From: Eric Botcazou <ebotcazou@adacore.com>
Date: Thu, 6 Nov 2014 20:13:18 +0000 (+0000)
Subject: * tree-cfgcleanup.c (fixup_noreturn_call): Do not perform DCE here.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=2f1b0141be5581d0795c3369dcb9eaf27abe35f7;p=gcc.git

* tree-cfgcleanup.c (fixup_noreturn_call): Do not perform DCE here.

From-SVN: r217201
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d59a3604392..57976f55647 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2014-11-06  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* tree-cfgcleanup.c (fixup_noreturn_call): Do not perform DCE here.
+
 2014-11-06  DJ Delorie  <dj@redhat.com>
 
 	* config/m32c/cond.md (movqicc_<code>_<mode>): Remove mode of
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 003a044eec6..bc50a71ab2e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2014-11-06  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gnat.dg/opt43.adb: New test.
+
 2014-11-06  Marek Polacek  <polacek@redhat.com>
 
 	* c-c++-common/ubsan/align-2.c: Add dg-output.
diff --git a/gcc/testsuite/gnat.dg/opt43.adb b/gcc/testsuite/gnat.dg/opt43.adb
new file mode 100644
index 00000000000..35b407c0afd
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/opt43.adb
@@ -0,0 +1,21 @@
+-- { dg-do compile }
+-- { dg-options "-O -gnatws" }
+
+procedure Opt43 is
+
+  function Func return Integer is
+  begin
+    if False then
+       return 0;
+    end if;
+  end;
+
+begin
+
+  if Func = Func then
+    raise Program_Error;
+  end if;
+
+exception
+  when Program_Error => null;
+end;
diff --git a/gcc/tree-cfgcleanup.c b/gcc/tree-cfgcleanup.c
index ec2f55a95b6..fa383acb4f2 100644
--- a/gcc/tree-cfgcleanup.c
+++ b/gcc/tree-cfgcleanup.c
@@ -568,7 +568,6 @@ bool
 fixup_noreturn_call (gimple stmt)
 {
   basic_block bb = gimple_bb (stmt);
-  bool changed = false;
 
   if (gimple_call_builtin_p (stmt, BUILT_IN_RETURN))
     return false;
@@ -590,46 +589,25 @@ fixup_noreturn_call (gimple stmt)
 	split_block (bb, stmt);
     }
 
-  changed |= remove_fallthru_edge (bb->succs);
-
-  /* If there is LHS, remove it.  */
-  if (gimple_call_lhs (stmt))
+  /* If there is an LHS, remove it.  */
+  tree lhs = gimple_call_lhs (stmt);
+  if (lhs)
     {
-      tree op = gimple_call_lhs (stmt);
       gimple_call_set_lhs (stmt, NULL_TREE);
 
-      /* We need to remove SSA name to avoid checking errors.
-	 All uses are dominated by the noreturn and thus will
-	 be removed afterwards.
-	 We proactively remove affected non-PHI statements to avoid
-	 fixup_cfg from trying to update them and crashing.  */
-      if (TREE_CODE (op) == SSA_NAME)
+      /* We need to fix up the SSA name to avoid checking errors.  */
+      if (TREE_CODE (lhs) == SSA_NAME)
 	{
-	  use_operand_p use_p;
-          imm_use_iterator iter;
-	  gimple use_stmt;
-	  bitmap_iterator bi;
-	  unsigned int bb_index;
-
-	  bitmap blocks = BITMAP_ALLOC (NULL);
-
-          FOR_EACH_IMM_USE_STMT (use_stmt, iter, op)
-	    {
-	      if (gimple_code (use_stmt) != GIMPLE_PHI)
-	        bitmap_set_bit (blocks, gimple_bb (use_stmt)->index);
-	      else
-		FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
-		  SET_USE (use_p, error_mark_node);
-	    }
-	  EXECUTE_IF_SET_IN_BITMAP (blocks, 0, bb_index, bi)
-	    delete_basic_block (BASIC_BLOCK_FOR_FN (cfun, bb_index));
-	  BITMAP_FREE (blocks);
-	  release_ssa_name (op);
+	  tree new_var = create_tmp_reg (TREE_TYPE (lhs), NULL);
+	  SET_SSA_NAME_VAR_OR_IDENTIFIER (lhs, new_var);
+	  SSA_NAME_DEF_STMT (lhs) = gimple_build_nop ();
+	  set_ssa_default_def (cfun, new_var, lhs);
 	}
+
       update_stmt (stmt);
-      changed = true;
     }
-  return changed;
+
+  return remove_fallthru_edge (bb->succs);
 }