diff options
Diffstat (limited to 'gcc/stor-layout.c')
| -rw-r--r-- | gcc/stor-layout.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/gcc/stor-layout.c b/gcc/stor-layout.c index 76f27b2..fee26e6 100644 --- a/gcc/stor-layout.c +++ b/gcc/stor-layout.c @@ -2361,6 +2361,13 @@ fixup_unsigned_type (tree type) /* Find the best machine mode to use when referencing a bit field of length BITSIZE bits starting at BITPOS. + BITREGION_START is the bit position of the first bit in this + sequence of bit fields. BITREGION_END is the last bit in this + sequence. If these two fields are non-zero, we should restrict the + memory access to a maximum sized chunk of + BITREGION_END - BITREGION_START + 1. Otherwise, we are allowed to touch + any adjacent non bit-fields. + The underlying object is known to be aligned to a boundary of ALIGN bits. If LARGEST_MODE is not VOIDmode, it means that we should not use a mode larger than LARGEST_MODE (usually SImode). @@ -2378,11 +2385,21 @@ fixup_unsigned_type (tree type) decide which of the above modes should be used. */ enum machine_mode -get_best_mode (int bitsize, int bitpos, unsigned int align, +get_best_mode (int bitsize, int bitpos, + unsigned HOST_WIDE_INT bitregion_start, + unsigned HOST_WIDE_INT bitregion_end, + unsigned int align, enum machine_mode largest_mode, int volatilep) { enum machine_mode mode; unsigned int unit = 0; + unsigned HOST_WIDE_INT maxbits; + + /* If unset, no restriction. */ + if (!bitregion_end) + maxbits = MAX_FIXED_MODE_SIZE; + else + maxbits = (bitregion_end - bitregion_start) % align + 1; /* Find the narrowest integer mode that contains the bit field. */ for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode; @@ -2419,6 +2436,7 @@ get_best_mode (int bitsize, int bitpos, unsigned int align, && bitpos / unit == (bitpos + bitsize - 1) / unit && unit <= BITS_PER_WORD && unit <= MIN (align, BIGGEST_ALIGNMENT) + && unit <= maxbits && (largest_mode == VOIDmode || unit <= GET_MODE_BITSIZE (largest_mode))) wide_mode = tmode; |