Convert the unavailable vector to be bit, not byte, based.

  https://sourceware.org/ml/gdb-patches/2013-12/msg00144.html

The vector of unavailable parts of a value is currently byte based.  Given
that we can model a value down to the bit level, we can potentially loose
information with the current implementation.  After this patch we model the
unavailable information in bits.

gdb/ChangeLog

	* dwarf2loc.c (read_pieced_value): Mark bits, not bytes
	unavailable, use correct bit length.
	* value.c (struct value): Extend comment on unavailable to
	indicate that it is bit based.
	(value_bits_available): New function.
	(value_bytes_available): Call value_bits_available.
	(value_entirely_available): Check against the bit length, not byte
	length.
	(mark_value_bits_unavailable): New function.
	(mark_value_bytes_unavailable): Move contents to
	mark_value_bits_unavailable, call to same.
	(memcmp_with_bit_offsets): New function.
	(value_available_contents_bits_eq): New function, takes the
	functionality from value_available_contents_eq but uses
	memcmp_with_bit_offsets now, and is bit not byte based.
	(value_available_contents_eq): Move implementation into
	value_available_contents_bits_eq, call to same.
	(value_contents_copy_raw): Work on bits, not bytes.
	(unpack_value_bits_as_long_1): Check availability in bits, not
	bytes.
	* value.h (value_bits_available): Declare new function.
	(mark_value_bits_unavailable): Declare new function.

gdb/testsuite/ChangeLog

	* gdb.trace/unavailable-dwarf-piece.c: New file.
	* gdb.trace/unavailable-dwarf-piece.exp: New file.

3 files changed, 425 insertions, 0 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index b9f98f7..0d768bc 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2013-12-17  Andrew Burgess  <aburgess@broadcom.com>
+
+	* gdb.trace/unavailable-dwarf-piece.c: New file.
+	* gdb.trace/unavailable-dwarf-piece.exp: New file.
+
 2013-12-15  Yao Qi  <yao@codesourcery.com>
 
