diff options
Diffstat (limited to 'gcc/stmt.c')
| -rw-r--r-- | gcc/stmt.c | 93 |
1 files changed, 67 insertions, 26 deletions
diff --git a/gcc/stmt.c b/gcc/stmt.c index 718f2558e7d..3c8e2863edd 100644 --- a/gcc/stmt.c +++ b/gcc/stmt.c @@ -403,6 +403,7 @@ static bool check_unique_operand_names (tree, tree); static char *resolve_operand_name_1 (char *, tree, tree); static void expand_null_return_1 (rtx); static enum br_predictor return_prediction (rtx); +static rtx shift_return_value (rtx); static void expand_value_return (rtx); static int tail_recursion_args (tree, tree); static void expand_cleanups (tree, int, int); @@ -2902,6 +2903,34 @@ return_prediction (rtx val) return PRED_NO_PREDICTION; } + +/* If the current function returns values in the most significant part + of a register, shift return value VAL appropriately. The mode of + the function's return type is known not to be BLKmode. */ + +static rtx +shift_return_value (rtx val) +{ + tree type; + + type = TREE_TYPE (DECL_RESULT (current_function_decl)); + if (targetm.calls.return_in_msb (type)) + { + rtx target; + HOST_WIDE_INT shift; + + target = DECL_RTL (DECL_RESULT (current_function_decl)); + shift = (GET_MODE_BITSIZE (GET_MODE (target)) + - BITS_PER_UNIT * int_size_in_bytes (type)); + if (shift > 0) + val = expand_binop (GET_MODE (target), ashl_optab, + gen_lowpart (GET_MODE (target), val), + GEN_INT (shift), target, 1, OPTAB_WIDEN); + } + return val; +} + + /* Generate RTL to return from the current function, with value VAL. */ static void @@ -3066,7 +3095,7 @@ expand_return (tree retval) { int i; unsigned HOST_WIDE_INT bitpos, xbitpos; - unsigned HOST_WIDE_INT big_endian_correction = 0; + unsigned HOST_WIDE_INT padding_correction = 0; unsigned HOST_WIDE_INT bytes = int_size_in_bytes (TREE_TYPE (retval_rhs)); int n_regs = (bytes + UNITS_PER_WORD - 1) / UNITS_PER_WORD; @@ -3083,25 +3112,33 @@ expand_return (tree retval) return; } - /* Structures whose size is not a multiple of a word are aligned - to the least significant byte (to the right). On a BYTES_BIG_ENDIAN - machine, this means we must skip the empty high order bytes when - calculating the bit offset. */ - if (BYTES_BIG_ENDIAN - && bytes % UNITS_PER_WORD) - big_endian_correction = (BITS_PER_WORD - ((bytes % UNITS_PER_WORD) - * BITS_PER_UNIT)); + /* If the structure doesn't take up a whole number of words, see + whether the register value should be padded on the left or on + the right. Set PADDING_CORRECTION to the number of padding + bits needed on the left side. + + In most ABIs, the structure will be returned at the least end of + the register, which translates to right padding on little-endian + targets and left padding on big-endian targets. The opposite + holds if the structure is returned at the most significant + end of the register. */ + if (bytes % UNITS_PER_WORD != 0 + && (targetm.calls.return_in_msb (TREE_TYPE (retval_rhs)) + ? !BYTES_BIG_ENDIAN + : BYTES_BIG_ENDIAN)) + padding_correction = (BITS_PER_WORD - ((bytes % UNITS_PER_WORD) + * BITS_PER_UNIT)); /* Copy the structure BITSIZE bits at a time. */ - for (bitpos = 0, xbitpos = big_endian_correction; + for (bitpos = 0, xbitpos = padding_correction; bitpos < bytes * BITS_PER_UNIT; bitpos += bitsize, xbitpos += bitsize) { /* We need a new destination pseudo each time xbitpos is - on a word boundary and when xbitpos == big_endian_correction + on a word boundary and when xbitpos == padding_correction (the first time through). */ if (xbitpos % BITS_PER_WORD == 0 - || xbitpos == big_endian_correction) + || xbitpos == padding_correction) { /* Generate an appropriate register. */ dst = gen_reg_rtx (word_mode); @@ -3128,21 +3165,25 @@ expand_return (tree retval) BITS_PER_WORD); } - /* Find the smallest integer mode large enough to hold the - entire structure and use that mode instead of BLKmode - on the USE insn for the return register. */ - for (tmpmode = GET_CLASS_NARROWEST_MODE (MODE_INT); - tmpmode != VOIDmode; - tmpmode = GET_MODE_WIDER_MODE (tmpmode)) - /* Have we found a large enough mode? */ - if (GET_MODE_SIZE (tmpmode) >= bytes) - break; + tmpmode = GET_MODE (result_rtl); + if (tmpmode == BLKmode) + { + /* Find the smallest integer mode large enough to hold the + entire structure and use that mode instead of BLKmode + on the USE insn for the return register. */ + for (tmpmode = GET_CLASS_NARROWEST_MODE (MODE_INT); + tmpmode != VOIDmode; + tmpmode = GET_MODE_WIDER_MODE (tmpmode)) + /* Have we found a large enough mode? */ + if (GET_MODE_SIZE (tmpmode) >= bytes) + break; - /* No suitable mode found. */ - if (tmpmode == VOIDmode) - abort (); + /* No suitable mode found. */ + if (tmpmode == VOIDmode) + abort (); - PUT_MODE (result_rtl, tmpmode); + PUT_MODE (result_rtl, tmpmode); + } if (GET_MODE_SIZE (tmpmode) < GET_MODE_SIZE (word_mode)) result_reg_mode = word_mode; @@ -3175,7 +3216,7 @@ expand_return (tree retval) val = force_not_mem (val); emit_queue (); /* Return the calculated value, doing cleanups first. */ - expand_value_return (val); + expand_value_return (shift_return_value (val)); } else { |
