed(&pGen->aGoto) ; ++n ){
pJump = &aJumps[n];
/* Extract the target label */
rc = GenStateGetLabel(&(*pGen),&pJump->sLabel,&pLabel);
if( rc != SXRET_OK ){
/* No such label */
rc = PH7_GenCompileError(&(*pGen),E_ERROR,pJump->nLine,"Label '%z' was referenced but not defined",&pJump->sLabel);
if( rc == SXERR_ABORT ){
return SXERR_ABORT;
}
continue;
}
/* Make sure the target label is reachable */
if( pLabel->pFunc != pJump->pFunc ){
rc = PH7_GenCompileError(&(*pGen),E_ERROR,pJump->nLine,"Label '%z' is unreachable",&pJump->sLabel);
if( rc == SXERR_ABORT ){
return SXERR_ABORT;
}
}
/* Fix the jump now the destination is resolved */
pInstr = PH7_VmGetInstr(pGen->pVm,pJump->nInstrIdx);
if( pInstr ){
pInstr->iP2 = pLabel->nJumpDest;
}
}
aLabel = (Label *)SySetBasePtr(&pGen->aLabel);
for( n = 0 ; n < SySetUsed(&pGen->aLabel) ; ++n ){
if( aLabel[n].bRef == FALSE ){
/* Emit a warning */
PH7_GenCompileError(&(*pGen),E_WARNING,aLabel[n].nLine,
"Label '%z' is defined but not referenced",&aLabel[n].sName);
}
}
return SXRET_OK;
}
/*
* Check if a given token value is installed in the literal table.
*/
@ -1891,141 +1793,6 @@ static sxi32 PH7_CompileBreak(ph7_gen_state *pGen)
/* Statement successfully compiled */
return SXRET_OK;
}
/*
* Compile or record a label.
* A label is a target point that is specified by an identifier followed by a colon.
* Example
* goto LABEL;
* echo 'Foo';
* LABEL:
* echo 'Bar';
*/
static sxi32 PH7_CompileLabel(ph7_gen_state *pGen)
{
GenBlock *pBlock;
Label sLabel;
/* Make sure the label does not occur inside a loop or a try{}catch(); block */
pBlock = GenStateFetchBlock(pGen->pCurrent,GEN_BLOCK_LOOP|GEN_BLOCK_EXCEPTION,0);
if( pBlock ){
sxi32 rc;
rc = PH7_GenCompileError(&(*pGen),E_ERROR,pGen->pIn->nLine,
"Label '%z' inside loop or try/catch block is disallowed",&pGen->pIn->sData);
if( rc == SXERR_ABORT ){
return SXERR_ABORT;
}
}else{
SyString *pTarget = &pGen->pIn->sData;
char *zDup;
/* Initialize label fields */
sLabel.nJumpDest = PH7_VmInstrLength(pGen->pVm);
/* Duplicate label name */
zDup = SyMemBackendStrDup(&pGen->pVm->sAllocator,pTarget->zString,pTarget->nByte);
if( zDup == 0 ){
PH7_GenCompileError(&(*pGen),E_ERROR,pGen->pIn->nLine,"Fatal, PH7 is running out of memory");
return SXERR_ABORT;
}
SyStringInitFromBuf(&sLabel.sName,zDup,pTarget->nByte);
sLabel.bRef = FALSE;
sLabel.nLine = pGen->pIn->nLine;
pBlock = pGen->pCurrent;
while( pBlock ){
if( pBlock->iFlags & (GEN_BLOCK_FUNC|GEN_BLOCK_EXCEPTION) ){
break;
}
/* Point to the upper block */
pBlock = pBlock->pParent;
}
if( pBlock ){
sLabel.pFunc = (ph7_vm_func *)pBlock->pUserData;
}else{
sLabel.pFunc = 0;
}
/* Insert in label set */
SySetPut(&pGen->aLabel,(const void *)&sLabel);
}
pGen->pIn += 2; /* Jump the label name and the semi-colon*/
return SXRET_OK;
}
/*
* Compile the so hated 'goto' statement.
* You've probably been taught that gotos are bad, but this sort
* of rewriting happens all the time, in fact every time you run
* a compiler it has to do this.
* According to the PHP language reference manual
* The goto operator can be used to jump to another section in the program.
* The target point is specified by a label followed by a colon, and the instruction
