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Commit dbac4aff by Neil Booth Committed by Neil Booth
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cppexp.c: Redefine priority constants. 

        * cppexp.c: Redefine priority constants.
        (_cpp_parse_expr): Replace left and right priority scheme with
	single priority logic.  Move LOGICAL to same place as COMPARE.
	Remove bogus check for multiple unary +/- operators.

From-SVN: r32855
parent 9ee70313
Showing with 84 additions and 64 deletions
gcc/ChangeLog
2000-04-01 Neil Booth <NeilB@earthling.net>
* cppexp.c: Redefine priority constants.
(_cpp_parse_expr): Replace left and right priority scheme with
single priority logic. Move LOGICAL to same place as COMPARE.
Remove bogus check for multiple unary +/- operators.
2000-04-01 Neil Booth <NeilB@earthling.net>
* cppexp.c: (_cpp_parse_expr): Numerical constants are pushed
within the switch statement. Binary operations break out of
the switch naturally. '(' tokens handled by forcing
......
gcc/cppexp.c
......@@ -106,7 +106,7 @@ static struct operation lex PARAMS ((cpp_reader *, int));
struct operation
{
short op;
U_CHAR rprio; /* Priority of op (relative to it right operand). */
U_CHAR prio; /* Priority of op (relative to it right operand). */
U_CHAR flags;
U_CHAR unsignedp; /* true if value should be treated as unsigned */
HOST_WIDEST_INT value; /* The value logically "right" of op. */
......@@ -636,32 +636,60 @@ right_shift (pfile, a, unsignedp, b)
return a >> b;
}
/* These priorities are all even, so we can handle associatively. */
#define PAREN_INNER_PRIO 2
#define COMMA_PRIO 4
#define COND_PRIO (COMMA_PRIO+2)
#define OROR_PRIO (COND_PRIO+2)
#define ANDAND_PRIO (OROR_PRIO+2)
#define OR_PRIO (ANDAND_PRIO+2)
#define XOR_PRIO (OR_PRIO+2)
#define AND_PRIO (XOR_PRIO+2)
#define EQUAL_PRIO (AND_PRIO+2)
#define LESS_PRIO (EQUAL_PRIO+2)
#define SHIFT_PRIO (LESS_PRIO+2)
#define PLUS_PRIO (SHIFT_PRIO+2)
#define MUL_PRIO (PLUS_PRIO+2)
#define UNARY_PRIO (MUL_PRIO+2)
#define PAREN_OUTER_PRIO (UNARY_PRIO+2)
/* Operator precedence table.
After an operator is returned from the lexer, if it has priority less
than or equal to the operator on the top of the stack, we reduce the
stack one operator and repeat the test. As equal priorities reduce,
this is naturally left-associative.
We handle right-associative operators by clearing the lower bit of all
left-associative operators, and setting it for right-associative ones.
After the reduction phase, when an operator is pushed onto the stack,
its RIGHT_ASSOC bit is cleared. This means that at reduction time, a
right-associative operator of otherwise equal precedence to the
operator on the top of the stack will have a greater priority by 1,
avoiding a reduction pass and making the logic right-associative.
The remaining cases are '(' and ')'. We handle '(' by skipping the
reduction phase completely. ')' is given lower priority than
everything else, including '(', effectively forcing a reduction of the
parenthesised expression. If there is no matching '(', the expression
will be reduced to the beginning, the ')' pushed, and the reduction
pass forced by the next ')', or the end of the expression, will meet
it and output an appropriate error message. */
#define RIGHT_ASSOC 1
#define PREVENT_REDUCE_PRIO (0 << 1)
#define FORCE_REDUCE_PRIO (1 << 1)
#define CLOSE_PAREN_PRIO (2 << 1)
#define OPEN_PAREN_PRIO (3 << 1)
#define COMMA_PRIO (4 << 1)
#define COND_PRIO ((5 << 1) + RIGHT_ASSOC)
#define COLON_PRIO (6 << 1)
#define OROR_PRIO (7 << 1)
#define ANDAND_PRIO (8 << 1)
#define OR_PRIO (9 << 1)
#define XOR_PRIO (10 << 1)
#define AND_PRIO (11 << 1)
#define EQUAL_PRIO (12 << 1)
#define LESS_PRIO (13 << 1)
#define SHIFT_PRIO (14 << 1)
#define PLUS_PRIO (15 << 1)
#define MUL_PRIO (16 << 1)
#define UNARY_PRIO ((17 << 1) + RIGHT_ASSOC)
#define LEFT_OPERAND_REQUIRED 1
#define RIGHT_OPERAND_REQUIRED 2
#define HAVE_VALUE 4
#define SIGN_QUALIFIED 8
#define COMPARE(OP) \
top->unsignedp = 0;\
top->value = (unsigned1 || unsigned2) \
? (unsigned HOST_WIDEST_INT) v1 OP (unsigned HOST_WIDEST_INT) v2 : (v1 OP v2)
#define LOGICAL(OP) \
top->value = v1 OP v2;\
top->unsignedp = unsigned1 || unsigned2;
/* Parse and evaluate a C expression, reading from PFILE.
