re PR tree-optimization/38745 (ICE: statement makes a memory store, but has no VDEFS)

2009-01-26  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/38745
	* tree-ssa.c (execute_update_addresses_taken): Do not include
	variables that cannot possibly be a register in not_reg_needs.
	Do not clear TREE_ADDRESSABLE on vars that may not become
	registers.
	* tree-ssa.c (update_alias_info_1): Include those in the set
	of addressable vars.

	* g++.dg/torture/pr38745.C: New testcase.

From-SVN: r143673

gcc/ChangeLog

 2009-01-26  Richard Guenther  <rguenther@suse.de>
 
+	PR tree-optimization/38745
+	* tree-ssa.c (execute_update_addresses_taken): Do not include
+	variables that cannot possibly be a register in not_reg_needs.
+	Do not clear TREE_ADDRESSABLE on vars that may not become
+	registers.
+	* tree-ssa.c (update_alias_info_1): Include those in the set
+	of addressable vars.
+
+2009-01-26  Richard Guenther  <rguenther@suse.de>
+
 	PR middle-end/38851
 	* Makefile.in (tree-ssa-dse.o): Add langhooks.h.
 	* tree-ssa-dse.c: Include langhooks.h

gcc/testsuite/ChangeLog

 2009-01-26  Richard Guenther  <rguenther@suse.de>
 
+	PR tree-optimization/38745
+	* g++.dg/torture/pr38745.C: New testcase.
+
+2009-01-26  Richard Guenther  <rguenther@suse.de>
+
 	PR middle-end/38851
 	* g++.dg/warn/Wuninitialized-1.C: New testcase.
 

gcc/testsuite/g++.dg/torture/pr38745.C

+/* { dg-do compile } */
+
+union u_u16
+{
+  unsigned short v;
+  struct
+    {
+      unsigned char lo8, hi8;
+    } __attribute__ ((__may_alias__)) u;
+} __attribute__ ((__may_alias__));
+union u_u32
+{
+  unsigned int v;
+  struct
+    {
+      u_u16 lo16, hi16;
+    } u;
+} __attribute__ ((__may_alias__));
+union u_u64
+{
+  struct
+    {
+      u_u32 lo32, hi32;
+    } u;
+};
+struct Record
+{
+};
+long long
+UnpackFullKey (Record & rec, const char *&p)
+{
+  long long c64 = 0;
+  (*(u_u16 *) & (*(u_u32 *) & ( *(u_u64*)&c64).u.lo32.v).u.lo16.v).u.hi8 = 1;
+  return c64;
+}
+

gcc/tree-ssa-alias.c

@@ -2483,6 +2483,22 @@ update_alias_info_1 (gimple stmt, struct alias_info *ai)
   if (addr_taken)
     bitmap_ior_into (gimple_addressable_vars (cfun), addr_taken);
 
+  /* If we have a call or an assignment, see if the lhs contains
+     a local decl that requires not to be a gimple register.  */
+  if (gimple_code (stmt) == GIMPLE_ASSIGN
+      || gimple_code (stmt) == GIMPLE_CALL)
+    {
+      tree lhs = gimple_get_lhs (stmt);
+      /* A plain decl does not need it set.  */
+      if (lhs && handled_component_p (lhs))
+	{
+	  tree var = get_base_address (lhs);
+	  if (DECL_P (var)
+	      && is_gimple_reg_type (TREE_TYPE (var)))
+	    bitmap_set_bit (gimple_addressable_vars (cfun), DECL_UID (var));
+	}
+    }
+
   /* Process each operand use.  For pointers, determine whether they
      are dereferenced by the statement, or whether their value
      escapes, etc.  */

gcc/tree-ssa.c

@@ -1731,7 +1731,12 @@ execute_update_addresses_taken (void)
 	  || bitmap_bit_p (addresses_taken, DECL_UID (var)))
 	continue;
 	
-      if (TREE_ADDRESSABLE (var))
+      if (TREE_ADDRESSABLE (var)
+	  /* Do not change TREE_ADDRESSABLE if we need to preserve var as
+	     a non-register.  Otherwise we are confused and forget to
+	     add virtual operands for it.  */
+	  && (!is_gimple_reg_type (TREE_TYPE (var))
+	      || !bitmap_bit_p (not_reg_needs, DECL_UID (var))))
 	{
 	  TREE_ADDRESSABLE (var) = 0;
 	  if (is_gimple_reg (var))