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flow.c (life_analysis): Delete obvious no-op moves which use SUBREGs.

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* flow.c (life_analysis): Delete obvious no-op moves
        which use SUBREGs.

From-SVN: r13607
This commit is contained in:
Jeff Law 1997-02-04 16:36:26 -07:00
parent f19911e44a
commit ac684a206c
1 changed files with 17 additions and 0 deletions
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17
gcc/flow.c
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@ -996,6 +996,23 @@ life_analysis (f, nregs)
NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
NOTE_SOURCE_FILE (insn) = 0;
}
/* Delete (in effect) any obvious no-op moves. */
else if (GET_CODE (PATTERN (insn)) == SET
&& GET_CODE (SET_DEST (PATTERN (insn))) == SUBREG
&& GET_CODE (SUBREG_REG (SET_DEST (PATTERN (insn)))) == REG
&& GET_CODE (SET_SRC (PATTERN (insn))) == SUBREG
&& GET_CODE (SUBREG_REG (SET_SRC (PATTERN (insn)))) == REG
&& REGNO (SUBREG_REG (SET_DEST (PATTERN (insn)))) ==
REGNO (SUBREG_REG (SET_SRC (PATTERN (insn))))
&& SUBREG_WORD (SET_DEST (PATTERN (insn))) ==
SUBREG_WORD (SET_SRC (PATTERN (insn)))
/* Insns carrying these notes are useful later on. */
&& ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
{
PUT_CODE (insn, NOTE);
NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
NOTE_SOURCE_FILE (insn) = 0;
}
else if (GET_CODE (PATTERN (insn)) == PARALLEL)
{
/* If nothing but SETs of registers to themselves,