 	* gdb.perf/skip-prologue.c: New.
diff --git a/gdb/testsuite/gdb.trace/unavailable-dwarf-piece.c b/gdb/testsuite/gdb.trace/unavailable-dwarf-piece.c
new file mode 100644
index 0000000..46474f2
--- /dev/null
+++ b/gdb/testsuite/gdb.trace/unavailable-dwarf-piece.c
@@ -0,0 +1,86 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2013 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/>.  */
+
+struct s
+{
+  unsigned char a;
+  unsigned char b;
+  unsigned char c;
+};
+
+struct t
+{
+  /* First, a complete byte.  */
+  unsigned char a;
+  /* Next, 8 single bits.  */
+  unsigned char b : 1;
+  unsigned char c : 1;
+  unsigned char d : 1;
+  unsigned char e : 1;
+  unsigned char f : 1;
+  unsigned char g : 1;
+  unsigned char h : 1;
+  unsigned char i : 1;
+  /* Now another byte.  */
+  unsigned char j;
+};
+
+void
+end (void)
+{
+  /* Nothing.  */
+}
+
+void
+dummy (void)
+{
+  /* Nothing.  */
+}
+
+int
+foo (struct s x, struct s y, struct s z)
+{
+  dummy ();
+  asm (".global foo_end_lbl\nfoo_end_lbl:");
+  return 0;
+}
+
+int
+bar (struct t x, struct t y, struct t z)
+{
+  dummy ();
+  asm (".global bar_end_lbl\nbar_end_lbl:");
+  return 0;
+}
+
+int
+main (void)
+{
+  struct s v = { 0, 1, 2 };
+  struct t w = { 5, 0, 1, 0, 1, 0, 1, 0, 1, 7 };
+  int ans;
+
+  ans = foo (v, v, v);
+
+  end ();
+
+  ans = bar (w, w, w);
+
+  end ();
+
+  return ans;
+}
diff --git a/gdb/testsuite/gdb.trace/unavailable-dwarf-piece.exp b/gdb/testsuite/gdb.trace/unavailable-dwarf-piece.exp
new file mode 100644
index 0000000..be38588
--- /dev/null
+++ b/gdb/testsuite/gdb.trace/unavailable-dwarf-piece.exp
@@ -0,0 +1,334 @@
+# Copyright (C) 2013 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/>.
+
+load_lib "trace-support.exp"
+load_lib dwarf.exp
+
+if {![dwarf2_support]} {
+    return 0
+}
+
+standard_testfile .c
+
+set asm_file "${testfile}-dbg.s"
+set opts {}
+
+if  { [gdb_compile ${srcdir}/${subdir}/${srcfile} ${binfile}1.o \
+	   object {nodebug}] != "" } {
+    return -1
+}
+
+Dwarf::assemble $asm_file {
+    declare_labels uchar_label struct_s_label foo_label struct_t_label bar_label
+
+    cu {} {
+	compile_unit {{language @DW_LANG_C}} {
+	    uchar_label: DW_TAG_base_type {
+		{name "unsigned char"}
+		{byte_size 1 DW_FORM_sdata}
+		{encoding @DW_ATE_unsigned_char}
+	    }
+
+	    struct_s_label: DW_TAG_structure_type {
+		{name s}
+		{byte_size 3 DW_FORM_sdata}
+		{decl_file 1}
+		{decl_line 1}
+	    } {
+		DW_TAG_member {
+		    {name a}
+		    {type :$uchar_label}
+		    {data_member_location {
+			DW_OP_plus_uconst 0
+		    } SPECIAL_expr}
+		}
+		DW_TAG_member {
+		    {name b}
+		    {type :$uchar_label}
+		    {data_member_location {
+			DW_OP_plus_uconst 1
+		    } SPECIAL_expr}
+		}
+		DW_TAG_member {
+		    {name c}
+		    {type :$uchar_label}
+		    {data_member_location {
+			DW_OP_plus_uconst 2
+		    } SPECIAL_expr}
+		}
+	    }
+
+	    struct_t_label: DW_TAG_structure_type {
+		{name t}
+		{byte_size 3 DW_FORM_sdata}
+		{decl_file 1}
+		{decl_line 1}
+	    } {
+		DW_TAG_member {
+		    {name a}
+		    {type :$uchar_label}
+		    {data_member_location {
+			DW_OP_plus_uconst 0
+		    } SPECIAL_expr}
+		}
+		DW_TAG_member {
+		    {name b}
+		    {type :$uchar_label}
+		    {byte_size 1 DW_FORM_sdata}
+		    {bit_size 1 DW_FORM_sdata}
+		    {bit_offset 7 DW_FORM_sdata}
+		    {data_member_location {
+			DW_OP_plus_uconst 1
+		    } SPECIAL_expr}
+		}
+		DW_TAG_member {
+		    {name c}
+		    {type :$uchar_label}
+		    {byte_size 1 DW_FORM_sdata}
+		    {bit_size 1 DW_FORM_sdata}
+		    {bit_offset 6 DW_FORM_sdata}
+		    {data_member_location {
+			DW_OP_plus_uconst 1
+		    } SPECIAL_expr}
+		}
+		DW_TAG_member {
+		    {name d}
+		    {type :$uchar_label}
+		    {byte_size 1 DW_FORM_sdata}
+		    {bit_size 1 DW_FORM_sdata}
+		    {bit_offset 5 DW_FORM_sdata}
+		    {data_member_location {
+			DW_OP_plus_uconst 1
+		    } SPECIAL_expr}
+		}
+		DW_TAG_member {
+		    {name e}
+		    {type :$uchar_label}
+		    {byte_size 1 DW_FORM_sdata}
+		    {bit_size 1 DW_FORM_sdata}
+		    {bit_offset 4 DW_FORM_sdata}
+		    {data_member_location {
+			DW_OP_plus_uconst 1
+		    } SPECIAL_expr}
+		}
+		DW_TAG_member {
+		    {name f}
+		    {type :$uchar_label}
+		    {byte_size 1 DW_FORM_sdata}
+		    {bit_size 1 DW_FORM_sdata}
+		    {bit_offset 3 DW_FORM_sdata}
+		    {data_member_location {
+			DW_OP_plus_uconst 1
+		    } SPECIAL_expr}
+		}
+		DW_TAG_member {
+		    {name g}
+		    {type :$uchar_label}
+		    {byte_size 1 DW_FORM_sdata}
