[PATCH] Fix -fsanitize=bool -fnon-call-exceptions (PR sanitizer/63913)

[Jakub Jelinek]

Hi!

This patch fixes instrumentation of bool/enum loads if they could
throw.  We want to keep the EH on the load, and push
further statements on the fallthru edge.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2014-11-18  Jakub Jelinek  <ja...@redhat.com>

        PR sanitizer/63913
        * ubsan.c: Include tree-eh.h.
        (instrument_bool_enum_load): Handle loads that can throw.

        * g++.dg/ubsan/pr63913.C: New test.

--- gcc/ubsan.c.jj      2014-11-14 15:11:49.000000000 +0100
+++ gcc/ubsan.c 2014-11-18 09:29:20.409209556 +0100
@@ -67,6 +67,7 @@ along with GCC; see the file COPYING3.
 #include "dfp.h"
 #include "builtins.h"
 #include "tree-object-size.h"
+#include "tree-eh.h"
 
 /* Map from a tree to a VAR_DECL tree.  */
 
@@ -1135,7 +1136,9 @@ instrument_bool_enum_load (gimple_stmt_i
       || TREE_CODE (gimple_assign_lhs (stmt)) != SSA_NAME)
     return;
 
+  bool can_throw = stmt_could_throw_p (stmt);
   location_t loc = gimple_location (stmt);
+  tree lhs = gimple_assign_lhs (stmt);
   tree ptype = build_pointer_type (TREE_TYPE (rhs));
   tree atype = reference_alias_ptr_type (rhs);
   gimple g = gimple_build_assign (make_ssa_name (ptype, NULL),
@@ -1145,9 +1148,24 @@ instrument_bool_enum_load (gimple_stmt_i
   tree mem = build2 (MEM_REF, utype, gimple_assign_lhs (g),
                     build_int_cst (atype, 0));
   tree urhs = make_ssa_name (utype, NULL);
-  g = gimple_build_assign (urhs, mem);
-  gimple_set_location (g, loc);
-  gsi_insert_before (gsi, g, GSI_SAME_STMT);
+  if (can_throw)
+    {
+      gimple_assign_set_lhs (stmt, urhs);
+      g = gimple_build_assign_with_ops (NOP_EXPR, lhs, urhs, NULL_TREE);
+      gimple_set_location (g, loc);
+      edge e = find_fallthru_edge (gimple_bb (stmt)->succs);
+      gsi_insert_on_edge_immediate (e, g);
+      gimple_assign_set_rhs_with_ops (gsi, MEM_REF, mem, NULL_TREE);
+      update_stmt (stmt);
+      *gsi = gsi_for_stmt (g);
+      g = stmt;
+    }
+  else
+    {
+      g = gimple_build_assign (urhs, mem);
+      gimple_set_location (g, loc);
+      gsi_insert_before (gsi, g, GSI_SAME_STMT);
+    }
   minv = fold_convert (utype, minv);
   maxv = fold_convert (utype, maxv);
   if (!integer_zerop (minv))
@@ -1169,8 +1187,11 @@ instrument_bool_enum_load (gimple_stmt_i
   gimple_set_location (g, loc);
   gsi_insert_after (gsi, g, GSI_NEW_STMT);
 
-  gimple_assign_set_rhs_with_ops (&gsi2, NOP_EXPR, urhs, NULL_TREE);
-  update_stmt (stmt);
+  if (!can_throw)
+    {
+      gimple_assign_set_rhs_with_ops (&gsi2, NOP_EXPR, urhs, NULL_TREE);
+      update_stmt (stmt);
+    }
 
   gsi2 = gsi_after_labels (then_bb);
   if (flag_sanitize_undefined_trap_on_error)
--- gcc/testsuite/g++.dg/ubsan/pr63913.C.jj     2014-11-18 09:34:10.603981487 
+0100
+++ gcc/testsuite/g++.dg/ubsan/pr63913.C        2014-11-18 09:33:47.000000000 
+0100
@@ -0,0 +1,12 @@
+// PR sanitizer/63913
+// { dg-do compile }
+// { dg-options "-fsanitize=bool -fnon-call-exceptions" }
+
+struct B { B (); ~B (); };
+
+double
+foo (bool *x)
+{
+  B b;
+  return *x;
+}

        Jakub