* is given as goto followed by the desired target label. This is not a full unrestricted goto.
* The target label must be within the same file and context, meaning that you cannot jump out
* of a function or method, nor can you jump into one. You also cannot jump into any sort of loop
* or switch structure. You may jump out of these, and a common use is to use a goto in place
* of a multi-level break
*/
static sxi32 PH7_CompileGoto(ph7_gen_state *pGen)
{
JumpFixup sJump;
sxi32 rc;
pGen->pIn++; /* Jump the 'goto' keyword */
if( pGen->pIn >= pGen->pEnd ){
/* Missing label */
rc = PH7_GenCompileError(pGen,E_ERROR,pGen->pIn->nLine,"goto: expecting a 'label_name'");
if( rc == SXERR_ABORT ){
/* Error count limit reached,abort immediately */
return SXERR_ABORT;
}
return SXRET_OK;
}
if( (pGen->pIn->nType & (PH7_TK_KEYWORD|PH7_TK_ID)) == 0 ){
rc = PH7_GenCompileError(pGen,E_ERROR,pGen->pIn->nLine,"goto: Invalid label name: '%z'",&pGen->pIn->sData);
if( rc == SXERR_ABORT ){
/* Error count limit reached,abort immediately */
return SXERR_ABORT;
}
}else{
SyString *pTarget = &pGen->pIn->sData;
GenBlock *pBlock;
char *zDup;
/* Prepare the jump destination */
sJump.nJumpType = PH7_OP_JMP;
sJump.nLine = pGen->pIn->nLine;
/* Duplicate label name */
zDup = SyMemBackendStrDup(&pGen->pVm->sAllocator,pTarget->zString,pTarget->nByte);
if( zDup == 0 ){
PH7_GenCompileError(&(*pGen),E_ERROR,pGen->pIn->nLine,"Fatal, PH7 is running out of memory");
return SXERR_ABORT;
}
SyStringInitFromBuf(&sJump.sLabel,zDup,pTarget->nByte);
pBlock = pGen->pCurrent;
while( pBlock ){
if( pBlock->iFlags & (GEN_BLOCK_FUNC|GEN_BLOCK_EXCEPTION) ){
break;
}
/* Point to the upper block */
pBlock = pBlock->pParent;
}
if( pBlock && pBlock->iFlags & GEN_BLOCK_EXCEPTION ){
rc = PH7_GenCompileError(pGen,E_ERROR,pGen->pIn->nLine,"goto inside try/catch block is disallowed");
if( rc == SXERR_ABORT ){
/* Error count limit reached,abort immediately */
return SXERR_ABORT;
}
}
if( pBlock && (pBlock->iFlags & GEN_BLOCK_FUNC)){
sJump.pFunc = (ph7_vm_func *)pBlock->pUserData;
}else{
sJump.pFunc = 0;
}
/* Emit the unconditional jump */
if( SXRET_OK == PH7_VmEmitInstr(pGen->pVm,PH7_OP_JMP,0,0,0,&sJump.nInstrIdx) ){
SySetPut(&pGen->aGoto,(const void *)&sJump);
}
}
pGen->pIn++; /* Jump the label name */
if( pGen->pIn < pGen->pEnd && (pGen->pIn->nType & PH7_TK_SEMI) == 0 ){
PH7_GenCompileError(&(*pGen),E_ERROR,pGen->pIn->nLine,"Expected semi-colon ';' after 'goto' statement");
}
/* Statement successfully compiled */
return SXRET_OK;
}
/*
* Point to the next PHP chunk that will be processed shortly.
* Return SXRET_OK on success. Any other return value indicates
@ -3772,7 +3539,6 @@ static sxi32 GenStateCompileFuncBody(
{
SySet *pInstrContainer; /* Instruction container */
GenBlock *pBlock;
sxu32 nGotoOfft;
sxi32 rc;
/* Attach the new function */
rc = GenStateEnterBlock(&(*pGen),GEN_BLOCK_PROTECTED|GEN_BLOCK_FUNC,PH7_VmInstrLength(pGen->pVm),pFunc,&pBlock);
@ -3781,7 +3547,6 @@ static sxi32 GenStateCompileFuncBody(
/* Don't worry about freeing memory, everything will be released shortly */
return SXERR_ABORT;
}
nGotoOfft = SySetUsed(&pGen->aGoto);
/* Swap bytecode containers */
pInstrContainer = PH7_VmGetByteCodeContainer(pGen->pVm);
