| Message ID | 20140108094707.GC892@tucnak.redhat.com |
|---|---|
| State | New |
| Headers | show |
On Wed, 8 Jan 2014, Jakub Jelinek wrote: > Hi! > > The recent change to get_mode_bounds for partial mode, where > GET_MODE_PRECISION instead of GET_MODE_SIZE is now used, has broken > ia64 bootstrap. The problem is that BImode is special cased in various > places, e.g. trunc_int_for_mode, so the two values of the mode are > 0 and STORE_FLAG_VALUE (which is sometimes -1, sometimes (ia64 case) 1). > > Now, two of the 3 get_mode_bounds callers use the same mode == target_mode > and when called with BImode, true, BImode, ... min_val is -1 and max_val is 0, > but given the weirdo trunc_int_for_mode behavior which returns > STORE_FLAG_VALUE for value with low bit set and 0 otherwise, get_mode_bounds > actually returns min_rtx (const_int 1) and max_rtx (const_int 0). > This confuses the callers (in this case simplify-rtx.c) which then compares > the trueop1 value against the bounds to miscompile the code. > > This patch fixes this by special casing BImode, so that we get the bounds > in the right order for BImode, ?, BImode and even for the case where > target_mode is wider ignores sign and returns 0, STORE_FLAG_VALUE or vice > versa in the right order. > > Eric has kindly tested this on ia64. Ok for trunk? Ok. Thanks, Richard. > 2014-01-08 Jakub Jelinek <jakub@redhat.com> > > PR rtl-optimization/59649 > * stor-layout.c (get_mode_bounds): For BImode return > 0 and STORE_FLAG_VALUE. > > --- gcc/stor-layout.c.jj 2014-01-03 11:40:57.000000000 +0100 > +++ gcc/stor-layout.c 2014-01-07 18:59:39.056846684 +0100 > @@ -2821,7 +2821,21 @@ get_mode_bounds (enum machine_mode mode, > > gcc_assert (size <= HOST_BITS_PER_WIDE_INT); > > - if (sign) > + /* Special case BImode, which has values 0 and STORE_FLAG_VALUE. */ > + if (mode == BImode) > + { > + if (STORE_FLAG_VALUE < 0) > + { > + min_val = STORE_FLAG_VALUE; > + max_val = 0; > + } > + else > + { > + min_val = 0; > + max_val = STORE_FLAG_VALUE; > + } > + } > + else if (sign) > { > min_val = -((unsigned HOST_WIDE_INT) 1 << (size - 1)); > max_val = ((unsigned HOST_WIDE_INT) 1 << (size - 1)) - 1; > > Jakub > >
--- gcc/stor-layout.c.jj 2014-01-03 11:40:57.000000000 +0100 +++ gcc/stor-layout.c 2014-01-07 18:59:39.056846684 +0100 @@ -2821,7 +2821,21 @@ get_mode_bounds (enum machine_mode mode, gcc_assert (size <= HOST_BITS_PER_WIDE_INT); - if (sign) + /* Special case BImode, which has values 0 and STORE_FLAG_VALUE. */ + if (mode == BImode) + { + if (STORE_FLAG_VALUE < 0) + { + min_val = STORE_FLAG_VALUE; + max_val = 0; + } + else + { + min_val = 0; + max_val = STORE_FLAG_VALUE; + } + } + else if (sign) { min_val = -((unsigned HOST_WIDE_INT) 1 << (size - 1)); max_val = ((unsigned HOST_WIDE_INT) 1 << (size - 1)) - 1;