From 861997a9c7088da25ed4dc0bd339060ca063514f Mon Sep 17 00:00:00 2001
From: Robin Dapp <rdapp@ventanamicro.com>
Date: Wed, 24 Jan 2024 17:28:31 +0100
Subject: [PATCH] genopinit: Split init_all_optabs [PR113575].

init_all_optabs initializes > 10000 patterns for riscv targets.  This
leads to pathological situations in dataflow analysis (which can occur
with many adjacent stores).
To alleviate this this patch makes genopinit split the init_all_optabs
function into several init_optabs_xx functions that each initialize 1000
patterns.

With this change insn-opinit.cc's compilation time is reduced from 4+
minutes to 1:30 and memory consumption decreases from 1.2G to 630M.

gcc/ChangeLog:

	PR other/113575

	* genopinit.cc (main): Split init_all_optabs into functions
	of 1000 patterns each.
---
 gcc/genopinit.cc | 43 ++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 38 insertions(+), 5 deletions(-)

diff --git a/gcc/genopinit.cc b/gcc/genopinit.cc
index 88ccafa5b2c..d8682b2a9ad 100644
--- a/gcc/genopinit.cc
+++ b/gcc/genopinit.cc
@@ -367,11 +367,44 @@ main (int argc, const char **argv)
     fprintf (s_file, "  { %#08x, CODE_FOR_%s },\n", p->sort_num, p->name);
   fprintf (s_file, "};\n\n");
 
-  fprintf (s_file, "void\ninit_all_optabs (struct target_optabs *optabs)\n{\n");
-  fprintf (s_file, "  bool *ena = optabs->pat_enable;\n");
-  for (i = 0; patterns.iterate (i, &p); ++i)
-    fprintf (s_file, "  ena[%u] = HAVE_%s;\n", i, p->name);
-  fprintf (s_file, "}\n\n");
+  /* Some targets like riscv have a large number of patterns.  In order to
+     prevent pathological situations in dataflow analysis split the init
+     function into separate ones that initialize 1000 patterns each.  */
+
+  const int patterns_per_function = 1000;
+
+  if (patterns.length () > patterns_per_function)
+    {
+      unsigned num_init_functions
+	= patterns.length () / patterns_per_function + 1;
+      for (i = 0; i < num_init_functions; i++)
+	{
+	  fprintf (s_file, "static void\ninit_optabs_%02d "
+		   "(struct target_optabs *optabs)\n{\n", i);
+	  fprintf (s_file, "  bool *ena = optabs->pat_enable;\n");
+	  unsigned start = i * patterns_per_function;
+	  unsigned end = MIN (patterns.length (),
+			      (i + 1) * patterns_per_function);
+	  for (j = start; j < end; ++j)
+	    fprintf (s_file, "  ena[%u] = HAVE_%s;\n", j, patterns[j].name);
+	  fprintf (s_file, "}\n\n");
+	}
+
+      fprintf (s_file, "void\ninit_all_optabs "
+	       "(struct target_optabs *optabs)\n{\n");
+      for (i = 0; i < num_init_functions; ++i)
+	fprintf (s_file, "  init_optabs_%02d (optabs);\n", i);
+      fprintf (s_file, "}\n\n");
+    }
+  else
+    {
+      fprintf (s_file, "void\ninit_all_optabs "
+	       "(struct target_optabs *optabs)\n{\n");
+      fprintf (s_file, "  bool *ena = optabs->pat_enable;\n");
+      for (i = 0; patterns.iterate (i, &p); ++i)
+	fprintf (s_file, "  ena[%u] = HAVE_%s;\n", i, p->name);
+      fprintf (s_file, "}\n\n");
+    }
 
   fprintf (s_file,
 	   "/* Returns TRUE if the target supports any of the partial vector\n"