re PR middle-end/38140 (ice for C code with -O2)

	PR middle-end/38140
	* tree-ssa-forwprop.c (forward_propagate_addr_expr_1): If
	propagating x = &a into *x = b, add a cast if not useless
	type conversion or don't optimize if another stmt would be
	needed.

	* gcc.dg/pr38140.c: New test.

From-SVN: r141949

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a916993..ff38275 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2008-11-17  Jakub Jelinek  <jakub@redhat.com>
+
+       PR middle-end/38140
+       * tree-ssa-forwprop.c (forward_propagate_addr_expr_1): If
+       propagating x = &a into *x = b, add a cast if not useless
+       type conversion or don't optimize if another stmt would be
+       needed.
+
 2008-11-17  Uros Bizjak  <ubizjak@gmail.com>
 
        PR middle-end/37908

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 0c0dc1d..00b7cef 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2008-11-17  Jakub Jelinek  <jakub@redhat.com>
+
+       PR middle-end/38140
+       * gcc.dg/pr38140.c: New test.
+
 2008-11-17  Jack Howarth  <howarth@bromo.med.uc.edu>
         
         PR testsuite/38099

diff --git a/gcc/testsuite/gcc.dg/pr38140.c b/gcc/testsuite/gcc.dg/pr38140.c
new file mode 100644 (file)
index 0000000..35f6010
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr38140.c
@@ -0,0 +1,10 @@
+/* PR middle-end/38140 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-strict-aliasing" } */
+
+int foo (void *x)
+{
+  int (*fn) (int);
+  *(void **)&fn = x;
+  return fn (6);
+}

diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c
index 5626b10..333ef82 100644 (file)
--- a/gcc/tree-ssa-forwprop.c
+++ b/gcc/tree-ssa-forwprop.c
@@ -721,13 +721,28 @@ forward_propagate_addr_expr_1 (tree name, tree def_rhs,
       && TREE_OPERAND (lhs, 0) == name
       && may_propagate_address_into_dereference (def_rhs, lhs))
     {
-      *lhsp = unshare_expr (TREE_OPERAND (def_rhs, 0));
-      fold_stmt_inplace (use_stmt);
-      tidy_after_forward_propagate_addr (use_stmt);
+      bool valid = true;
+      if (lhsp == gimple_assign_lhs_ptr (use_stmt)
+         && !useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (def_rhs, 0)),
+                                        TREE_TYPE (rhs))
+         && !CONVERT_EXPR_CODE_P (rhs_code))
+       {
+         if (rhs_code == SSA_NAME)
+           gimple_assign_set_rhs_code (use_stmt, NOP_EXPR);
+         else
+           valid = false;
+       }
+      if (valid)
+       {
+         *lhsp = unshare_expr (TREE_OPERAND (def_rhs, 0));
+         fold_stmt_inplace (use_stmt);
+         tidy_after_forward_propagate_addr (use_stmt);
 
-      /* Continue propagating into the RHS if this was not the only use.  */
-      if (single_use_p)
-       return true;
+         /* Continue propagating into the RHS if this was not the only
+            use.  */
+         if (single_use_p)
+           return true;
+       }
     }
 
   /* Strip away any outer COMPONENT_REF, ARRAY_REF or ADDR_EXPR