analyzer: add caching to globals with initializers [PR110112]

PR analyzer/110112 notes that -fanalyzer is extremely slow on a source
file with large read-only static arrays, repeatedly building the
same compound_svalue representing the full initializer, and repeatedly
building svalues representing parts of the the full initialiazer.

This patch adds caches for both of these; together they reduce the time
taken by -fanalyzer -O2 on the testcase in the bug for an optimized
build:
  91.2s : no caches (status quo)
  32.4s : cache in decl_region::get_svalue_for_constructor
   3.7s : cache in region::get_initial_value_at_main
   3.1s : both caches (this patch)

gcc/analyzer/ChangeLog:
	PR analyzer/110112
	* region-model.cc (region_model::get_initial_value_for_global):
	Move code to region::calc_initial_value_at_main.
	* region.cc (region::get_initial_value_at_main): New function.
	(region::calc_initial_value_at_main): New function, based on code
	in region_model::get_initial_value_for_global.
	(region::region): Initialize m_cached_init_sval_at_main.
	(decl_region::get_svalue_for_constructor): Add a cache, splitting
	out body to...
	(decl_region::calc_svalue_for_constructor): ...this new function.
	* region.h (region::get_initial_value_at_main): New decl.
	(region::calc_initial_value_at_main): New decl.
	(region::m_cached_init_sval_at_main): New field.
	(decl_region::decl_region): Initialize m_ctor_svalue.
	(decl_region::calc_svalue_for_constructor): New decl.
	(decl_region::m_ctor_svalue): New field.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

1 files changed, 1 insertions, 24 deletions

diff --git a/gcc/analyzer/region-model.cc b/gcc/analyzer/region-model.cc
index fb96cd5..b11cc6c 100644
--- a/gcc/analyzer/region-model.cc
+++ b/gcc/analyzer/region-model.cc
@@ -2355,30 +2355,7 @@ region_model::get_initial_value_for_global (const region *reg) const
      the initial value of REG can be taken from the initialization value
      of the decl.  */
   if (called_from_main_p () || TREE_READONLY (decl))
-    {
-      /* Attempt to get the initializer value for base_reg.  */
-      if (const svalue *base_reg_init
-	    = base_reg->get_svalue_for_initializer (m_mgr))
-	{
-	  if (reg == base_reg)
-	    return base_reg_init;
-	  else
-	    {
-	      /* Get the value for REG within base_reg_init.  */
-	      binding_cluster c (base_reg);
-	      c.bind (m_mgr->get_store_manager (), base_reg, base_reg_init);
-	      const svalue *sval
-		= c.get_any_binding (m_mgr->get_store_manager (), reg);
-	      if (sval)
-		{
-		  if (reg->get_type ())
-		    sval = m_mgr->get_or_create_cast (reg->get_type (),
-						      sval);
-		  return sval;
-		}
-	    }
-	}
-    }
+    return reg->get_initial_value_at_main (m_mgr);
 
   /* Otherwise, return INIT_VAL(REG).  */
   return m_mgr->get_or_create_initial_value (reg);