diff options
Diffstat (limited to 'gcc/optabs.c')
| -rw-r--r-- | gcc/optabs.c | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/gcc/optabs.c b/gcc/optabs.c index 32f397c..5ed8101 100644 --- a/gcc/optabs.c +++ b/gcc/optabs.c @@ -5120,10 +5120,11 @@ expand_float (rtx to, rtx from, int unsignedp) } } - /* Unsigned integer, and no way to convert directly. For binary - floating point modes, convert as signed, then conditionally adjust - the result. */ - if (unsignedp && can_do_signed && !DECIMAL_FLOAT_MODE_P (GET_MODE (to))) + /* Unsigned integer, and no way to convert directly. Convert as signed, + then unconditionally adjust the result. For decimal float values we + do this only if we have already determined that a signed conversion + provides sufficient accuracy. */ + if (unsignedp && (can_do_signed || !DECIMAL_FLOAT_MODE_P (GET_MODE (to)))) { rtx label = gen_label_rtx (); rtx temp; @@ -5214,7 +5215,7 @@ expand_float (rtx to, rtx from, int unsignedp) 0, label); - real_2expN (&offset, GET_MODE_BITSIZE (GET_MODE (from))); + real_2expN (&offset, GET_MODE_BITSIZE (GET_MODE (from)), fmode); temp = expand_binop (fmode, add_optab, target, CONST_DOUBLE_FROM_REAL_VALUE (offset, fmode), target, 0, OPTAB_LIB_WIDEN); @@ -5325,14 +5326,16 @@ expand_fix (rtx to, rtx from, int unsignedp) anything with a wider integer mode. This code used to extend FP value into mode wider than the destination. - This is not needed. Consider, for instance conversion from SFmode + This is needed for decimal float modes which cannot accurately + represent one plus the highest signed number of the same size, but + not for binary modes. Consider, for instance conversion from SFmode into DImode. The hot path through the code is dealing with inputs smaller than 2^63 and doing just the conversion, so there is no bits to lose. In the other path we know the value is positive in the range 2^63..2^64-1 - inclusive. (as for other imput overflow happens and result is undefined) + inclusive. (as for other input overflow happens and result is undefined) So we know that the most important bit set in mantissa corresponds to 2^63. The subtraction of 2^63 should not generate any rounding as it simply clears out that bit. The rest is trivial. */ @@ -5340,15 +5343,16 @@ expand_fix (rtx to, rtx from, int unsignedp) if (unsignedp && GET_MODE_BITSIZE (GET_MODE (to)) <= HOST_BITS_PER_WIDE_INT) for (fmode = GET_MODE (from); fmode != VOIDmode; fmode = GET_MODE_WIDER_MODE (fmode)) - if (CODE_FOR_nothing != can_fix_p (GET_MODE (to), fmode, 0, - &must_trunc)) + if (CODE_FOR_nothing != can_fix_p (GET_MODE (to), fmode, 0, &must_trunc) + && (!DECIMAL_FLOAT_MODE_P (fmode) + || GET_MODE_BITSIZE (fmode) > GET_MODE_BITSIZE (GET_MODE (to)))) { int bitsize; REAL_VALUE_TYPE offset; rtx limit, lab1, lab2, insn; bitsize = GET_MODE_BITSIZE (GET_MODE (to)); - real_2expN (&offset, bitsize - 1); + real_2expN (&offset, bitsize - 1, fmode); limit = CONST_DOUBLE_FROM_REAL_VALUE (offset, fmode); lab1 = gen_label_rtx (); lab2 = gen_label_rtx (); |