Enable chained function calls in C++ expressions.

gdb/ChangeLog:

	* eval.c: Include gdbthread.h.
	(evaluate_subexp): Enable thread stack temporaries before
	evaluating a complete expression and clean them up after the
	evaluation is complete.
	* gdbthread.h: Include common/vec.h.
	(value_ptr): New typedef.
	(VEC (value_ptr)): New vector type.
	(value_vec): New typedef.
	(struct thread_info): Add new fields stack_temporaries_enabled
	and stack_temporaries.
	(enable_thread_stack_temporaries)
	(thread_stack_temporaries_enabled_p, push_thread_stack_temporary)
	(get_last_thread_stack_temporary)
	(value_in_thread_stack_temporaries): Declare.
	* gdbtypes.c (class_or_union_p): New function.
	* gdbtypes.h (class_or_union_p): Declare.
	* infcall.c (call_function_by_hand): Store return values of class
	type as	temporaries on stack.
	* thread.c (enable_thread_stack_temporaries): New function.
	(thread_stack_temporaries_enabled_p, push_thread_stack_temporary)
	(get_last_thread_stack_temporary): Likewise.
	(value_in_thread_stack_temporaries): Likewise.
	* value.c (value_force_lval): New function.
	* value.h (value_force_lval): Declare.

gdb/testsuite/ChangeLog:

	* gdb.cp/chained-calls.cc: New file.
	* gdb.cp/chained-calls.exp: New file.
	* gdb.cp/smartp.exp: Remove KFAIL for "p c2->inta".

gdb/ChangeLog

@@ -1,3 +1,30 @@
+2014-11-28  Siva Chandra Reddy  <sivachandra@google.com>
+
+	* eval.c: Include gdbthread.h.
+	(evaluate_subexp): Enable thread stack temporaries before
+	evaluating a complete expression and clean them up after the
+	evaluation is complete.
+	* gdbthread.h: Include common/vec.h.
+	(value_ptr): New typedef.
+	(VEC (value_ptr)): New vector type.
+	(value_vec): New typedef.
+	(struct thread_info): Add new fields stack_temporaries_enabled
+	and stack_temporaries.
+	(enable_thread_stack_temporaries)
+	(thread_stack_temporaries_enabled_p, push_thread_stack_temporary)
+	(get_last_thread_stack_temporary)
+	(value_in_thread_stack_temporaries): Declare.
+	* gdbtypes.c (class_or_union_p): New function.
+	* gdbtypes.h (class_or_union_p): Declare.
+	* infcall.c (call_function_by_hand): Store return values of class
+	type as	temporaries on stack.
+	* thread.c (enable_thread_stack_temporaries): New function.
+	(thread_stack_temporaries_enabled_p, push_thread_stack_temporary)
+	(get_last_thread_stack_temporary): Likewise.
+	(value_in_thread_stack_temporaries): Likewise.
+	* value.c (value_force_lval): New function.
+	* value.h (value_force_lval): Declare.
+
 2014-11-28  Pierre Muller  <muller@sourceware.org>
 
 	Pushed by Joel Brobecker  <brobecker@adacore.com>.

gdb/eval.c

@@ -24,6 +24,7 @@
 #include "expression.h"
 #include "target.h"
 #include "frame.h"
+#include "gdbthread.h"
 #include "language.h"		/* For CAST_IS_CONVERSION.  */
 #include "f-lang.h"		/* For array bound stuff.  */
 #include "cp-abi.h"
@@ -63,8 +64,28 @@ struct value *
 evaluate_subexp (struct type *expect_type, struct expression *exp,
 		 int *pos, enum noside noside)
 {
-  return (*exp->language_defn->la_exp_desc->evaluate_exp) 
+  struct cleanup *cleanups;
+  struct value *retval;
+  int cleanup_temps = 0;
+
+  if (*pos == 0 && target_has_execution
+      && exp->language_defn->la_language == language_cplus)
+    {
+      cleanups = enable_thread_stack_temporaries (inferior_ptid);
+      cleanup_temps = 1;
+    }
+
+  retval = (*exp->language_defn->la_exp_desc->evaluate_exp)
     (expect_type, exp, pos, noside);
+
+  if (cleanup_temps)
+    {
+      if (value_in_thread_stack_temporaries (retval, inferior_ptid))
+	retval = value_non_lval (retval);
+      do_cleanups (cleanups);
+    }
+
+  return retval;
 }
 
