[PATCH 3/3] Test case for DW_OP_GNU_variable_value

[Kevin Buettner <kevinb@redhat.com>]

gdb/testsuite/ChangeLog:
    
    	* gdb.dwarf2/varval.c: New file.
    	* gdb.dwarf2/varval.exp: New file.
---
 gdb/testsuite/gdb.dwarf2/varval.c   |  30 ++++
 gdb/testsuite/gdb.dwarf2/varval.exp | 279 ++++++++++++++++++++++++++++++++++++
 2 files changed, 309 insertions(+)

diff --git a/gdb/testsuite/gdb.dwarf2/varval.c b/gdb/testsuite/gdb.dwarf2/varval.c
new file mode 100644
index 0000000..ce5592e
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/varval.c
@@ -0,0 +1,30 @@
+/* Copyright (C) 2018 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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/>.  */
+
+/* Test program for DW_OP_GNU_variable_value.  */
+
+int var_a = 8;
+int var_b = 3;
+int *var_p = &var_b;
+struct { int a, b, c, d, e, f, g, h; } var_s = { 101, 102, 103, 104, 105, 106, 107, 108 };
+
+int
+main (void)
+{
+  asm ("main_label: .globl main_label");
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.dwarf2/varval.exp b/gdb/testsuite/gdb.dwarf2/varval.exp
new file mode 100644
index 0000000..f4319ae
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/varval.exp
@@ -0,0 +1,279 @@
+# Copyright 2018 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/>.
+
+# Test support for DW_OP_GNU_variable_value. 
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if ![dwarf2_support] {
+    return 0
+}
+
+# We'll place the output of Dwarf::assemble in varval.S.
+standard_testfile .c .S
+
+# ${testfile} is now "varval".  srcfile2 is "varval.S".
+set executable ${testfile}
+set asm_file [standard_output_file ${srcfile2}]
+
+# We need to know the size of integer and address types in order
+# to write some of the debugging info we'd like to generate.
+#
+# For that, we ask GDB by debugging our varval program.
+# Any program would do, but since we already have varval
+# specifically for this testcase, might as well use that.
+if [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] {
+    return -1
+}
+
+# Create the DWARF.  
+Dwarf::assemble ${asm_file} {
+    global srcdir subdir srcfile
+
+    cu {} {
+	DW_TAG_compile_unit {
+	    {DW_AT_language @DW_LANG_C_plus_plus}
+	} {
+	    declare_labels int_label ptr_label struct_label var_a_label \
+	                   var_b_label var_c_label var_p_label var_bad_label \
+			   varval_label var_s_label var_untyped_label
+
+	    set int_size [get_sizeof "int" -1]
+
+	    # gdb always assumes references are implemented as pointers.
+	    set addr_size [get_sizeof "void *" -1]
+
+	    int_label: DW_TAG_base_type {
+		{DW_AT_byte_size ${int_size} DW_FORM_udata}
+		{DW_AT_encoding @DW_ATE_signed}
+		{DW_AT_name "int"}
+	    }
+
+	    ptr_label: DW_TAG_pointer_type {
+		{DW_AT_type :$int_label}
+	    }
+
+	    var_a_label: DW_TAG_variable {
+		{DW_AT_name "var_a"}
+		{DW_AT_type :${int_label}}
+		{DW_AT_external 1 DW_FORM_flag}
