Ping for this patch kit: https://gcc.gnu.org/ml/gcc-patches/2017-11/msg00880.html
(and thanks again for looking at patch 2 earlier) On Thu, 2017-11-30 at 14:17 -0500, David Malcolm wrote: > Ping for the rest of this kit: > https://gcc.gnu.org/ml/gcc-patches/2017-11/msg00880.html > > (thanks for the review of patch 2 of the kit) > > On Fri, 2017-11-10 at 16:45 -0500, David Malcolm wrote: > > On Thu, 2017-11-02 at 10:46 -0400, Jason Merrill wrote: > > > On Tue, Oct 31, 2017 at 5:09 PM, David Malcolm <dmalcolm@redhat.c > > > om > > > > > > > > > > wrote: > > > > On Tue, 2017-10-24 at 09:53 -0400, Jason Merrill wrote: > > > > > On Fri, Oct 20, 2017 at 5:53 PM, David Malcolm <dmalcolm@redh > > > > > at > > > > > .c > > > > > om> > > > > > wrote: > > > > > > Design questions: > > > > > > > > > > > > * The patch introduces a new kind of tree node, currently > > > > > > called > > > > > > DECL_WRAPPER_EXPR (although it's used for wrapping > > > > > > constants > > > > > > as > > > > > > well > > > > > > as decls). Should wrappers be a new kind of tree node, > > > > > > or > > > > > > should > > > > > > they > > > > > > reuse an existing TREE_CODE? (e.g. NOP_EXPR, > > > > > > CONVERT_EXPR, > > > > > > etc). > > > > > > * NOP_EXPR: seems to be for use as an rvalue > > > > > > * CONVERT_EXPR: for type conversions > > > > > > * NON_LVALUE_EXPR: "Value is same as argument, but > > > > > > guaranteed > > > > > > not an > > > > > > lvalue" > > > > > > * but we *do* want to support lvalues here > > > > > > > > > > I think using NON_LVALUE_EXPR for constants would be > > > > > appropriate. > > > > > > > > > > > * VIEW_CONVERT_EXPR: viewing one thing as of a > > > > > > different > > > > > > type > > > > > > * can it support lvalues? > > > > > > > > > > Yes, the purpose of VIEW_CONVERT_EXPR is to support lvalues, > > > > > it > > > > > seems > > > > > like the right choice. > > > > > > > > > > Jason > > > > > > > > Thanks. I've been working on a new version of the patch using > > > > those > > > > tree codes, but have run into an issue. > > > > > > > > In g++.dg/conversion/reinterpret1.C: > > > > > > > > // PR c++/15076 > > > > > > > > struct Y { Y(int &); }; > > > > > > > > int v; > > > > Y y1(reinterpret_cast<int>(v)); // { dg-error "" } > > > > > > > > With trunk, this successfully generates an error: > > > > > > > > reinterpret1.C:6:6: error: cannot bind non-const lvalue > > > > reference > > > > of type ‘int&’ to an rvalue of type ‘int’ > > > > Y y1(reinterpret_cast<int>(v)); // { dg-error "" } > > > > ^~~~~~~~~~~~~~~~~~~~~~~~ > > > > reinterpret1.C:3:12: note: initializing argument 1 of > > > > ‘Y::Y(int&)’ > > > > struct Y { Y(int &); }; > > > > ^ > > > > > > > > where internally there's a NON_LVALUE_EXPR around a VAR_DECL, > > > > where > > > > both have the same type: > > > > > > > > (gdb) call debug_tree (expr) > > > > <non_lvalue_expr 0x7ffff145f6e0 > > > > type <integer_type 0x7ffff132e5e8 int public type_6 SI > > > > size <integer_cst 0x7ffff1331120 constant 32> > > > > unit-size <integer_cst 0x7ffff1331138 constant 4> > > > > align:32 warn_if_not_align:0 symtab:0 alias-set -1 > > > > canonical-type 0x7ffff132e5e8 precision:32 min <integer_cst > > > > 0x7ffff13310d8 -2147483648> max <integer_cst 0x7ffff13310f0 > > > > 2147483647> > > > > pointer_to_this <pointer_type 0x7ffff1336a80> > > > > reference_to_this <reference_type 0x7ffff144ca80>> > > > > > > > > arg:0 <var_decl 0x7ffff7ffbd80 v type <integer_type > > > > 0x7ffff132e5e8 int> > > > > used public static tree_1 read SI /home/david/coding- > > > > 