On 2019-12-18 6:02 a.m., Richard Biener wrote:
> On December 17, 2019 8:31:00 PM GMT+01:00, Erick Ochoa
> <erick.oc...@theobroma-systems.com> wrote:
>> Hi,
>>
>> I'm interested in printing VAR_DECL trees that are of type
>> RECORD_TYPE. I am using the function print_generic_decl
>> for debugging and found this interesting behaviour.
>>
>> When I do initialization of structs using the following
>> syntax:
>>
>> ```
>> struct aStruct { _Bool e; int a; char b; float c; double d; _Bool f;
>> long h;};
>> struct aStruct astruct = { .e = 0, .a = 1, .b = 2, .c = 3.0, .d = 4.0,
>> .f = 5, .h = 6 };
>> ```
>>
>> print_generic_decl will print the following output:
>>
>> ```
>> INTERESTED IN: static struct aStruct astruct = <<< error >>>;
>> ```
>>
>> Am I using the correct API? Is this a limitation of the API?
>
> You need to ask IPA about the static initializer, DECL_INITIAL is adjusted at
> some point.
>
> Richard.
Thanks Richard.
I still don't understand very well what I should do. I found the
place in GCC internals where DECL_INITIAL is described.
https://gcc.gnu.org/onlinedocs/gccint/Working-with-declarations.html
VAR_DECL
If this variable is initialized (but does not require a constructor),
the DECL_INITIAL will be an expression for the initializer.
The initializer should be evaluated, and a bitwise copy into the variable
performed. If the DECL_INITIAL is the error_mark_node, there is an
initializer,
but it is given by an explicit statement later in the code; no bitwise copy
is required.
So, now I understand that I can now change my patch to something like this:
>> +iphw_execute()
>> +{
>> + if (!dump_file) return 0;
>> + varpool_node *node;
>> + FOR_EACH_VARIABLE(node)
>> + {
>> + gcc_assert(node->decl);
>> + tree decl = node->decl;
>> + gcc_assert(TREE_CODE(decl) == VAR_DECL);
>> +
>> + tree curr_type = TREE_TYPE(decl);
>> + gcc_assert(curr_type);
>> +
>> + const bool is_struct = TREE_CODE(curr_type) == RECORD_TYPE;
>> + if (is_struct) fprintf(dump_file, "INTERESTED IN: ");
tree expr = DECL_INITIAL(decl);
if (expr == error_mark_node) {
fprintf(dump_file, "initializer is given by explicit statement later
in code\n");
continue;
}
>> + print_generic_decl(dump_file, decl, TDF_DETAILS);
>> + fprintf(dump_file, "\n");
>> + }
However I still don't know how to ask IPA about the static initializer.
I tried iterating over the ipa_refs (i.e. node->iterate_referring (i, ref))
and then looking for writes, but there are now writes because it is a
initialized statically.
>
>> Would people be interested in me extending this API to print
>> out something more useful? I already have some code that
>> iterates over fields and prints out names and types. It
>> can still use some work though.
>>
>> However, I understand if this is the intended behaviour.
>> Another question (related to the possibility of intended behaviour)
>> is: how is struct initialization represented in trees?
>> (I.e. will each field be initialized separately or something else
>> happens?)
>>
>> Thanks! I also include the patch in case people want a simple
>> working example on how to print declarations.
>>
>> diff --git a/gcc/Makefile.in b/gcc/Makefile.in
>> index 6b857bd..f4f1376 100644
>> --- a/gcc/Makefile.in
>> +++ b/gcc/Makefile.in
>> @@ -1368,6 +1368,7 @@ OBJS = \
>> incpath.o \
>> init-regs.o \
>> internal-fn.o \
>> + ipa-hello-world.o \
>> ipa-cp.o \
>> ipa-sra.o \
>> ipa-devirt.o \
>> diff --git a/gcc/common.opt b/gcc/common.opt
>> index b4dc31c..304ec9f 100644
>> --- a/gcc/common.opt
>> +++ b/gcc/common.opt
>> @@ -3348,4 +3348,7 @@ fipa-ra
>> Common Report Var(flag_ipa_ra) Optimization
>> Use caller save register across calls if possible.
>>
>> +fipa-typelist
>> +Common Report Var(flag_ipa_typelist) TBD
>> +
>> ; This comment is to ensure we retain the blank line above.
