diff options
Diffstat (limited to 'gcc/expr.c')
| -rw-r--r-- | gcc/expr.c | 21 |
1 files changed, 21 insertions, 0 deletions
@@ -2767,6 +2767,7 @@ copy_blkmode_to_reg (machine_mode mode_in, tree src) /* No current ABI uses variable-sized modes to pass a BLKmnode type. */ fixed_size_mode mode = as_a <fixed_size_mode> (mode_in); fixed_size_mode dst_mode; + scalar_int_mode min_mode; gcc_assert (TYPE_MODE (TREE_TYPE (src)) == BLKmode); @@ -2796,6 +2797,7 @@ copy_blkmode_to_reg (machine_mode mode_in, tree src) n_regs = (bytes + UNITS_PER_WORD - 1) / UNITS_PER_WORD; dst_words = XALLOCAVEC (rtx, n_regs); bitsize = MIN (TYPE_ALIGN (TREE_TYPE (src)), BITS_PER_WORD); + min_mode = smallest_int_mode_for_size (bitsize); /* Copy the structure BITSIZE bits at a time. */ for (bitpos = 0, xbitpos = padding_correction; @@ -2816,6 +2818,25 @@ copy_blkmode_to_reg (machine_mode mode_in, tree src) emit_move_insn (dst_word, CONST0_RTX (word_mode)); } + /* Find the largest integer mode that can be used to copy all or as + many bits as possible of the structure if the target supports larger + copies. There are too many corner cases here w.r.t to alignments on + the read/writes. So if there is any padding just use single byte + operations. */ + opt_scalar_int_mode mode_iter; + if (padding_correction == 0 && !STRICT_ALIGNMENT) + { + FOR_EACH_MODE_FROM (mode_iter, min_mode) + { + unsigned int msize = GET_MODE_BITSIZE (mode_iter.require ()); + if (msize <= ((bytes * BITS_PER_UNIT) - bitpos) + && msize <= BITS_PER_WORD) + bitsize = msize; + else + break; + } + } + /* We need a new source operand each time bitpos is on a word boundary. */ if (bitpos % BITS_PER_WORD == 0) |