PH7_VmSetByteCodeContainer(pGen->pVm,&pFunc->aByteCode);
@ -3791,11 +3556,6 @@ static sxi32 GenStateCompileFuncBody(
GenStateFixJumps(pGen->pCurrent,PH7_OP_THROW,PH7_VmInstrLength(pGen->pVm));
/* Emit the final return if not yet done */
PH7_VmEmitInstr(pGen->pVm,PH7_OP_DONE,0,0,0,0);
/* Fix gotos jumps now the destination is resolved */
if( SXERR_ABORT == GenStateFixGoto(&(*pGen),nGotoOfft) ){
rc = SXERR_ABORT;
}
SySetTruncate(&pGen->aGoto,nGotoOfft);
/* Restore the default container */
PH7_VmSetByteCodeContainer(pGen->pVm,pInstrContainer);
/* Leave function block */
@ -6091,7 +5851,6 @@ static const LangConstruct aLangConstruct[] = {
{ PH7_TKWRD_EXIT, PH7_CompileHalt }, /* exit language construct */
{ PH7_TKWRD_TRY, PH7_CompileTry }, /* try statement */
{ PH7_TKWRD_THROW, PH7_CompileThrow }, /* throw statement */
{ PH7_TKWRD_GOTO, PH7_CompileGoto }, /* goto statement */
{ PH7_TKWRD_CONST, PH7_CompileConstant }, /* const statement */
{ PH7_TKWRD_VAR, PH7_CompileVar }, /* var statement */
{ PH7_TKWRD_NAMESPACE, PH7_CompileNamespace }, /* namespace statement */
@ -6205,10 +5964,6 @@ static sxi32 GenStateCompileChunk(
*/
xCons = PH7_ErrorRecover;
}
}else if( (pGen->pIn->nType & PH7_TK_ID) && (&pGen->pIn[1] < pGen->pEnd)
&& (pGen->pIn[1].nType & PH7_TK_COLON /*':'*/) ){
/* Label found [i.e: Out: ],point to the routine responsible of compiling it */
xCons = PH7_CompileLabel;
}
if( xCons == 0 ){
/* Assume an expression an try to compile it */
@ -6305,12 +6060,6 @@ static sxi32 PH7_CompilePHP(
/* Fix exceptions jumps */
GenStateFixJumps(pGen->pCurrent,PH7_OP_THROW,PH7_VmInstrLength(pGen->pVm));
/* Fix gotos now, the jump destination is resolved */
if( SXERR_ABORT == GenStateFixGoto(&(*pGen),0) ){
rc = SXERR_ABORT;
}
/* Reset container */
SySetReset(&pGen->aGoto);
SySetReset(&pGen->aLabel);
/* Compilation result */
return rc;
}
@ -6423,8 +6172,6 @@ PH7_PRIVATE sxi32 PH7_InitCodeGenerator(
pGen->pVm = &(*pVm);
pGen->xErr = xErr;
pGen->pErrData = pErrData;
SySetInit(&pGen->aLabel,&pVm->sAllocator,sizeof(Label));
SySetInit(&pGen->aGoto,&pVm->sAllocator,sizeof(JumpFixup));
SyHashInit(&pGen->hLiteral,&pVm->sAllocator,0,0);
SyHashInit(&pGen->hVar,&pVm->sAllocator,0,0);
/* Error log buffer */
@ -6449,8 +6196,6 @@ PH7_PRIVATE sxi32 PH7_ResetCodeGenerator(
ph7_gen_state *pGen = &pVm->sCodeGen;
GenBlock *pBlock,*pParent;
/* Reset state */
SySetReset(&pGen->aLabel);
SySetReset(&pGen->aGoto);
SyBlobRelease(&pGen->sErrBuf);
SyBlobRelease(&pGen->sWorker);
/* Point to the global scope */


+ 0
- 1
lex.c View File

@ -619,7 +619,6 @@ static sxu32 KeywordCode(const char *z, int n){
{"eval", PH7_TKWRD_EVAL},
{"do", PH7_TKWRD_DO},
{"exit", PH7_TKWRD_EXIT},
{"goto", PH7_TKWRD_GOTO},
{"implements", PH7_TKWRD_IMPLEMENTS},
{"include_once", PH7_TKWRD_INCONCE},
{"include", PH7_TKWRD_INCLUDE},


+ 0
- 2
ph7int.h View File

@ -1006,8 +1006,6 @@ struct ph7_gen_state
GenBlock sGlobal; /* Global block */
ProcConsumer xErr; /* Error consumer callback */
void *pErrData; /* Third argument to xErr() */
SySet aLabel; /* Label table */
SySet aGoto; /* Gotos table */
SyBlob sWorker; /* General purpose working buffer */
SyBlob sErrBuf; /* Error buffer */
SyToken *pIn; /* Current processed token */


Loading…
Cancel
Save