From cc1446556229298c9ab0d0e502f9298a23042c61 Mon Sep 17 00:00:00 2001 From: Gavin Romig-Koch Date: Wed, 21 Jul 1999 12:48:13 +0000 Subject: For gcc: * c-lex.c (yylex) : Correct the test for overflow when lexing integer literals. For gcc/cp: * lex.c (real_yylex) : Correct the test for overflow when lexing integer literals. From-SVN: r28206 --- gcc/c-lex.c | 46 +++++++++++++++++++++++++++------------------- 1 file changed, 27 insertions(+), 19 deletions(-) (limited to 'gcc/c-lex.c') diff --git a/gcc/c-lex.c b/gcc/c-lex.c index 252888d..52387f8 100644 --- a/gcc/c-lex.c +++ b/gcc/c-lex.c @@ -1477,16 +1477,19 @@ yylex () int count = 0; int largest_digit = 0; int numdigits = 0; - /* for multi-precision arithmetic, - we actually store only HOST_BITS_PER_CHAR bits in each part. - The number of parts is chosen so as to be sufficient to hold - the enough bits to fit into the two HOST_WIDE_INTs that contain - the integer value (this is always at least as many bits as are - in a target `long long' value, but may be wider). */ -#define TOTAL_PARTS ((HOST_BITS_PER_WIDE_INT / HOST_BITS_PER_CHAR) * 2 + 2) - int parts[TOTAL_PARTS]; int overflow = 0; + /* We actually store only HOST_BITS_PER_CHAR bits in each part. + The code below which fills the parts array assumes that a host + int is at least twice as wide as a host char, and that + HOST_BITS_PER_WIDE_INT is an even multiple of HOST_BITS_PER_CHAR. + Two HOST_WIDE_INTs is the largest int literal we can store. + In order to detect overflow below, the number of parts (TOTAL_PARTS) + must be exactly the number of parts needed to hold the bits + of two HOST_WIDE_INTs. */ +#define TOTAL_PARTS ((HOST_BITS_PER_WIDE_INT / HOST_BITS_PER_CHAR) * 2) + unsigned int parts[TOTAL_PARTS]; + enum anon1 { NOT_FLOAT, AFTER_POINT, TOO_MANY_POINTS, AFTER_EXPON} floatflag = NOT_FLOAT; @@ -1616,11 +1619,16 @@ yylex () else parts[0] += c; } - - /* If the extra highest-order part ever gets anything in it, - the number is certainly too big. */ - if (parts[TOTAL_PARTS - 1] != 0) - overflow = 1; + + /* If the highest-order part overflows (gets larger than + a host char will hold) then the whole number has + overflowed. Record this and truncate the highest-order + part. */ + if (parts[TOTAL_PARTS - 1] >> HOST_BITS_PER_CHAR) + { + overflow = 1; + parts[TOTAL_PARTS - 1] &= (1 << HOST_BITS_PER_CHAR) - 1; + } if (p >= token_buffer + maxtoken - 3) p = extend_token_buffer (p); @@ -1772,12 +1780,12 @@ yylex () c = GETC(); } - /* If it won't fit in the host's representation for integers, - then pedwarn. */ - - warn = overflow; - if (warn) - pedwarn ("integer constant is too large for this configuration of the compiler - truncated to %d bits", HOST_BITS_PER_WIDE_INT * 2); + /* If the literal overflowed, pedwarn about it now. */ + if (overflow) + { + warn = 1; + pedwarn ("integer constant is too large for this configuration of the compiler - truncated to %d bits", HOST_BITS_PER_WIDE_INT * 2); + } /* This is simplified by the fact that our constant is always positive. */ -- cgit v1.1