 /* Parse the string EXP as a C expression, evaluate it,

gdb/gdbthread.h

@@ -28,6 +28,7 @@ struct symtab;
 #include "ui-out.h"
 #include "inferior.h"
 #include "btrace.h"
+#include "common/vec.h"
 
 /* Frontend view of the thread state.  Possible extensions: stepping,
    finishing, until(ling),...  */
@@ -152,6 +153,10 @@ struct thread_suspend_state
   enum gdb_signal stop_signal;
 };
 
+typedef struct value *value_ptr;
+DEF_VEC_P (value_ptr);
+typedef VEC (value_ptr) value_vec;
+
 struct thread_info
 {
   struct thread_info *next;
@@ -264,6 +269,14 @@ struct thread_info
 
   /* Branch trace information for this thread.  */
   struct btrace_thread_info btrace;
+
+  /* Flag which indicates that the stack temporaries should be stored while
+     evaluating expressions.  */
+  int stack_temporaries_enabled;
+
+  /* Values that are stored as temporaries on stack while evaluating
+     expressions.  */
+  value_vec *stack_temporaries;
 };
 
 /* Create an empty thread list, or empty the existing one.  */
@@ -465,6 +478,16 @@ extern void prune_threads (void);
 
 int pc_in_thread_step_range (CORE_ADDR pc, struct thread_info *thread);
 
+extern struct cleanup *enable_thread_stack_temporaries (ptid_t ptid);
+
+extern int thread_stack_temporaries_enabled_p (ptid_t ptid);
+
+extern void push_thread_stack_temporary (ptid_t ptid, struct value *v);
+
+extern struct value *get_last_thread_stack_temporary (ptid_t);
+
+extern int value_in_thread_stack_temporaries (struct value *, ptid_t);
+
 extern struct thread_info *thread_list;
 
 #endif /* GDBTHREAD_H */

gdb/gdbtypes.c

@@ -2508,6 +2508,15 @@ is_scalar_type_recursive (struct type *t)
   return 0;
 }
 
+/* Return true is T is a class or a union.  False otherwise.  */
+
+int
+class_or_union_p (const struct type *t)
+{
+  return (TYPE_CODE (t) == TYPE_CODE_STRUCT
+          || TYPE_CODE (t) == TYPE_CODE_UNION);
+}
+
 /* A helper function which returns true if types A and B represent the
    "same" class type.  This is true if the types have the same main
    type, or the same name.  */

gdb/gdbtypes.h

@@ -1823,6 +1823,8 @@ extern int is_integral_type (struct type *);
 
 extern int is_scalar_type_recursive (struct type *);
 
+extern int class_or_union_p (const struct type *);
+
 extern void maintenance_print_type (char *, int);
 
 extern htab_t create_copied_types_hash (struct objfile *objfile);

gdb/infcall.c

@@ -495,6 +495,7 @@ call_function_by_hand (struct value *function, int nargs, struct value **args)
   ptid_t call_thread_ptid;
   struct gdb_exception e;
   char name_buf[RAW_FUNCTION_ADDRESS_SIZE];
+  int stack_temporaries = thread_stack_temporaries_enabled_p (inferior_ptid);
 
   if (TYPE_CODE (ftype) == TYPE_CODE_PTR)
     ftype = check_typedef (TYPE_TARGET_TYPE (ftype));
@@ -593,6 +594,33 @@ call_function_by_hand (struct value *function, int nargs, struct value **args)
          If the ABI specifies a "Red Zone" (see the doco) the code
          below will quietly trash it.  */
       sp = old_sp;
+
+    /* Skip over the stack temporaries that might have been generated during
+       the evaluation of an expression.  */
+    if (stack_temporaries)
+      {
+	struct value *lastval;
+
+	lastval = get_last_thread_stack_temporary (inferior_ptid);
+        if (lastval != NULL)
+	  {
+	    CORE_ADDR lastval_addr = value_address (lastval);
+
+	    if (gdbarch_inner_than (gdbarch, 1, 2))
+	      {
+		gdb_assert (sp >= lastval_addr);
+		sp = lastval_addr;
+	      }
+	    else
+	      {
+		gdb_assert (sp <= lastval_addr);
+		sp = lastval_addr + TYPE_LENGTH (value_type (lastval));
+	      }
+
+	    if (gdbarch_frame_align_p (gdbarch))
+	      sp = gdbarch_frame_align (gdbarch, sp);
+	  }
+      }
   }
 
   funaddr = find_function_addr (function, &values_type);
@@ -719,9 +747,21 @@ call_function_by_hand (struct value *function, int nargs, struct value **args)
 
   /* Reserve space for the return structure to be written on the
      stack, if necessary.  Make certain that the value is correctly
-     aligned.  */
+     aligned.
 