3/gcc- > > > > git-expr-vs- > > > > decl/src/gcc/testsuite/g++.dg/conversion/reinterpret1.C:5:5 > > > > size > > > > <integer_cst 0x7ffff1331120 32> unit-size <integer_cst > > > > 0x7ffff1331138 4> > > > > align:32 warn_if_not_align:0 context > > > > <translation_unit_decl > > > > 0x7ffff131e168 /home/david/coding-3/gcc-git-expr-vs- > > > > decl/src/gcc/testsuite/g++.dg/conversion/reinterpret1.C> > > > > chain <type_decl 0x7ffff141a720 Y type <record_type > > > > 0x7ffff144c150 Y> > > > > public decl_2 VOID /home/david/coding-3/gcc-git- > > > > expr- > > > > vs-decl/src/gcc/testsuite/g++.dg/conversion/reinterpret1.C:3:8 > > > > align:8 warn_if_not_align:0 context > > > > <translation_unit_decl 0x7ffff131e168 /home/david/coding-3/gcc- > > > > git- > > > > expr-vs- > > > > decl/src/gcc/testsuite/g++.dg/conversion/reinterpret1.C> > > > > chain <function_decl 0x7ffff144f800 __cxa_call_unexpected>>> > > > > /home/david/coding-3/gcc-git-expr-vs- > > > > decl/src/gcc/testsuite/g++.dg/conversion/reinterpret1.C:6:6 > > > > start: > > > > /home/david/coding-3/gcc-git-expr-vs- > > > > decl/src/gcc/testsuite/g++.dg/conversion/reinterpret1.C:6:6 > > > > finish: > > > > /home/david/coding-3/gcc-git-expr-vs- > > > > decl/src/gcc/testsuite/g++.dg/conversion/reinterpret1.C:6:29> > > > > > > > > The problem is that this reinterpret cast "looks" just like one > > > > of > > > > my > > > > location wrappers. > > > > > > Your code shouldn't strip a NON_LVALUE_EXPR around a VAR_DECL. > > > > I see a similar issue with constants, where with: > > > > > > > > struct Y { Y(int &); }; > > > > Y y1(reinterpret_cast<int>(42)); > > > > > > > > trunk generates an error like the above, but my code handles > > > > the > > > > NON_LVALUE_EXPR<int>(INTEGER_CST<int>(42)) > > > > as if it were a location wrapper around the INTEGER_CST, and > > > > thus > > > > doesn't emit the error. > > > > > > Why doesn't it emit the error? We should get the same error > > > whether > > > or not we strip the wrapper. > > > > Thanks: my stripping macro was over-zealous: it was stripping any > > NON_LVALUE_EXPR or VIEW_CONVERT_EXPR where the type matched that of > > the wrapped node. I've added the additional condition that a > > NON_LVALUE_EXPR has to be around a CONSTANT_CLASS_P, and > > a VIEW_CONVERT_EXPR around a !CONSTANT_CLASS_P. > > > > Here's an updated version of the patch (v2), now a patch kit (on > > top > > of r254387). I split it up thematically for ease of review, but > > all > > the patches go together. > > > > This version of the patch kit bootstraps and passes the regression > > tests (on x86_64-pc-linux-gnu) > > > > To do so, I've made some simplfications to how wrappers nodes are > > added. > > > > The previous patch added wrappers in the C++ parser around > > constants > > and uses-of-declarations, along with some other places in the > > parser (typeid, alignof, sizeof, offsetof). > > > > This version takes a much more minimal approach: it only adds > > location wrapper nodes around the arguments at callsites, thus > > not adding wrapper nodes around uses of constants and decls in > > other > > locations. > > > > It keeps them for the other places in the parser (typeid, alignof, > > sizeof, offsetof). > > > > In addition, for now, each site that adds wrapper nodes is guarded > > with !processing_template_decl, suppressing the creation of wrapper > > nodes when processing template declarations. This is to simplify > > the patch kit so that we don't have to support wrapper nodes during > > template expansion. > > > > With