+		{DW_AT_location {DW_OP_addr [gdb_target_symbol "var_a"]} SPECIAL_expr}
+	    }
+
+	    var_b_label: DW_TAG_variable {
+		{DW_AT_name "var_b"}
+		{DW_AT_type :${int_label}}
+		{DW_AT_external 1 DW_FORM_flag}
+		{DW_AT_location {DW_OP_addr [gdb_target_symbol "var_b"]} SPECIAL_expr}
+	    }
+
+	    var_c_label: DW_TAG_variable {
+		{DW_AT_name "var_c"}
+		{DW_AT_type :${int_label}}
+		{DW_AT_external 1 DW_FORM_flag}
+		{DW_AT_const_value 53 DW_FORM_sdata}
+	    }
+
+	    var_p_label: DW_TAG_variable {
+		{DW_AT_name "var_p"}
+		{DW_AT_type :${ptr_label}}
+		{DW_AT_external 1 DW_FORM_flag}
+		{DW_AT_location {DW_OP_addr [gdb_target_symbol "var_p"]} SPECIAL_expr}
+	    }
+
+	    var_bad_label: DW_TAG_variable {
+		{DW_AT_name "var_bad"}
+		{DW_AT_type :${int_label}}
+		{DW_AT_external 1 DW_FORM_flag}
+	    }
+
+	    struct_label: DW_TAG_structure_type {
+		{DW_AT_byte_size 8*$int_size DW_FORM_sdata}
+	    } {
+		DW_TAG_member {
+		    {DW_AT_name "a"}
+		    {DW_AT_type :$int_label}
+		    {DW_AT_data_member_location 0*$int_size DW_FORM_udata}
+		}
+		DW_TAG_member {
+		    {DW_AT_name "b"}
+		    {DW_AT_type :$int_label}
+		    {DW_AT_data_member_location 1*$int_size DW_FORM_udata}
+		}
+		DW_TAG_member {
+		    {DW_AT_name "c"}
+		    {DW_AT_type :$int_label}
+		    {DW_AT_data_member_location 2*$int_size DW_FORM_udata}
+		}
+		DW_TAG_member {
+		    {DW_AT_name "d"}
+		    {DW_AT_type :$int_label}
+		    {DW_AT_data_member_location 3*$int_size DW_FORM_udata}
+		}
+		DW_TAG_member {
+		    {DW_AT_name "e"}
+		    {DW_AT_type :$int_label}
+		    {DW_AT_data_member_location 4*$int_size DW_FORM_udata}
+		}
+		DW_TAG_member {
+		    {DW_AT_name "f"}
+		    {DW_AT_type :$int_label}
+		    {DW_AT_data_member_location 5*$int_size DW_FORM_udata}
+		}
+		DW_TAG_member {
+		    {DW_AT_name "g"}
+		    {DW_AT_type :$int_label}
+		    {DW_AT_data_member_location 6*$int_size DW_FORM_udata}
+		}
+		DW_TAG_member {
+		    {DW_AT_name "h"}
+		    {DW_AT_type :$int_label}
+		    {DW_AT_data_member_location 7*$int_size DW_FORM_udata}
+		}
+	    }
+
+	    var_s_label: DW_TAG_variable {
+		{DW_AT_name "var_s"}
+		{DW_AT_type :${struct_label}}
+		{DW_AT_external 1 DW_FORM_flag}
+		{DW_AT_location {DW_OP_addr [gdb_target_symbol "var_s"]} SPECIAL_expr}
+	    }
+
+	    var_untyped_label: DW_TAG_variable {
+		{DW_AT_name "var_untyped"}
+		{DW_AT_external 1 DW_FORM_flag}
+		{DW_AT_location {DW_OP_addr [gdb_target_symbol "var_b"]} SPECIAL_expr}
+	    }
+
+	    DW_TAG_subprogram {
+		{MACRO_AT_func { "main" "${srcdir}/${subdir}/${srcfile}" }}
+		{DW_AT_type :${int_label}}
+		{DW_AT_external 1 DW_FORM_flag}
+	    } {
+		varval_label: DW_TAG_variable {
+		    {DW_AT_name "varval"}
+		    {DW_AT_type :${int_label}}
+		    {DW_AT_location {
+			DW_OP_GNU_variable_value ${var_a_label}
+			DW_OP_stack_value
+		    } SPECIAL_expr}
+		}
+		DW_TAG_variable {
+		    {DW_AT_name "constval"}