-  if (struct_return || hidden_first_param_p)
+     While evaluating expressions, we reserve space on the stack for
+     return values of class type even if the language ABI and the target
+     ABI do not require that the return value be passed as a hidden first
+     argument.  This is because we want to store the return value as an
+     on-stack temporary while the expression is being evaluated.  This
+     enables us to have chained function calls in expressions.
+
+     Keeping the return values as on-stack temporaries while the expression
+     is being evaluated is OK because the thread is stopped until the
+     expression is completely evaluated.  */
+
+  if (struct_return || hidden_first_param_p
+      || (stack_temporaries && class_or_union_p (values_type)))
     {
       if (gdbarch_inner_than (gdbarch, 1, 2))
 	{
@@ -1059,31 +1099,40 @@ When the function is done executing, GDB will silently stop."),
        At this stage, leave the RETBUF alone.  */
     restore_infcall_control_state (inf_status);
 
-    /* Figure out the value returned by the function.  */
-    retval = allocate_value (values_type);
-
-    if (hidden_first_param_p)
-      read_value_memory (retval, 0, 1, struct_addr,
-			 value_contents_raw (retval),
-			 TYPE_LENGTH (values_type));
-    else if (TYPE_CODE (target_values_type) != TYPE_CODE_VOID)
+    if (TYPE_CODE (values_type) == TYPE_CODE_VOID)
+      retval = allocate_value (values_type);
+    else if (struct_return || hidden_first_param_p)
       {
-	/* If the function returns void, don't bother fetching the
-	   return value.  */
-	switch (gdbarch_return_value (gdbarch, function, target_values_type,
-				      NULL, NULL, NULL))
+	if (stack_temporaries)
 	  {
-	  case RETURN_VALUE_REGISTER_CONVENTION:
-	  case RETURN_VALUE_ABI_RETURNS_ADDRESS:
-	  case RETURN_VALUE_ABI_PRESERVES_ADDRESS:
-	    gdbarch_return_value (gdbarch, function, values_type,
-				  retbuf, value_contents_raw (retval), NULL);
-	    break;
-	  case RETURN_VALUE_STRUCT_CONVENTION:
+	    retval = value_from_contents_and_address (values_type, NULL,
+						      struct_addr);
+	    push_thread_stack_temporary (inferior_ptid, retval);
+	  }
+	else
+	  {
+	    retval = allocate_value (values_type);
 	    read_value_memory (retval, 0, 1, struct_addr,
 			       value_contents_raw (retval),
 			       TYPE_LENGTH (values_type));
-	    break;
+	  }
+      }
+    else
+      {
+	retval = allocate_value (values_type);
+	gdbarch_return_value (gdbarch, function, values_type,
+			      retbuf, value_contents_raw (retval), NULL);
+	if (stack_temporaries && class_or_union_p (values_type))
+	  {
+	    /* Values of class type returned in registers are copied onto
+	       the stack and their lval_type set to lval_memory.  This is
+	       required because further evaluation of the expression
+	       could potentially invoke methods on the return value
+	       requiring GDB to evaluate the "this" pointer.  To evaluate
+	       the this pointer, GDB needs the memory address of the
+	       value.  */
+	    value_force_lval (retval, struct_addr);
+	    push_thread_stack_temporary (inferior_ptid, retval);
 	  }
       }
 

gdb/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2014-11-28  Siva Chandra Reddy  <sivachandra@google.com>
+
+	* gdb.cp/chained-calls.cc: New file.
+	* gdb.cp/chained-calls.exp: New file.
+	* gdb.cp/smartp.exp: Remove KFAIL for "p c2->inta".
+
 2014-11-28  Simon Marchi  <simon.marchi@ericsson.com>
 
 	* gdb.ada/py_range.exp: Add parentheses to python calls to print.