Returns the truth value of the expression. */
......@@ -685,16 +713,16 @@ _cpp_parse_expr (pfile)
struct operation *stack = init_stack;
struct operation *limit = stack + INIT_STACK_SIZE;
register struct operation *top = stack;
unsigned int lprio, rprio = 0;
int skip_evaluation = 0;
long old_written = CPP_WRITTEN (pfile);
int result;
pfile->parsing_if_directive++;
top->rprio = 0;
top->prio = PREVENT_REDUCE_PRIO;
top->flags = 0;
for (;;)
{
unsigned int prio;
struct operation op;
U_CHAR flags = 0;
......@@ -730,59 +758,47 @@ _cpp_parse_expr (pfile)
continue;
case '+': case '-':
lprio = PLUS_PRIO;
prio = PLUS_PRIO;
if (top->flags & HAVE_VALUE)
break;
if (top->flags & SIGN_QUALIFIED)
{
cpp_error (pfile, "more than one sign operator given");
goto syntax_error;
}
flags = SIGN_QUALIFIED;
/* else fall through */
case '!': case '~':
flags |= RIGHT_OPERAND_REQUIRED;
rprio = UNARY_PRIO; lprio = rprio + 1; goto maybe_reduce;
case '*': case '/': case '%':
lprio = MUL_PRIO; break;
case '<': case '>': case LEQ: case GEQ:
lprio = LESS_PRIO; break;
case EQUAL: case NOTEQUAL:
lprio = EQUAL_PRIO; break;
case LSH: case RSH:
lprio = SHIFT_PRIO; break;
case '&': lprio = AND_PRIO; break;
case '^': lprio = XOR_PRIO; break;
case '|': lprio = OR_PRIO; break;
case ANDAND: lprio = ANDAND_PRIO; break;
case OROR: lprio = OROR_PRIO; break;
case ',':
lprio = COMMA_PRIO; break;
case '(':
lprio = PAREN_OUTER_PRIO; rprio = PAREN_INNER_PRIO + 1;
goto skip_reduction;
prio = UNARY_PRIO; goto maybe_reduce;
case '*':
case '/':
case '%': prio = MUL_PRIO; break;
case '<':
case '>':
case LEQ:
case GEQ: prio = LESS_PRIO; break;
case NOTEQUAL:
case EQUAL: prio = EQUAL_PRIO; break;
case LSH:
case RSH: prio = SHIFT_PRIO; break;
case '&': prio = AND_PRIO; break;
case '^': prio = XOR_PRIO; break;
case '|': prio = OR_PRIO; break;
case ANDAND: prio = ANDAND_PRIO; break;
case OROR: prio = OROR_PRIO; break;
case ',': prio = COMMA_PRIO; break;
case '(': prio = OPEN_PAREN_PRIO; goto skip_reduction;
case ')':
lprio = PAREN_INNER_PRIO; rprio = PAREN_OUTER_PRIO;
prio = CLOSE_PAREN_PRIO;
flags = HAVE_VALUE; /* At least, we will have after reduction. */
goto maybe_reduce;
case ':':
lprio = COND_PRIO; rprio = COND_PRIO + 1;
goto maybe_reduce;
case '?':
lprio = COND_PRIO; rprio = COND_PRIO;
goto maybe_reduce;
case 0:
lprio = 0; goto maybe_reduce;
case ':': prio = COLON_PRIO; goto maybe_reduce;
case '?': prio = COND_PRIO; goto maybe_reduce;
case 0: prio = FORCE_REDUCE_PRIO; goto maybe_reduce;
}
/* Binary operation. */
flags = LEFT_OPERAND_REQUIRED|RIGHT_OPERAND_REQUIRED;
rprio = lprio + 1;
maybe_reduce:
/* Push an operator, and check if we can reduce now. */
while (top->rprio > lprio)
/* Check for reductions. Then push the operator. */
while (prio <= top->prio)
{
HOST_WIDEST_INT v1 = top[-1].value, v2 = top[0].value;
unsigned int unsigned1 = top[-1].unsignedp;
......@@ -932,9 +948,6 @@ _cpp_parse_expr (pfile)
else
top->value = right_shift (pfile, v1, unsigned1, v2);
break;
#define LOGICAL(OP) \
top->value = v1 OP v2;\
top->unsignedp = unsigned1 || unsigned2;
case '&': LOGICAL(&); break;
case '^': LOGICAL(^); break;
case '|': LOGICAL(|); break;
......@@ -953,7 +966,7 @@ _cpp_parse_expr (pfile)
top->unsignedp = unsigned2;
break;
case '?':
cpp_error (pfile, "syntax error in #if");
cpp_error (pfile, "syntax error '?' without following ':'");
goto syntax_error;
case ':':
if (top[0].op != '?')
......@@ -1027,7 +1040,7 @@ _cpp_parse_expr (pfile)
}
top->flags = flags;
top->rprio = rprio;
top->prio = prio & ~RIGHT_ASSOC;
top->op = op.op;
/* Handle short circuiting. */
......
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