| Message ID | 20200113085539.GG2416@tucnak |
|---|---|
| State | New |
| Headers | show |
| Series | Further bootstrap unbreak (was Re: [PATCH] PR90838: Support ctz idioms) | expand |
On Mon, 13 Jan 2020, Jakub Jelinek wrote: > On Sat, Jan 11, 2020 at 05:30:52PM +0100, Jakub Jelinek wrote: > > On Sat, Jan 11, 2020 at 05:24:19PM +0100, Andreas Schwab wrote: > > > ../../gcc/tree-ssa-forwprop.c: In function 'bool simplify_count_trailing_zeroes(gimple_stmt_iterator*)': > > > ../../gcc/tree-ssa-forwprop.c:1925:23: error: variable 'mode' set but not used [-Werror=unused-but-set-variable] > > > 1925 | scalar_int_mode mode = SCALAR_INT_TYPE_MODE (type); > > > | ^~~~ > > > > Oops, then I think we need following, but can't commit it until Monday. > > Unfortunately, at least when testing x86_64-linux to s390x-linux cross, > there are two warnings instead of just one: > ../../gcc/tree-ssa-forwprop.c: In function ‘bool simplify_count_trailing_zeroes(gimple_stmt_iterator*)’: > ../../gcc/tree-ssa-forwprop.c:1925:23: warning: variable ‘mode’ set but not used [-Wunused-but-set-variable] > scalar_int_mode mode = SCALAR_INT_TYPE_MODE (type); > ^~~~ > ../../gcc/tree-ssa-forwprop.c:1932:7: warning: ‘ctzval’ may be used uninitialized in this function [-Wmaybe-uninitialized] > if (zero_val != ctzval && !(zero_val == 0 && ctzval == type_size)) > ^~ > at -O0 and just the first one at -O2. > The first warning (or with error with -Werror) can be cured by the > patch I've posted on Saturday, I've successfully bootstrapped/regtested > it in the mean time on x86_64-linux and i686-linux, tested on aarch64-linux > including the testcase and tested on s390x-linux. > > Or we could also initialize ctzval as in the following patch to e.g. match > what we do in vr-values.c with *_DEFINED_VALUE_AT_ZERO. Except for the > x86_64-linux/i686-linux bootstrap/regtest, tested similarly to the above. > > So, ok for trunk and which one? OK, the one below looks good to me. > 2020-01-13 Jakub Jelinek <jakub@redhat.com> > > PR tree-optimization/90838 > * tree-ssa-forwprop.c (simplify_count_trailing_zeroes): Use > SCALAR_INT_TYPE_MODE directly in CTZ_DEFINED_VALUE_AT_ZERO macro > argument rather than to initialize temporary for targets that > don't use the mode argument at all. Initialize ctzval to avoid > warning at -O0. > > --- gcc/tree-ssa-forwprop.c > +++ gcc/tree-ssa-forwprop.c > @@ -1920,10 +1920,10 @@ simplify_count_trailing_zeroes (gimple_stmt_iterator *gsi) > res_ops[1], res_ops[2], zero_val)) > { > tree type = TREE_TYPE (res_ops[0]); > - HOST_WIDE_INT ctzval; > + HOST_WIDE_INT ctzval = 0; > HOST_WIDE_INT type_size = tree_to_shwi (TYPE_SIZE (type)); > - scalar_int_mode mode = SCALAR_INT_TYPE_MODE (type); > - bool zero_ok = CTZ_DEFINED_VALUE_AT_ZERO (mode, ctzval) == 2; > + bool zero_ok > + = CTZ_DEFINED_VALUE_AT_ZERO (SCALAR_INT_TYPE_MODE (type), ctzval) == 2; > > /* Skip if there is no value defined at zero, or if we can't easily > return the correct value for zero. */ > > Jakub
Hi Jakub, On Sat, Jan 11, 2020 at 05:30:52PM +0100, Jakub Jelinek wrote: > On Sat, Jan 11, 2020 at 05:24:19PM +0100, Andreas Schwab wrote: > > ../../gcc/tree-ssa-forwprop.c: In function 'bool simplify_count_trailing_zeroes(gimple_stmt_iterator*)': > > ../../gcc/tree-ssa-forwprop.c:1925:23: error: variable 'mode' set but not used [-Werror=unused-but-set-variable] > > 1925 | scalar_int_mode mode = SCALAR_INT_TYPE_MODE (type); > > | ^~~~ > > Oops, then I think we need following, but can't commit it until Monday. Thanks for sorting this out so quickly, Jakub! It looks like we need to convert these macros to targetm hooks given it's too difficult to get them to compile without warnings/errors... That would also allow us to fix the odd interface of CTZ_DEFINED_VALUE_AT_ZERO and remove the 1 vs 2 distinction. Cheers, Wilco
--- gcc/tree-ssa-forwprop.c +++ gcc/tree-ssa-forwprop.c @@ -1920,10 +1920,10 @@ simplify_count_trailing_zeroes (gimple_stmt_iterator *gsi) res_ops[1], res_ops[2], zero_val)) { tree type = TREE_TYPE (res_ops[0]); - HOST_WIDE_INT ctzval; + HOST_WIDE_INT ctzval = 0; HOST_WIDE_INT type_size = tree_to_shwi (TYPE_SIZE (type)); - scalar_int_mode mode = SCALAR_INT_TYPE_MODE (type); - bool zero_ok = CTZ_DEFINED_VALUE_AT_ZERO (mode, ctzval) == 2; + bool zero_ok + = CTZ_DEFINED_VALUE_AT_ZERO (SCALAR_INT_TYPE_MODE (type), ctzval) == 2; /* Skip if there is no value defined at zero, or if we can't easily return the correct value for zero. */