[Shamelessly hijacking Andrew's thread about gimple.h refactoring, since this seems on-topic for that, and I'm keen to hear from Andrew on how the following would interact with his work - I *think* our two cleanups are orthogonal.
[This is a revised version of the patches sent as: http://gcc.gnu.org/ml/gcc-patches/2013-08/msg01788.html and http://gcc.gnu.org/ml/gcc-patches/2013-08/msg01954.html which got bogged down in discussion of hand-written GTY hooks. This patch series updates things to make use of the new support in gengtype for simple inheritance schemes] The gimple statement types are currently implemented using a hand-coded C inheritance scheme, with a "union gimple_statement_d" holding the various possible structs for a statement. The following series of patches convert it to a C++ hierarchy, using the existing structs, eliminating the union. The "gimple" typedef changes from being a (union gimple_statement_d *) to being a: (struct gimple_statement_base *) There are no virtual functions in the new code: the sizes of the various structs are unchanged. It makes use of "is-a.h", using the as_a <T> template function to perform downcasts, which are checked (via gcc_checking_assert) in an ENABLE_CHECKING build, and are simple casts in an unchecked build, albeit it in an inlined function rather than a macro. For example, one can write: gimple_statement_phi *phi = as_a <gimple_statement_phi> (gsi_stmt (gsi)); and then directly access the fields of the phi, as a phi. The existing accessor functions in gimple.h become somewhat redundant in this scheme, but are preserved. The earlier versions of the patches made all of the types GTY((user)) and provided hand-written implementations of the gc and pch marker routines. In this new version we rely on the support for simple inheritance that I recently added to gengtype, by adding a "desc" to the GTY marking for the base class, and a "tag" to the marking for all of the concrete subclasses. (I say "class", but all the types remain structs since their fields are all publicly accessible). As noted in the earlier patch, I believe this is a superior scheme to the C implementation: * We can get closer to compile-time type-safety, checking the gimple code once and downcasting with an as_a, then directly accessing fields, rather than going through accessor functions that check each time. In some places we may want to replace a "gimple" with a subclass e.g. phis are always of the phi subclass, to get full compile-time type-safety. * This scheme is likely to be easier for newbies to understand. * Currently in gdb, dereferencing a gimple leads to screenfuls of text, showing all the various union values. With this, you get just the base class, and can cast it to the appropriate subclass. * With this, we're working directly with the language constructs, rather than rolling our own, and thus other tools can better understand the code. (e.g. doxygen). Again, as noted in the earlier patch series, the names of the structs are rather verbose. I would prefer to also rename them all to eliminate the "_statement" component: "gimple_statement_base" -> "gimple_base" "gimple_statement_phi" -> "gimple_phi" "gimple_statement_omp" -> "gimple_omp" etc, but I didn't do this to mimimize the patch size. But if the core maintainers are up for that, I can redo the patch series with that change also, or do that as a followup. The patch is in 6 parts; all of them are needed together. * Patch 1 of 6: This patch adds inheritance to the various gimple types, eliminating the initial baseclass fields, and eliminating the union gimple_statement_d. All the types remain structs. They become marked with GTY(()), gaining GSS_ tag values. * Patch 2 of 6: This patch ports various accessor functions within gimple.h to the new scheme. * Patch 3 of 6: This patch is autogenerated by "refactor_gimple.py" from https://github.com/davidmalcolm/gcc-refactoring-scripts There is a test suite "test_refactor_gimple.py" which may give a clearer idea of the changes that the script makes (and add confidence that it's doing the right thing). The patch converts code of the form: { GIMPLE_CHECK (gs, SOME_CODE); gimple_subclass_get/set_some_field (gs, value); } to code of this form: { some_subclass *stmt = as_a <some_subclass> (gs); stmt->some_field = value; } It also autogenerates specializations of is_a_helper <T>::test equivalent to a GIMPLE_CHECK() for use by is_a and as_a. * Patch 4 of 6: This patch implement further specializations of is_a_helper <T>::test, for gimple_has_ops and gimple_has_mem_ops. * Patch 5 of 6: This patch does the rest of porting from union access to subclass access (all the fiddly places that the script in patch 3 couldn't handle). * Patch 6 of 6: This patch updates the gdb python pretty-printing hook. Successfully bootstrapped and tested on x86_64-unknown-linux-gnu: all testcases show the same results as an unpatched build (relative to r204230). OK for trunk? David Malcolm (6): Convert gimple types from a union to C++ inheritance Hand-written port of various accessors within gimple.h Automated part of conversion of gimple types to use C++ inheritance Implement is_a_helper <>::test specializations for various gimple types Port various places from union access to subclass access. Update gdb hooks to reflect changes to gimple types gcc/Makefile.in | 2 +- gcc/coretypes.h | 5 +- gcc/gdbhooks.py | 2 +- gcc/ggc.h | 6 +- gcc/gimple-iterator.c | 72 +- gcc/gimple-pretty-print.c | 6 +- gcc/gimple-pretty-print.h | 4 +- gcc/gimple-ssa.h | 16 +- gcc/gimple-streamer-in.c | 19 +- gcc/gimple-streamer-out.c | 2 +- gcc/gimple.c | 76 ++- gcc/gimple.h | 1651 +++++++++++++++++++++++++++++---------------- gcc/gimplify.c | 4 +- gcc/system.h | 2 +- gcc/tree-inline.c | 2 +- gcc/tree-phinodes.c | 39 +- gcc/tree-ssa-ccp.c | 2 +- 17 files changed, 1197 insertions(+), 713 deletions(-) -- 1.7.11.7