+		    {bit_size 1 DW_FORM_sdata}
+		    {bit_offset 2 DW_FORM_sdata}
+		    {data_member_location {
+			DW_OP_plus_uconst 1
+		    } SPECIAL_expr}
+		}
+		DW_TAG_member {
+		    {name h}
+		    {type :$uchar_label}
+		    {byte_size 1 DW_FORM_sdata}
+		    {bit_size 1 DW_FORM_sdata}
+		    {bit_offset 1 DW_FORM_sdata}
+		    {data_member_location {
+			DW_OP_plus_uconst 1
+		    } SPECIAL_expr}
+		}
+		DW_TAG_member {
+		    {name i}
+		    {type :$uchar_label}
+		    {byte_size 1 DW_FORM_sdata}
+		    {bit_size 1 DW_FORM_sdata}
+		    {bit_offset 0 DW_FORM_sdata}
+		    {data_member_location {
+			DW_OP_plus_uconst 1
+		    } SPECIAL_expr}
+		}
+		DW_TAG_member {
+		    {name j}
+		    {type :$uchar_label}
+		    {data_member_location {
+			DW_OP_plus_uconst 2
+		    } SPECIAL_expr}
+		}
+	    }
+
+	    DW_TAG_subprogram {
+		{name foo}
+		{decl_file 1}
+		{low_pc foo addr}
+		{high_pc foo_end_lbl addr}
+	    } {
+		DW_TAG_formal_parameter {
+		    {type :$struct_s_label}
+		    {name x}
+		    {location {
+			DW_OP_lit0
+			DW_OP_stack_value
+			DW_OP_piece 2
+			DW_OP_reg0
+			DW_OP_piece 1
+		    } SPECIAL_expr}
+		}
+		DW_TAG_formal_parameter {
+		    {type :$struct_s_label}
+		    {name y}
+		    {location {
+			DW_OP_lit0
+			DW_OP_stack_value
+			DW_OP_piece 1
+			DW_OP_reg0
+			DW_OP_piece 1
+			DW_OP_lit0
+			DW_OP_stack_value
+			DW_OP_piece 1
+		    } SPECIAL_expr}
+		}
+		DW_TAG_formal_parameter {
+		    {type :$struct_s_label}
+		    {name z}
+		    {location {
+			DW_OP_reg0
+			DW_OP_piece 1
+			DW_OP_lit0
+			DW_OP_stack_value
+			DW_OP_piece 2
+		    } SPECIAL_expr}
+		}
+	    }
+
+
+	    DW_TAG_subprogram {
+		{name bar}
+		{decl_file 1}
+		{low_pc bar addr}
+		{high_pc bar_end_lbl addr}
+	    } {
+		DW_TAG_formal_parameter {
+		    {type :$struct_t_label}
+		    {name x}
+		    {location {
+			DW_OP_lit0
+			DW_OP_stack_value
+			DW_OP_piece 1
+			DW_OP_reg0
+			DW_OP_bit_piece 1 0
+			DW_OP_lit0
+			DW_OP_stack_value
+			DW_OP_bit_piece 7 0
+			DW_OP_lit0
+			DW_OP_stack_value
+			DW_OP_piece 1
+		    } SPECIAL_expr}
+		}
+		DW_TAG_formal_parameter {
+		    {type :$struct_t_label}
+		    {name y}
+		    {location {
+			DW_OP_lit0
+			DW_OP_stack_value
+			DW_OP_piece 1
+			DW_OP_lit0
+			DW_OP_stack_value
+			DW_OP_bit_piece 3 0
+			DW_OP_reg0
+			DW_OP_bit_piece 1 0
+			DW_OP_lit0
+			DW_OP_stack_value
+			DW_OP_bit_piece 4 0
+			DW_OP_lit0
+			DW_OP_stack_value
+			DW_OP_piece 1
+		    } SPECIAL_expr}
+		}
+		DW_TAG_formal_parameter {
+		    {type :$struct_t_label}
+		    {name z}
+		    {location {
+			DW_OP_lit0
+			DW_OP_stack_value
+			DW_OP_piece 1
+			DW_OP_lit0
+			DW_OP_stack_value
+			DW_OP_bit_piece 7 0
+			DW_OP_reg0
+			DW_OP_bit_piece 1 0
+			DW_OP_lit0
+			DW_OP_stack_value
+			DW_OP_piece 1
+		    } SPECIAL_expr}
+		}
+	    }
+
+	}
+    }
+}
+
+if  { [gdb_compile ${asm_file} ${binfile}2.o object {nodebug}] != "" } {
+    return -1
+}
+
+if  { [gdb_compile [list ${binfile}1.o ${binfile}2.o] ${binfile} \
+	   executable {}] != "" } {
+    return -1
+}
+
+clean_restart ${testfile}
+
+if ![runto_main] {
+    return -1
+}
+
+if ![gdb_target_supports_trace] {
+    unsupported "target does not support trace"
+    return -1
+}
+
+gdb_breakpoint "end"
+
+with_test_prefix "tracing foo" {
+    gdb_test "trace foo" ".*"
+    gdb_test_no_output "tstart"
+    gdb_test "continue" "Continuing\\.\[ \r\n\]+Breakpoint.*"
+    gdb_test_no_output "tstop"
+
+    gdb_test "tfind 0" "Found trace frame 0, tracepoint .*"
+    gdb_test "p/d x" "\\\$${decimal} = {a = 0, b = 0, c = <unavailable>}"
+    gdb_test "p/d y" "\\\$${decimal} = {a = 0, b = <unavailable>, c = 0}"
+    gdb_test "p/d z" "\\\$${decimal} = {a = <unavailable>, b = 0, c = 0}"
+
+    gdb_test "tfind none" "No longer looking at any trace frame.*"
+}
+
+with_test_prefix "tracing bar" {
+    gdb_test "trace bar" ".*"
+    gdb_test_no_output "tstart"
+    gdb_test "continue" "Continuing\\.\[ \r\n\]+Breakpoint.*"
+    gdb_test_no_output "tstop"
+
+    gdb_test "tfind 0" "Found trace frame 0, tracepoint .*"
+    gdb_test "p/d x" "\\\$${decimal} = {a = 0, b = <unavailable>, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, i = 0, j = 0}"
+    gdb_test "p/d y" "\\\$${decimal} = {a = 0, b = 0, c = 0, d = 0, e = <unavailable>, f = 0, g = 0, h = 0, i = 0, j = 0}"
+    gdb_test "p/d z" "\\\$${decimal} = {a = 0, b = 0, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, i = <unavailable>, j = 0}"
+
+    gdb_test "tfind none" "No longer looking at any trace frame.*"
+}