(expand_float): When converting an unsigned type U to a smaller or equal-sized floating type F where there's no hardware support for unsigned-to-float conversion...
(expand_float): When converting an unsigned type U to a smaller or equal-sized floating type F where there's no hardware support for unsigned-to-float conversion, use a temporary floating type larger than F if possible, since this avoids rounding problems that are worst when U is just greater than the maximum signed integer of the same size. From-SVN: r3778
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24
gcc/optabs.c
24
gcc/optabs.c
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@ -3572,11 +3572,27 @@ expand_float (to, from, unsignedp)
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if (flag_force_mem)
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from = force_not_mem (from);
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/* Look for a usable floating mode FMODE wider than the source and at
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least as wide as the target. Using FMODE will avoid rounding woes
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with unsigned values greater than the signed maximum value. */
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for (fmode = GET_MODE (to); fmode != VOIDmode;
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fmode = GET_MODE_WIDER_MODE (fmode))
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if (GET_MODE_BITSIZE (GET_MODE (from)) < GET_MODE_BITSIZE (fmode)
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&& can_float_p (fmode, GET_MODE (from), 0) != CODE_FOR_nothing)
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break;
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if (fmode == VOIDmode)
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{
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/* There is no such mode. Pretend the target is wide enough.
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This may cause rounding problems, unfortunately. */
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fmode = GET_MODE (to);
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}
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/* If we are about to do some arithmetic to correct for an
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unsigned operand, do it in a pseudo-register. */
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if (GET_CODE (to) != REG || REGNO (to) <= LAST_VIRTUAL_REGISTER)
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target = gen_reg_rtx (GET_MODE (to));
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if (GET_MODE (to) != fmode
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|| GET_CODE (to) != REG || REGNO (to) <= LAST_VIRTUAL_REGISTER)
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target = gen_reg_rtx (fmode);
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/* Convert as signed integer to floating. */
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expand_float (target, from, 0);
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@ -3591,8 +3607,8 @@ expand_float (to, from, unsignedp)
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Rather than setting up a dconst_dot_5, let's hope SCO
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fixes the bug. */
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offset = REAL_VALUE_LDEXP (dconst1, GET_MODE_BITSIZE (GET_MODE (from)));
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temp = expand_binop (GET_MODE (to), add_optab, target,
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immed_real_const_1 (offset, GET_MODE (to)),
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temp = expand_binop (fmode, add_optab, target,
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immed_real_const_1 (offset, fmode),
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target, 0, OPTAB_LIB_WIDEN);
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if (temp != target)
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emit_move_insn (target, temp);
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