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(loop_iterations): When computing comparison_value, use 

reg_set_p to identify instructions that modify it.

From-SVN: r4036
This commit is contained in:
Jim Wilson 1993-04-06 12:38:34 -07:00
parent fdd79c58a2
commit 1f1e8172a8
1 changed files with 11 additions and 6 deletions
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17
gcc/unroll.c
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@ -3039,14 +3039,19 @@ loop_iterations (loop_start, loop_end)
break;
else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
&& (set = single_set (insn))
&& (SET_DEST (set) == comparison_value))
&& reg_set_p (comparison_value, insn))
{
rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST)
comparison_value = XEXP (note, 0);
/* We found the last insn before the loop that sets the register.
If it sets the entire register, and has a REG_EQUAL note,
then use the value of the REG_EQUAL note. */
if ((set = single_set (insn))
&& (SET_DEST (set) == comparison_value))
{
rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST)
comparison_value = XEXP (note, 0);
}
break;
}
}