>> diff --git a/gcc/ipa-hello-world.c b/gcc/ipa-hello-world.c
>> new file mode 100644
>> index 0000000..ed4ae11
>> --- /dev/null
>> +++ b/gcc/ipa-hello-world.c
>> @@ -0,0 +1,78 @@
>> +#include "config.h"
>> +#include "system.h"
>> +#include "coretypes.h"
>> +#include "backend.h"
>> +#include "tree.h"
>> +#include "gimple-expr.h"
>> +#include "predict.h"
>> +#include "alloc-pool.h"
>> +#include "tree-pass.h"
>> +#include "cgraph.h"
>> +#include "diagnostic.h"
>> +#include "fold-const.h"
>> +#include "gimple-fold.h"
>> +#include "symbol-summary.h"
>> +#include "tree-vrp.h"
>> +#include "ipa-prop.h"
>> +#include "tree-pretty-print.h"
>> +#include "tree-inline.h"
>> +#include "ipa-fnsummary.h"
>> +#include "ipa-utils.h"
>> +#include "tree-ssa-ccp.h"
>> +#include "stringpool.h"
>> +#include "attribs.h"
>> +
>> +
>> +static unsigned int
>> +iphw_execute()
>> +{
>> + if (!dump_file) return 0;
>> + varpool_node *node;
>> + FOR_EACH_VARIABLE(node)
>> + {
>> + gcc_assert(node->decl);
>> + tree decl = node->decl;
>> + gcc_assert(TREE_CODE(decl) == VAR_DECL);
>> +
>> + tree curr_type = TREE_TYPE(decl);
>> + gcc_assert(curr_type);
>> +
>> + const bool is_struct = TREE_CODE(curr_type) == RECORD_TYPE;
>> + if (is_struct) fprintf(dump_file, "INTERESTED IN: ");
>> + print_generic_decl(dump_file, decl, TDF_DETAILS);
>> + fprintf(dump_file, "\n");
>> + }
>> + return 0;
>> +}
>> +
>> +namespace {
>> +const pass_data pass_data_ipa_hello_world =
>> +{
>> + SIMPLE_IPA_PASS,
>> + "hello_world",
>> + OPTGROUP_NONE,
>> + TV_NONE,
>> + (PROP_cfg | PROP_ssa),
>> + 0,
>> + 0,
>> + 0,
>> + 0,
>> +};
>> +
>> +class pass_ipa_hello_world : public simple_ipa_opt_pass
>> +{
>> +public:
>> + pass_ipa_hello_world (gcc::context *ctx)
>> + : simple_ipa_opt_pass(pass_data_ipa_hello_world, ctx)
>> + {}
>> +
>> + virtual bool gate(function*) { return flag_ipa_typelist; }
>> + virtual unsigned execute (function*) { return iphw_execute(); }
>> +};
>> +} // anon namespace
>> +
>> +simple_ipa_opt_pass*
>> +make_pass_ipa_hello_world (gcc::context *ctx)
>> +{
>> + return new pass_ipa_hello_world (ctx);
>> +}
>> diff --git a/gcc/passes.def b/gcc/passes.def
>> index 798a391..52cd14b 100644
>> --- a/gcc/passes.def
>> +++ b/gcc/passes.def
>> @@ -146,6 +146,7 @@ along with GCC; see the file COPYING3. If not see
>> NEXT_PASS (pass_ipa_profile);
>> NEXT_PASS (pass_ipa_icf);
>> NEXT_PASS (pass_ipa_devirt);
>> + NEXT_PASS (pass_ipa_hello_world);
>> NEXT_PASS (pass_ipa_cp);
>> NEXT_PASS (pass_ipa_sra);
>> NEXT_PASS (pass_ipa_cdtor_merge);
>> diff --git a/gcc/tree-pass.h b/gcc/tree-pass.h
>> index a987661..915fc69 100644
>> --- a/gcc/tree-pass.h
>> +++ b/gcc/tree-pass.h
>> @@ -498,6 +498,7 @@ extern ipa_opt_pass_d *make_pass_ipa_fn_summary
>> (gcc::context *ctxt);
>> extern ipa_opt_pass_d *make_pass_ipa_inline (gcc::context *ctxt);
>> extern simple_ipa_opt_pass *make_pass_ipa_free_lang_data (gcc::context
>> *ctxt);
>> extern simple_ipa_opt_pass *make_pass_ipa_free_fn_summary (gcc::context
>> *ctxt);
>> +extern simple_ipa_opt_pass *make_pass_ipa_hello_world (gcc::context
>> *ctxt);
>> extern ipa_opt_pass_d *make_pass_ipa_cp (gcc::context *ctxt);
>> extern ipa_opt_pass_d *make_pass_ipa_sra (gcc::context *ctxt);
>> extern ipa_opt_pass_d *make_pass_ipa_icf (gcc::context *ctxt);
>
