diff options
| -rw-r--r-- | gcc/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/expr.c | 41 |
2 files changed, 46 insertions, 1 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 57e7201..d7c58a1 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2006-05-23 Joseph Myers <joseph@codesourcery.com> + + * expr.c (undefined_operand_subword_p): New. + (emit_move_multi_word): Do not generate move from undefined bits + of a paradoxical subreg. + 2006-05-23 Richard Sandiford <richard@codesourcery.com> PR rtl-optimization/27736 @@ -3096,6 +3096,38 @@ emit_move_ccmode (enum machine_mode mode, rtx x, rtx y) return ret; } +/* Return true if word I of OP lies entirely in the + undefined bits of a paradoxical subreg. */ + +static bool +undefined_operand_subword_p (rtx op, int i) +{ + enum machine_mode innermode, innermostmode; + int offset; + if (GET_CODE (op) != SUBREG) + return false; + innermode = GET_MODE (op); + innermostmode = GET_MODE (SUBREG_REG (op)); + offset = i * UNITS_PER_WORD + SUBREG_BYTE (op); + /* The SUBREG_BYTE represents offset, as if the value were stored in + memory, except for a paradoxical subreg where we define + SUBREG_BYTE to be 0; undo this exception as in + simplify_subreg. */ + if (SUBREG_BYTE (op) == 0 + && GET_MODE_SIZE (innermostmode) < GET_MODE_SIZE (innermode)) + { + int difference = (GET_MODE_SIZE (innermostmode) - GET_MODE_SIZE (innermode)); + if (WORDS_BIG_ENDIAN) + offset += (difference / UNITS_PER_WORD) * UNITS_PER_WORD; + if (BYTES_BIG_ENDIAN) + offset += difference % UNITS_PER_WORD; + } + if (offset >= GET_MODE_SIZE (innermostmode) + || offset <= -GET_MODE_SIZE (word_mode)) + return true; + return false; +} + /* A subroutine of emit_move_insn_1. Generate a move from Y into X. MODE is any multi-word or full-word mode that lacks a move_insn pattern. Note that you will get better code if you define such @@ -3133,7 +3165,14 @@ emit_move_multi_word (enum machine_mode mode, rtx x, rtx y) i++) { rtx xpart = operand_subword (x, i, 1, mode); - rtx ypart = operand_subword (y, i, 1, mode); + rtx ypart; + + /* Do not generate code for a move if it would come entirely + from the undefined bits of a paradoxical subreg. */ + if (undefined_operand_subword_p (y, i)) + continue; + + ypart = operand_subword (y, i, 1, mode); /* If we can't get a part of Y, put Y into memory if it is a constant. Otherwise, force it into a register. Then we must |