Fix inter-procedural EAF flags propagation with respect to !binds_to_current_def_p

While proofreading the code for handling EAF flags of !binds_to_current_def_p I
noticed that the interprocedural dataflow actually ignores the flag possibly
introducing wrong code on quite complex interposable functions in non-trivial
recursion cycles (or at ltrans partition boundary).

This patch unifies the flags changes to single place (remove_useless_eaf_flags)
and does extend modref_merge_call_site_flags to do the right thing.

lto-bootstrapped/regtested x86_64-linux.  Plan to commit it today after bit
more testing (firefox/clang build).

gcc/ChangeLog:

	* gimple.c (gimple_call_arg_flags): Use interposable_eaf_flags.
	(gimple_call_retslot_flags): Likewise.
	(gimple_call_static_chain_flags): Likewise.
	* ipa-modref.c (remove_useless_eaf_flags): Do not remove everything for
	NOVOPS.
	(modref_summary::useful_p): Likewise.
	(modref_summary_lto::useful_p): Likewise.
	(analyze_parms): Do not give up on NOVOPS.
	(analyze_function): When dumping report chnages in EAF flags
	between IPA and local pass.
	(modref_merge_call_site_flags): Compute implicit eaf flags
	based on callee ecf_flags and fnspec; if the function does not
	bind to current defs use interposable_eaf_flags.
	(modref_propagate_flags_in_scc): Update.
	* ipa-modref.h (interposable_eaf_flags): New function.

1 files changed, 4 insertions, 30 deletions

diff --git a/gcc/gimple.c b/gcc/gimple.c
index 7a578f5..3d1d3a1 100644
--- a/gcc/gimple.c
+++ b/gcc/gimple.c
@@ -1595,17 +1595,7 @@ gimple_call_arg_flags (const gcall *stmt, unsigned arg)
 
 	  /* We have possibly optimized out load.  Be conservative here.  */
 	  if (!node->binds_to_current_def_p ())
-	    {
-	      if ((modref_flags & EAF_UNUSED) && !(flags & EAF_UNUSED))
-		{
-		  modref_flags &= ~EAF_UNUSED;
-		  modref_flags |= EAF_NOESCAPE;
-		}
-	      if ((modref_flags & EAF_NOREAD) && !(flags & EAF_NOREAD))
-		modref_flags &= ~EAF_NOREAD;
-	      if ((modref_flags & EAF_DIRECT) && !(flags & EAF_DIRECT))
-		modref_flags &= ~EAF_DIRECT;
-	    }
+	    modref_flags = interposable_eaf_flags (modref_flags, flags);
 	  if (dbg_cnt (ipa_mod_ref_pta))
 	    flags |= modref_flags;
 	}
@@ -1633,13 +1623,7 @@ gimple_call_retslot_flags (const gcall *stmt)
 
 	  /* We have possibly optimized out load.  Be conservative here.  */
 	  if (!node->binds_to_current_def_p ())
-	    {
-	      if ((modref_flags & EAF_UNUSED) && !(flags & EAF_UNUSED))
-		{
-		  modref_flags &= ~EAF_UNUSED;
-		  modref_flags |= EAF_NOESCAPE;
-		}
-	    }
+	    modref_flags = interposable_eaf_flags (modref_flags, flags);
 	  if (dbg_cnt (ipa_mod_ref_pta))
 	    flags |= modref_flags;
 	}
@@ -1665,19 +1649,9 @@ gimple_call_static_chain_flags (const gcall *stmt)
 	{
 	  int modref_flags = summary->static_chain_flags;
 
-	  /* We have possibly optimized out load.  Be conservative here.  */
+	  /* ??? Nested functions should always bind to current def.  */
 	  if (!node->binds_to_current_def_p ())
-	    {
-	      if ((modref_flags & EAF_UNUSED) && !(flags & EAF_UNUSED))
-		{
-		  modref_flags &= ~EAF_UNUSED;
-		  modref_flags |= EAF_NOESCAPE;
-		}
-	      if ((modref_flags & EAF_NOREAD) && !(flags & EAF_NOREAD))
-		modref_flags &= ~EAF_NOREAD;
-	      if ((modref_flags & EAF_DIRECT) && !(flags & EAF_DIRECT))
-		modref_flags &= ~EAF_DIRECT;
-	    }
+	    modref_flags = interposable_eaf_flags (modref_flags, flags);
 	  if (dbg_cnt (ipa_mod_ref_pta))
 	    flags |= modref_flags;
 	}