gdb/testsuite/gdb.cp/chained-calls.cc

@@ -0,0 +1,203 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2014 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+class S
+{
+public:
+  S () { }
+  S (S &obj);
+
+  S operator+ (const S &s);
+
+  int a;
+};
+
+S::S (S &obj)
+{
+  a = obj.a;
+}
+
+S
+S::operator+ (const S &s)
+{
+  S res;
+
+  res.a = a + s.a;
+
+  return res;
+}
+
+S
+f (int i)
+{
+  S s;
+
+  s.a = i;
+
+  return s;
+}
+
+int
+g (const S &s)
+{
+  return s.a;
+}
+
+class A
+{
+public:
+  A operator+ (const A &);
+  int a;
+};
+
+A
+A::operator+ (const A &obj)
+{
+  A n;
+
+  n.a = a + obj.a;
+
+  return n;
+}
+
+A
+p ()
+{
+  A a;
+  a.a = 12345678;
+  return a;
+}
+
+A
+r ()
+{
+  A a;
+  a.a = 10000000;
+  return a;
+}
+
+A
+q (const A &a)
+{
+  return a;
+}
+
+class B
+{
+public:
+  int b[1024];
+};
+
+B
+makeb ()
+{
+  B b;
+  int i;
+
+  for (i = 0; i < 1024; i++)
+    b.b[i] = i;
+
+  return b;
+}
+
+int
+getb (const B &b, int i)
+{
+  return b.b[i];
+}
+
+class C
+{
+public:
+  C ();
+  ~C ();
+
+  A operator* ();
+
+  A *a_ptr;
+};
+
+C::C ()
+{
+  a_ptr = new A;
+  a_ptr->a = 5678;
+}
+
+C::~C ()
+{
+  delete a_ptr;
+}
+
+A
+C::operator* ()
+{
+  return *a_ptr;
+}
+
+#define TYPE_INDEX 1
+
+enum type
+{
+  INT,
+  CHAR
+};
+
+union U
+{
+public:
+  U (type t);
+  type get_type ();
+
+  int a;
+  char c;
+  type tp[2];
+};
+
+U::U (type t)
+{
+  tp[TYPE_INDEX] = t;
+}
+
+U
+make_int ()
+{
+  return U (INT);
+}
+
+U
+make_char ()
+{
+  return U (CHAR);
+}
+
+type
+U::get_type ()
+{
+  return tp[TYPE_INDEX];
+}
+
+int
+main ()
+{
+  int i = g(f(0));
+  A a = q(p() + r());
+
+  B b = makeb ();
+  C c;
+
+  return i + getb(b, 0);  /* Break here  */
+}

gdb/testsuite/gdb.cp/chained-calls.exp

@@ -0,0 +1,44 @@
+# Copyright 2014 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file is part of the gdb testsuite
+
+if {[skip_cplus_tests]} { continue }
+
+standard_testfile .cc
+
+if {[prepare_for_testing $testfile.exp $testfile $srcfile {debug c++}]} {
+    return -1
+}
+
+if {![runto_main]} {
+    return -1
+}
+
+gdb_breakpoint [gdb_get_line_number "Break here"]
+gdb_continue_to_breakpoint "Break here"
+
+gdb_test "p g(f(12345))" ".* = 12345" "g(f())"
+gdb_test "p q(p())" ".* = {a = 12345678}" "q(p())"
+gdb_test "p p() + r()" ".* = {a = 22345678}" "p() + r()"
+gdb_test "p q(p() + r())" ".* = {a = 22345678}" "q(p() + r())"
+gdb_test "p g(f(6700) + f(89))" ".* = 6789" "g(f() + f())"
+gdb_test "p g(f(g(f(300) + f(40))) + f(5))" ".* = 345" \
+    "g(f(g(f() + f())) + f())"
+gdb_test "p getb(makeb(), 789)" ".* = 789" "getb(makeb(), ...)"
+gdb_test "p *c" ".* = {a = 5678}" "*c"
+gdb_test "p *c + *c" ".* = {a = 11356}" "*c + *c"
+gdb_test "P q(*c + *c)" ".* = {a = 11356}" "q(*c + *c)"
+gdb_test "p make_int().get_type ()" ".* = INT" "make_int().get_type ()"

gdb/testsuite/gdb.cp/smartp.exp

@@ -72,6 +72,5 @@ gdb_test "p b->foo()"         "= 66"
 gdb_test "p c->foo()"         "= 66"
 gdb_test "p c->inta"          "= 77"
 