+		    {DW_AT_type :${int_label}}
+		    {DW_AT_location {
+			DW_OP_GNU_variable_value ${var_c_label}
+			DW_OP_stack_value
+		    } SPECIAL_expr}
+		}
+		DW_TAG_variable {
+		    {DW_AT_name "mixedval"}
+		    {DW_AT_type :${int_label}}
+		    {DW_AT_location {
+			DW_OP_GNU_variable_value ${var_c_label}
+			DW_OP_GNU_variable_value ${var_b_label}
+			DW_OP_div
+			DW_OP_GNU_variable_value ${varval_label}
+			DW_OP_plus
+			DW_OP_dup
+			DW_OP_plus
+			DW_OP_GNU_variable_value ${varval_label}
+			DW_OP_minus
+			DW_OP_stack_value
+		    } SPECIAL_expr}
+		}
+		DW_TAG_variable {
+		    {DW_AT_name "pointerval"}
+		    {DW_AT_type :${ptr_label}}
+		    {DW_AT_location {
+			DW_OP_GNU_variable_value ${var_p_label}
+			DW_OP_stack_value
+		    } SPECIAL_expr}
+		}
+		DW_TAG_variable {
+		    {DW_AT_name "badval"}
+		    {DW_AT_type :${int_label}}
+		    {DW_AT_location {
+			DW_OP_GNU_variable_value ${var_bad_label}
+			DW_OP_stack_value
+		    } SPECIAL_expr}
+		}
+		DW_TAG_variable {
+		    {DW_AT_name "structval"}
+		    {DW_AT_type :${struct_label}}
+		    {DW_AT_location {
+			DW_OP_GNU_variable_value ${var_s_label}
+			DW_OP_stack_value
+		    } SPECIAL_expr}
+		}
+		DW_TAG_variable {
+		    {DW_AT_name "untypedval"}
+		    {DW_AT_location {
+			DW_OP_GNU_variable_value ${var_untyped_label}
+			DW_OP_stack_value
+		    } SPECIAL_expr}
+		}
+		DW_TAG_variable {
+		    {DW_AT_name "bad_die_val1"}
+		    {DW_AT_location {
+			DW_OP_GNU_variable_value 0xabcdef11
+			DW_OP_stack_value
+		    } SPECIAL_expr}
+		}
+		DW_TAG_variable {
+		    {DW_AT_name "bad_die_val2"}
+		    {DW_AT_location {
+			DW_OP_GNU_variable_value ${ptr_label}+1
+			DW_OP_stack_value
+		    } SPECIAL_expr}
+		}
+	    }
+	}
+    }
+}
+
+if [prepare_for_testing "failed to prepare" ${executable} [list ${asm_file} ${srcfile}] {}] {
+    return -1
+}
+
+# DW_OP_GNU_variable_value implementation requires a valid frame.
+if ![runto_main] {
+    return -1
+}
+
+gdb_test "print varval" "= 8"
+gdb_test "print constval" "= 53"
+gdb_test "print mixedval" "= 42"
+gdb_test "print pointerval" "= \\(int \\*\\) $hex <var_b>"
+gdb_test "print *pointerval" "= 3"
+gdb_test "print badval" "value has been optimized out"
+
+# Jakub says:  "The intended behavior is that the debug info consumer
+# computes the value of that referenced variable at the current PC,
+# and if it can compute it and pushes the value as a generic type
+# integer into the DWARF stack (it is really only meaningful when
+# referring to integral/pointer typed variables)."
+
+gdb_test "print structval" \
+         "Type of DW_OP_GNU_variable_value DIE must be an integer or pointer\\."
+
+gdb_test "print untypedval" \
+         "Type of DW_OP_GNU_variable_value DIE must be an integer or pointer\\."
+
+gdb_test "print bad_die_val1" \
+         "invalid dwarf2 offset 0xabcdef11"
+gdb_test "print bad_die_val2" \
+         "Bad DW_OP_GNU_variable_value DIE\\."