this, we get a big usability win: we always have a location_t > > for every argument at a callsite, and so various errors involving > > mismatching arguments are much easier to read (as the pertinent > > argument is underlined). > > > > I marked this as "PR 43486" as it's a big step towards solving that > > PR (which seeks to preserve locations all the way through to the > > middle end), but much more would need to be done to solve it: > > > > * this patch kit only adds wrappers to the C++ frontend, not to C > > > > * as noted above, location_t wrapper nodes are only added at > > arguments of callsites (and a few other places), with some > > restrictions. > > > > * none of the wrapper nodes survive past gimplification; > > it's not clear to me how best to preserve them into the > > middle-end. But even without doing so, we get the big usability > > win. > > > > The later parts of the patch kit add STRIP_ANY_LOCATION_WRAPPER > > uses > > in various places where the tree code of an expression is examined, > > so that such conditions use the code of the wrapped node, rather > > than that of the wrapper. One of the risks of the patch kit is > > that > > although the testsuite passes, there are probably places in our > > code > > which still need uses of STRIP_ANY_LOCATION_WRAPPER. > > > > > > Performance of the patch kit > > **************************** > > > > Benchmarking shows an apparent 2-3% in cc1plus wallclock compile- > > time > > for kdecore.cc -O3 -g: > > > > Compilation of kdecore.cc at -O3 with -g for x86_64-pc-linux-gnu: > > wall > > control: [56.55, 56.54, 56.68, 56.51, 56.45, 56.5, 56.45, > > 56.46, 56.49, 56.5, 56.42, 56.37, 56.41, 56.55] > > experiment: [57.32, 58.37, 58.17, 58.18, 58.78, 58.48, 57.99, > > 58.16, 58.14, 57.62, 58.36, 58.1, 57.71, 57.7] > > Min: 56.370000 -> 57.320000: 1.02x slower > > Avg: 56.491429 -> 58.077143: 1.03x slower > > Significant (t=-15.14) > > Stddev: 0.07655 -> 0.38426: 5.0199x larger > > > > although I'm not quite sure why; the difference is in "phase > > setup", > > which > > gains a large "wall" value (but not in usr or sys), whereas "phase > > parsing" > > is unaffected: > > > > unpatched: > > > > phase setup : 0.00 ( 0%) usr 0.02 ( 0%) sys 0.02 > > ( > > 0%) wall 1488 kB ( 0%) ggc > > phase parsing : 1.83 ( 4%) usr 0.82 (16%) sys 2.66 > > ( > > 5%) wall 156603 kB (12%) ggc > > phase lang. deferred : 0.30 ( 1%) usr 0.09 ( 2%) sys 0.38 > > ( > > 1%) wall 29861 kB ( 2%) ggc > > phase opt and generate : 48.09 (94%) usr 4.28 (81%) sys 52.55 > > (93%) wall 1085420 kB (84%) ggc > > phase last asm : 0.86 ( 2%) usr 0.05 ( 1%) sys 0.92 > > ( > > 2%) wall 15806 kB ( 1%) ggc > > phase finalize : 0.00 ( 0%) usr 0.01 ( 0%) sys 0.01 > > ( > > 0%) wall 0 kB ( 0%) ggc > > |name lookup : 0.30 ( 1%) usr 0.13 ( 2%) sys 0.21 > > ( > > 0%) wall 4955 kB ( 0%) ggc > > |overload resolution : 0.49 ( 1%) usr 0.06 ( 1%) sys 0.68 > > ( > > 1%) wall 27263 kB ( 2%) ggc > > garbage collection : 0.77 ( 2%) usr 0.00 ( 0%) sys 0.77 > > ( > > 1%) wall 0 kB ( 0%) ggc > > [...] > > TOTAL : 51.08 5.27 56.54 > > > > 1289189 kB > > > > patched: > > phase setup : 0.01 ( 0%) usr 0.03 ( 1%) sys 1.91 > > ( > > 3%) wall 1488 kB ( 0%) ggc > > phase parsing : 1.80 ( 4%) usr 0.84 (16%) sys 2.66 > > ( > > 5%) wall 158066 kB (12%) ggc > > phase lang. deferred : 0.29 ( 1%) usr 0.09 ( 2%) sys 0.39 > > ( > > 1%) wall 29861 kB ( 2%) ggc > > phase opt and generate : 48.09 (94%) usr 4.27 (81%) sys 52.52 > > (90%) wall 1085428 kB (84%) ggc > > phase last asm : 0.82 ( 2%) usr 0.05 ( 1%) sys 0.89 > > ( > > 2%) wall 15806 kB ( 1%) ggc > > phase finalize : 0.00 ( 0%) usr 0.01 ( 0%) sys 0.00 > > ( > > 0%) wall 0 kB ( 0%) ggc > > |name lookup : 0.29 ( 1%) usr 0.07 ( 1%) sys 0.36 > > ( > > 1%) wall 4955 kB ( 0%) ggc > > |overload resolution : 0.51 ( 1%) usr 0.07 ( 1%) sys 0.50 > > ( > > 1%) wall 27296 kB ( 2%) ggc > > garbage collection : 0.79 ( 2%) usr 0.00 ( 0%) sys 0.78 > > ( > > 1%) wall 0 kB ( 0%) ggc > > TOTAL : 51.01 5.29 58.37 > > > > 1290660 kB > > > > What's up with that "phase setup" change? Did I mess up my testing > > somehow? > > > > > > ...and a slight increase in GGC usage: > > > > Compilation of kdecore.cc at -O3 with -g for x86_64-pc-linux-gnu: > > ggc > > control: [1289179.0, 1289189.0, 1289170.0, 1289186.0, > > 1289194.0, 1289172.0, 1289176.0, 1289192.0, 1289189.0, 1289179.0, > > 1289172.0, 1289190.0, 1289169.0, 1289185.0] > > experiment: [1290654.0, 1290660.0, 1290655.0, 1290659.0, > > 1290631.0, 1290655.0, 1290650.0, 1290652.0, 1290642.0, 1290650.0, > > 1290658.0, 1290662.0, 1290638.0, 1290655.0] > > Mem max: 1289194.000 -> 1290662.000: 1.0011x larger > > > > (this is with stripped binaries, and --enable-checking=release) > > > > Testing with a simple file that includes all of the C++ standard > > library > > (but doesn't do anything with it) shows no change in time, and GGC > > usage > > in the parsing phase increasing 50kB from 149954 kB to 150004 kB. > > > > > > Next steps? > > *********** > > > > I'm working on extending the patch kit to add wrapper nodes at all > > constants and uses-of-decls in the C++ parser, but of course this > > could have some effect on time/memory, and require more uses of > > STRIP_ANY_LOCATION_WRAPPER. > > > > An alternative appoach is: > > > > "[PATCH] C++: use an optional vec<location_t> for callsites" > > https://gcc.gnu.org/ml/gcc-patches/2017-08/msg01392.html > > > > which eschews wrapper nodes in favor of duplicating the C > > frontend's > > workaround here (though Jason disliked this approach, when we > > discussed > > it at Cauldron). > > > > Thoughts? > > > > (I'm keen on getting *some* solution for providing location_t > > values > > for arguments at C++ callsites into gcc 8) > > > > > > David Malcolm (14): > > C++: preserve locations within build_address > > Support for adding and stripping location_t wrapper nodes > > C++: add location_t wrapper nodes during parsing (minimal impl) > > Update testsuite to show improvements > > tree.c: strip location wrappers from integer_zerop etc > > Fix Wsizeof-pointer-memaccess*.c > > reject_gcc_builtin: strip any location wrappers > > cp/tree.c: strip location wrappers in lvalue_kind > > Strip location wrappers in null_ptr_cst_p > > warn_for_memset: handle location wrappers > > Handle location wrappers in string_conv_p > > C++: introduce null_node_p > > c-format.c: handle location wrappers > > pp_c_cast_expression: don't print casts for location wrappers > > > > gcc/c-family/c-common.c | 3 + > > gcc/c-family/c-common.h | 1 + > > gcc/c-family/c-format.c | 9 +- > > gcc/c-family/c-pretty-print.c | 66 +++++- > > gcc/c-family/c-warn.c | 8 + > > gcc/cp/call.c | 6 +- > > gcc/cp/cp-tree.h | 13 ++ > > gcc/cp/cvt.c | 2 +- > > gcc/cp/error.c | 2 +- > > gcc/cp/except.c | 2 +- > > gcc/cp/parser.c | 30 ++- > > gcc/cp/tree.c | 2 + > > gcc/cp/typeck.c | 6 +- > > .../g++.dg/diagnostic/param-type-mismatch.C | 27 +-- > > .../g++.dg/plugin/diagnostic-test-expressions-1.C | 260 > > +++++++++++++-------- > > gcc/tree.c | 59 +++++ > > gcc/tree.h | 26 +++ > > 17 files changed, 392 insertions(+), 130 deletions(-) > >
