[PATCH] New flag for dumping information about constexpr function calls memoization (GCC 5.2.0)

[Andres Tiraboschi <andres dot tiraboschi at tallertechnologies dot com>]

Hi,

This patch adds a flag (-fdump-memoization-hits) in order to dump
information about wich constexpr functions calls are memoized.
This is patch is for gcc-5.2.0.
If OK, please commit it for me since I don't have write access.

patch:

diff --git a/gcc/common.opt b/gcc/common.opt
index 1218a71..bf0c7df 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1168,6 +1168,10 @@ fdump-passes
 Common Var(flag_dump_passes) Init(0)
 Dump optimization passes

+fdump-memoization-hits
+Common Var(flag_dump_memoization_hits) Init(0)
+Dump info about constexpr calls memoized.
+
 fdump-unnumbered
 Common Report Var(flag_dump_unnumbered)
 Suppress output of instruction numbers, line number notes and
addresses in debugging dumps
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index e250726..41ae5b3 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -42,6 +42,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "builtins.h"
 #include "tree-inline.h"
 #include "ubsan.h"
+#include "tree-pretty-print.h"
+#include "dumpfile.h"

 static bool verify_constant (tree, bool, bool *, bool *);
 #define VERIFY_CONSTANT(X)                        \
@@ -1173,6 +1175,14 @@ cx_error_context (void)
   return r;
 }

+static void
+dump_memoization_hit (FILE *file, tree call, int flags)
+{
+  fprintf(file, "Memoized call:\n");
+  print_generic_decl(file, call, flags);
+  fprintf(file, "\n");
+}
+
 /* Subroutine of cxx_eval_constant_expression.
    Evaluate the call expression tree T in the context of OLD_CALL expression
    evaluation.  */
@@ -1338,7 +1348,11 @@ cxx_eval_call_expression (const constexpr_ctx
*ctx, tree t,
       entry->result = result = error_mark_node;
     }
       else
-    result = entry->result;
+    {
+      if (flag_dump_memoization_hits)
+          dump_memoization_hit(stderr, t, 0);
+      result = entry->result;
+    }
     }

   if (!depth_ok)