diff options
| -rw-r--r-- | gcc/cexp.y | 107 |
1 files changed, 88 insertions, 19 deletions
@@ -98,6 +98,14 @@ extern int traditional; #ifndef WCHAR_TYPE_SIZE #define WCHAR_TYPE_SIZE INT_TYPE_SIZE #endif + +/* Yield nonzero if adding two numbers with A's and B's signs can yield a + number with SUM's sign, where A, B, and SUM are all C integers. */ +#define possible_sum_sign(a, b, sum) ((((a) ^ (b)) | ~ ((a) ^ (sum))) < 0) + +static void integer_overflow (); +static long left_shift (); +static long right_shift (); %} %union { @@ -147,6 +155,8 @@ exp1 : exp /* Expressions, not including the comma operator. */ exp : '-' exp %prec UNARY { $$.value = - $2.value; + if (($$.value & $2.value) < 0 && ! $2.unsignedp) + integer_overflow (); $$.unsignedp = $2.unsignedp; } | '!' exp %prec UNARY { $$.value = ! $2.value; @@ -175,9 +185,15 @@ exp : '-' exp %prec UNARY exp : exp '*' exp { $$.unsignedp = $1.unsignedp || $3.unsignedp; if ($$.unsignedp) - $$.value = (unsigned) $1.value * $3.value; + $$.value = (unsigned long) $1.value * $3.value; else - $$.value = $1.value * $3.value; } + { + $$.value = $1.value * $3.value; + if ($1.value + && ($$.value / $1.value != $3.value + || ($$.value & $1.value & $3.value) < 0)) + integer_overflow (); + } } | exp '/' exp { if ($3.value == 0) { @@ -186,9 +202,13 @@ exp : exp '*' exp } $$.unsignedp = $1.unsignedp || $3.unsignedp; if ($$.unsignedp) - $$.value = (unsigned) $1.value / $3.value; + $$.value = (unsigned long) $1.value / $3.value; else - $$.value = $1.value / $3.value; } + { + $$.value = $1.value / $3.value; + if (($$.value & $1.value & $3.value) < 0) + integer_overflow (); + } } | exp '%' exp { if ($3.value == 0) { @@ -197,27 +217,35 @@ exp : exp '*' exp } $$.unsignedp = $1.unsignedp || $3.unsignedp; if ($$.unsignedp) - $$.value = (unsigned) $1.value % $3.value; + $$.value = (unsigned long) $1.value % $3.value; else $$.value = $1.value % $3.value; } | exp '+' exp { $$.value = $1.value + $3.value; - $$.unsignedp = $1.unsignedp || $3.unsignedp; } + $$.unsignedp = $1.unsignedp || $3.unsignedp; + if (! $$.unsignedp + && ! possible_sum_sign ($1.value, $3.value, + $$.value)) + integer_overflow (); } | exp '-' exp { $$.value = $1.value - $3.value; - $$.unsignedp = $1.unsignedp || $3.unsignedp; } + $$.unsignedp = $1.unsignedp || $3.unsignedp; + if (! $$.unsignedp + && ! possible_sum_sign ($$.value, $3.value, + $1.value)) + integer_overflow (); } | exp LSH exp { $$.unsignedp = $1.unsignedp; - if ($$.unsignedp) - $$.value = (unsigned) $1.value << $3.value; + if ($3.value < 0 && ! $3.unsignedp) + $$.value = right_shift (&$1, -$3.value); else - $$.value = $1.value << $3.value; } + $$.value = left_shift (&$1, $3.value); } | exp RSH exp { $$.unsignedp = $1.unsignedp; - if ($$.unsignedp) - $$.value = (unsigned) $1.value >> $3.value; + if ($3.value < 0 && ! $3.unsignedp) + $$.value = left_shift (&$1, -$3.value); else - $$.value = $1.value >> $3.value; } + $$.value = right_shift (&$1, $3.value); } | exp EQUAL exp { $$.value = ($1.value == $3.value); $$.unsignedp = 0; } @@ -227,25 +255,25 @@ exp : exp '*' exp | exp LEQ exp { $$.unsignedp = 0; if ($1.unsignedp || $3.unsignedp) - $$.value = (unsigned) $1.value <= $3.value; + $$.value = (unsigned long) $1.value <= $3.value; else $$.value = $1.value <= $3.value; } | exp GEQ exp { $$.unsignedp = 0; if ($1.unsignedp || $3.unsignedp) - $$.value = (unsigned) $1.value >= $3.value; + $$.value = (unsigned long) $1.value >= $3.value; else $$.value = $1.value >= $3.value; } | exp '<' exp { $$.unsignedp = 0; if ($1.unsignedp || $3.unsignedp) - $$.value = (unsigned) $1.value < $3.value; + $$.value = (unsigned long) $1.value < $3.value; else $$.value = $1.value < $3.value; } | exp '>' exp { $$.unsignedp = 0; if ($1.unsignedp || $3.unsignedp) - $$.value = (unsigned) $1.value > $3.value; + $$.value = (unsigned long) $1.value > $3.value; else $$.value = $1.value > $3.value; } | exp '&' exp @@ -548,10 +576,10 @@ yylex () if (lookup ("__CHAR_UNSIGNED__", sizeof ("__CHAR_UNSIGNED__")-1, -1) || ((result >> (num_bits - 1)) & 1) == 0) yylval.integer.value - = result & ((unsigned) ~0 >> (HOST_BITS_PER_INT - num_bits)); + = result & ((unsigned long) ~0 >> (HOST_BITS_PER_LONG - num_bits)); else yylval.integer.value - = result | ~((unsigned) ~0 >> (HOST_BITS_PER_INT - num_bits)); + = result | ~((unsigned long) ~0 >> (HOST_BITS_PER_LONG - num_bits)); } else { @@ -785,6 +813,47 @@ yyerror (s) error (s); longjmp (parse_return_error, 1); } + +static void +integer_overflow () +{ + pedwarn ("integer overflow in preprocessor expression"); +} + +static long +left_shift (a, b) + struct constant *a; + unsigned long b; +{ + if (b >= HOST_BITS_PER_LONG) + { + if (! a->unsignedp && a->value != 0) + integer_overflow (); + return 0; + } + else if (a->unsignedp) + return (unsigned long) a->value << b; + else + { + long l = a->value << b; + if (l >> b != a->value) + integer_overflow (); + return l; + } +} + +static long +right_shift (a, b) + struct constant *a; + unsigned long b; +{ + if (b >= HOST_BITS_PER_LONG) + return a->unsignedp ? 0 : a->value >> (HOST_BITS_PER_LONG - 1); + else if (a->unsignedp) + return (unsigned long) a->value >> b; + else + return a->value >> b; +} /* This page contains the entry point to this file. */ |