2015-04-16 Richard Biener <rguenther@suse.de>

	* tree-ssa-ccp.c (likely_value): See if we have operands that
	are marked as never simulate again and return CONSTANT in this
	case.
	* tree-ssa-propagate.c (simulate_stmt): Mark stmts that do
	not have any operands that will be simulated again as
	not being simulated again.

	* gcc.dg/tree-ssa/ssa-ccp-36.c: New testcase.
	* gcc.dg/tree-ssa/pr37508.c: Adjust.
	* gfortran.dg/reassoc_6.f: Remove XFAIL.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@222141 138bc75d-0d04-0410-961f-82ee72b054a4

7 files changed, 82 insertions, 6 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6571c1f1558..a3a2016c990 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2015-04-16  Richard Biener  <rguenther@suse.de>
+
+	* tree-ssa-ccp.c (likely_value): See if we have operands that
+	are marked as never simulate again and return CONSTANT in this
+	case.
+	* tree-ssa-propagate.c (simulate_stmt): Mark stmts that do
+	not have any operands that will be simulated again as
+	not being simulated again.
+
 2015-04-15  Uros Bizjak  <ubizjak@gmail.com>
 
 	* config/i386/i386.md (*cmpi<FPCMP:unord><MODEF:mode>_mixed):
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 0912b4b571b..2fd765cb110 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2015-04-16  Richard Biener  <rguenther@suse.de>
+
+	* gcc.dg/tree-ssa/ssa-ccp-36.c: New testcase.
+	* gcc.dg/tree-ssa/pr37508.c: Adjust.
+	* gfortran.dg/reassoc_6.f: Remove XFAIL.
+
 2015-04-15  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* g++.dg/cpp0x/alias-decl-22.C: Adjust for error + inform change.
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr37508.c b/gcc/testsuite/gcc.dg/tree-ssa/pr37508.c
index aea35cc04ed..19b54fe16e9 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr37508.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr37508.c
@@ -21,7 +21,7 @@ int test2 (struct foo2 *x)
 {
   if (x->i == 0)
     return 1;
-  else if (x->i == -1)
+  else if (x->i == -1) /* This test is already folded to false by ccp1.  */
     return 1;
   return 0;
 }
@@ -44,5 +44,5 @@ int test4 (struct foo2 *x)
   return 0;
 }
 
-/* { dg-final { scan-tree-dump-times "Folding" 3 "vrp1" } } */
+/* { dg-final { scan-tree-dump-times "Folding" 2 "vrp1" } } */
 /* { dg-final { cleanup-tree-dump "vrp1" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-36.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-36.c
new file mode 100644
index 00000000000..bd72fbd6697
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-36.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-ccp1" } */
+
+int foo (int i, int j)
+{
+  int x = 1;
+  int y = i + x;
+  int z = y - i;
+  if (z == 1)
+    return 1;
+  return 2;
+}
+
+/* { dg-final { scan-tree-dump "return 1;" "ccp1" } } */
+/* { dg-final { cleanup-tree-dump "ccp1" } } */
diff --git a/gcc/testsuite/gfortran.dg/reassoc_6.f b/gcc/testsuite/gfortran.dg/reassoc_6.f
index 97a5de8a748..cbc36f5675b 100644
--- a/gcc/testsuite/gfortran.dg/reassoc_6.f
+++ b/gcc/testsuite/gfortran.dg/reassoc_6.f
@@ -16,7 +16,5 @@
         return
         end
 ! Verify that offset of the first element is simplified
-! While we understand to combine x + ~x IVOPTs now messes things
-! up by hiding that operation in casts to unsigned.
-! { dg-final { scan-tree-dump-not "~" "optimized" { xfail *-*-* } } }
+! { dg-final { scan-tree-dump-not "~" "optimized" } }
 ! { dg-final { cleanup-tree-dump "optimized" } }
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index eeae4bfcd35..996296b4e36 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -646,6 +646,7 @@ static ccp_lattice_t
 likely_value (gimple stmt)
 {
   bool has_constant_operand, has_undefined_operand, all_undefined_operands;
+  bool has_nsa_operand;
   tree use;
   ssa_op_iter iter;
   unsigned i;
@@ -668,6 +669,7 @@ likely_value (gimple stmt)
   has_constant_operand = false;
   has_undefined_operand = false;
   all_undefined_operands = true;
+  has_nsa_operand = false;
   FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
     {
       ccp_prop_value_t *val = get_value (use);
@@ -679,6 +681,10 @@ likely_value (gimple stmt)
 
       if (val->lattice_val == CONSTANT)
 	has_constant_operand = true;
+
+      if (SSA_NAME_IS_DEFAULT_DEF (use)
+	  || !prop_simulate_again_p (SSA_NAME_DEF_STMT (use)))
+	has_nsa_operand = true;
     }
 
   /* There may be constants in regular rhs operands.  For calls we
@@ -751,8 +757,10 @@ likely_value (gimple stmt)
 
   /* We do not consider virtual operands here -- load from read-only
      memory may have only VARYING virtual operands, but still be
-     constant.  */
+     constant.  Also we can combine the stmt with definitions from
+     operands whose definitions are not simulated again.  */
   if (has_constant_operand
+      || has_nsa_operand
       || gimple_references_memory_p (stmt))
     return CONSTANT;
 
diff --git a/gcc/tree-ssa-propagate.c b/gcc/tree-ssa-propagate.c
index c3f9d3e1cda..e23da7094a4 100644
--- a/gcc/tree-ssa-propagate.c
+++ b/gcc/tree-ssa-propagate.c
@@ -366,6 +366,7 @@ simulate_stmt (gimple stmt)
 	  FOR_EACH_EDGE (e, ei, bb->succs)
 	    add_control_edge (e);
 	}
+      return;
     }
   else if (val == SSA_PROP_INTERESTING)
     {
@@ -379,6 +380,45 @@ simulate_stmt (gimple stmt)
       if (taken_edge)
 	add_control_edge (taken_edge);
     }
+
+  /* If there are no SSA uses on the stmt whose defs are simulated
+     again then this stmt will be never visited again.  */
+  bool has_simulate_again_uses = false;
+  use_operand_p use_p;
+  ssa_op_iter iter;
+  if (gimple_code  (stmt) == GIMPLE_PHI)
+    {
+      edge_iterator ei;
+      edge e;
+      tree arg;
+      FOR_EACH_EDGE (e, ei, gimple_bb (stmt)->preds)
+	if (!(e->flags & EDGE_EXECUTABLE)
+	    || ((arg = PHI_ARG_DEF_FROM_EDGE (stmt, e))
+		&& TREE_CODE (arg) == SSA_NAME
+		&& !SSA_NAME_IS_DEFAULT_DEF (arg)
+		&& prop_simulate_again_p (SSA_NAME_DEF_STMT (arg))))
+	  {
+	    has_simulate_again_uses = true;
+	    break;
+	  }
+    }
+  else
+    FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
+      {
+	gimple def_stmt = SSA_NAME_DEF_STMT (USE_FROM_PTR (use_p));
+	if (!gimple_nop_p (def_stmt)
+	    && prop_simulate_again_p (def_stmt))
+	  {
+	    has_simulate_again_uses = true;
+	    break;
+	  }
+      }
+  if (!has_simulate_again_uses)
+    {
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, "marking stmt to be not simulated again\n");
+      prop_set_simulate_again (stmt, false);
+    }
 }
 
 /* Process an SSA edge worklist.  WORKLIST is the SSA edge worklist to