experiment with alias

5 files changed, 133 insertions, 0 deletions

diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index aab1dbba57b..98dfaffce25 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -1407,6 +1407,7 @@ 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 1b770bc11a9..3f852ed4cb8 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -3420,4 +3420,8 @@ fipa-ra
 Common Report Var(flag_ipa_ra) Optimization
 Use caller save register across calls if possible.
 
+fipa-hello-world
+Common Report Var(flag_ipa_hello_world) Optimization
+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 00000000000..00e276a4bd7
--- /dev/null
+++ b/gcc/ipa-hello-world.c
@@ -0,0 +1,126 @@
+#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"
+#include "tree-ssa-alias.h"
+#include "tree-ssanames.h"
+#include "gimple.h"
+#include "cfg.h"
+#include "gimple-iterator.h"
+#include "gimple-ssa.h"
+
+void inline
+log(const char* const fmt, ...)
+{
+  if (!dump_file) return;
+  
+  va_list args;
+  va_start(args, fmt);
+  vfprintf(dump_file, fmt, args);
+  va_end(args);
+}
+
+static void
+alias_experiment_gimple_body(const cgraph_node *cnode)
+{
+  gcc_assert(cnode);
+
+  function *func = DECL_STRUCT_FUNCTION(cnode->decl);
+
+  // We are looking first into SSA becaues of
+  // this documentation... 
+  // Points-to and escape analysis. 
+  // Points-to analysis builds a set of constraints from the GIMPLE SSA IL 
+  // representing all pointer operations and facts we do or do not know 
+  // about pointers. Solving this set of constraints yields a conservatively 
+  // correct solution for each pointer variable in the program (though we are 
+  // only interested in SSA name pointers) as to what it may possibly point to.
+  // https://gcc.gnu.org/onlinedocs/gccint/Alias-analysis.html
+  
+  size_t j = 0;
+  tree var_decl = NULL;
+  FOR_EACH_LOCAL_DECL(func, j, var_decl)
+  {
+    const_tree identifier_node = DECL_NAME(var_decl);
+    if (!identifier_node) continue;
+    const char* const identifier_pointer = IDENTIFIER_POINTER(identifier_node);
+    log("var_decl = %s\n", identifier_pointer);
+    if (POINTER_TYPE_P(TREE_TYPE(var_decl))) break;
+  }
+
+  size_t i = 0;
+  tree ssa_name = NULL;
+  push_cfun(func);
+  FOR_EACH_SSA_NAME(i, ssa_name, cfun)
+  {
+    struct ptr_info_def *pi = SSA_NAME_PTR_INFO(ssa_name);
+    if (!pi) continue;
+    log("i have a pi");
+    pt_solution_includes(&pi->pt, var_decl);
+  }
+  pop_cfun();
+
+
+}
+
+static unsigned int
+iphw_execute()
+{
+  cgraph_node *node = NULL;
+  FOR_EACH_FUNCTION_WITH_GIMPLE_BODY(node)
+  {
+    alias_experiment_gimple_body (node);
+  }
+  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,
+  TODO_rebuild_alias,
+  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_hello_world; }
+  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 92cbe587a8a..442e1e7b0e1 100644
--- a/gcc/passes.def
+++ b/gcc/passes.def
@@ -149,6 +149,7 @@ 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 576b3f67434..30782a91c30 100644
--- a/gcc/tree-pass.h
+++ b/gcc/tree-pass.h
@@ -502,6 +502,7 @@ 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);