-setup_kfail "gdb/11606" "*-*-*"
 gdb_test "p c2->inta"          "= 77"
 

gdb/thread.c

@@ -636,6 +636,108 @@ prune_threads (void)
     }
 }
 
+/* Disable storing stack temporaries for the thread whose id is
+   stored in DATA.  */
+
+static void
+disable_thread_stack_temporaries (void *data)
+{
+  ptid_t *pd = data;
+  struct thread_info *tp = find_thread_ptid (*pd);
+
+  if (tp != NULL)
+    {
+      tp->stack_temporaries_enabled = 0;
+      VEC_free (value_ptr, tp->stack_temporaries);
+    }
+
+  xfree (pd);
+}
+
+/* Enable storing stack temporaries for thread with id PTID and return a
+   cleanup which can disable and clear the stack temporaries.  */
+
+struct cleanup *
+enable_thread_stack_temporaries (ptid_t ptid)
+{
+  struct thread_info *tp = find_thread_ptid (ptid);
+  ptid_t  *data;
+  struct cleanup *c;
+
+  gdb_assert (tp != NULL);
+
+  tp->stack_temporaries_enabled = 1;
+  tp->stack_temporaries = NULL;
+  data = (ptid_t *) xmalloc (sizeof (ptid_t));
+  *data = ptid;
+  c = make_cleanup (disable_thread_stack_temporaries, data);
+
+  return c;
+}
+
+/* Return non-zero value if stack temporaies are enabled for the thread
+   with id PTID.  */
+
+int
+thread_stack_temporaries_enabled_p (ptid_t ptid)
+{
+  struct thread_info *tp = find_thread_ptid (ptid);
+
+  if (tp == NULL)
+    return 0;
+  else
+    return tp->stack_temporaries_enabled;
+}
+
+/* Push V on to the stack temporaries of the thread with id PTID.  */
+
+void
+push_thread_stack_temporary (ptid_t ptid, struct value *v)
+{
+  struct thread_info *tp = find_thread_ptid (ptid);
+
+  gdb_assert (tp != NULL && tp->stack_temporaries_enabled);
+  VEC_safe_push (value_ptr, tp->stack_temporaries, v);
+}
+
+/* Return 1 if VAL is among the stack temporaries of the thread
+   with id PTID.  Return 0 otherwise.  */
+
+int
+value_in_thread_stack_temporaries (struct value *val, ptid_t ptid)
+{
+  struct thread_info *tp = find_thread_ptid (ptid);
+
+  gdb_assert (tp != NULL && tp->stack_temporaries_enabled);
+  if (!VEC_empty (value_ptr, tp->stack_temporaries))
+    {
+      struct value *v;
+      int i;
+
+      for (i = 0; VEC_iterate (value_ptr, tp->stack_temporaries, i, v); i++)
+	if (v == val)
+	  return 1;
+    }
+
+  return 0;
+}
+
+/* Return the last of the stack temporaries for thread with id PTID.
+   Return NULL if there are no stack temporaries for the thread.  */
+
+struct value *
+get_last_thread_stack_temporary (ptid_t ptid)
+{
+  struct value *lastval = NULL;
+  struct thread_info *tp = find_thread_ptid (ptid);
+
+  gdb_assert (tp != NULL);
+  if (!VEC_empty (value_ptr, tp->stack_temporaries))
+    lastval = VEC_last (value_ptr, tp->stack_temporaries);
+
+  return lastval;
+}
+
 void
 thread_change_ptid (ptid_t old_ptid, ptid_t new_ptid)
 {

gdb/value.c

@@ -1724,6 +1724,18 @@ value_non_lval (struct value *arg)
    return arg;
 }
 
+/* Write contents of V at ADDR and set its lval type to be LVAL_MEMORY.  */
+
+void
+value_force_lval (struct value *v, CORE_ADDR addr)
+{
+  gdb_assert (VALUE_LVAL (v) == not_lval);
+
+  write_memory (addr, value_contents_raw (v), TYPE_LENGTH (value_type (v)));
+  v->lval = lval_memory;
+  v->location.address = addr;
+}
+
 void
 set_value_component_location (struct value *component,
 			      const struct value *whole)

gdb/value.h

@@ -1038,6 +1038,8 @@ extern struct value *value_copy (struct value *);
 
 extern struct value *value_non_lval (struct value *);
 
+extern void value_force_lval (struct value *, CORE_ADDR);
+
 extern void preserve_one_value (struct value *, struct objfile *, htab_t);
 
 /* From valops.c */