[v2,8/8] Test case for functions with non-contiguous ranges

Message ID 20180813171404.0a582d77@pinnacle.lan
State Superseded
Headers show
Series
  • Non-contiguous address range support
Related show

Commit Message

Kevin Buettner Aug. 14, 2018, 12:14 a.m.
See comments in the new files for what this is about - I tried to
explain it all there.

gdb/testsuite/ChangeLog:
    
    	* gdb.dwarf2/dw2-ranges-func.c: New file.
    	* gdb.dwarf2/dw2-ranges-func.exp: New file.
---
 gdb/testsuite/gdb.dwarf2/dw2-ranges-func.c   |  78 ++++++
 gdb/testsuite/gdb.dwarf2/dw2-ranges-func.exp | 400 +++++++++++++++++++++++++++
 2 files changed, 478 insertions(+)

Comments

Pedro Alves Aug. 21, 2018, 7:25 p.m. | #1
On 08/14/2018 01:14 AM, Kevin Buettner wrote:
> See comments in the new files for what this is about - I tried to

> explain it all there.

> 

> gdb/testsuite/ChangeLog:

>     

>     	* gdb.dwarf2/dw2-ranges-func.c: New file.

>     	* gdb.dwarf2/dw2-ranges-func.exp: New file.

> ---

>  gdb/testsuite/gdb.dwarf2/dw2-ranges-func.c   |  78 ++++++

>  gdb/testsuite/gdb.dwarf2/dw2-ranges-func.exp | 400 +++++++++++++++++++++++++++

>  2 files changed, 478 insertions(+)

> 

> diff --git a/gdb/testsuite/gdb.dwarf2/dw2-ranges-func.c b/gdb/testsuite/gdb.dwarf2/dw2-ranges-func.c

> new file mode 100644

> index 0000000..864803c

> --- /dev/null

> +++ b/gdb/testsuite/gdb.dwarf2/dw2-ranges-func.c

> @@ -0,0 +1,78 @@

> +/* 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/>.  */

> +

> +/* The idea here is to, via use of the dwarf assembler, create a function

> +   which occupies two non-contiguous address ranges.

> +

> +   foo_low and foo will be combined into a single function foo with a

> +   function bar in between these two ranges.

> +

> +   This test case was motivated by a bug in which a function which

> +   occupied two non-contiguous address ranges was calling another

> +   function which resides in between these ranges.  So we end up with

> +   a situation in which the low/start address of our constructed foo

> +   (in this case) will be less than any of the addresses in bar, but

> +   the high/end address of foo will be greater than any of bar's

> +   addresses.

> +

> +   This situation was causing a problem in the caching code of

> +   find_pc_partial_function:  When the low and high addresses of foo

> +   are placed in the cache, the simple check that was used to see if

> +   the cache was applicable would (incorrectly) succeed when presented

> +   with an address in bar.  I.e. an address in bar presented as an

> +   input to find_pc_partial_function could produce the answer "this

> +   address belongs to foo".  */

> +

> +volatile int e = 0;

> +

> +void

> +baz (void)

> +{

> +  asm ("baz_label: .globl baz_label");

> +}						/* baz end */

> +

> +void

> +foo_low (void)

> +{						/* foo_low prologue */

> +  asm ("foo_low_label: .globl foo_low_label");

> +  baz ();					/* foo_low baz call */

> +  asm ("foo_low_label2: .globl foo_low_label2");

> +}						/* foo_low end */

> +

> +void

> +bar (void)

> +{

> +  asm ("bar_label: .globl bar_label");

> +}						/* bar end */

> +

> +void

> +foo (void)

> +{						/* foo prologue */

> +  asm ("foo_label: .globl foo_label");

> +  bar ();					/* foo bar call */

> +  asm ("foo_label2: .globl foo_label2");

> +  if (e) foo_low ();				/* foo foo_low call */

> +  asm ("foo_label3: .globl foo_label3");

> +}						/* foo end */

> +

> +int

> +main (void)

> +{						/* main prologue */

> +  asm ("main_label: .globl main_label");

> +  foo ();					/* main foo call */

> +  asm ("main_label2: .globl main_label2");

> +  return 0;					/* main return */

> +}						/* main end */

> +

> diff --git a/gdb/testsuite/gdb.dwarf2/dw2-ranges-func.exp b/gdb/testsuite/gdb.dwarf2/dw2-ranges-func.exp

> new file mode 100644

> index 0000000..227c753

> --- /dev/null

> +++ b/gdb/testsuite/gdb.dwarf2/dw2-ranges-func.exp

> @@ -0,0 +1,400 @@

> +# 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/>.

> +load_lib dwarf.exp

> +

> +# Test DW_AT_ranges in the context of a subprogram scope.

> +

> +# This test can only be run on targets which support DWARF-2 and use gas.

> +if {![dwarf2_support]} {

> +    unsupported "dwarf2 support required for this test"

> +    return 0

> +}

> +

> +if [get_compiler_info] {

> +    return -1

> +}

> +if !$gcc_compiled {

> +    unsupported "gcc required for this test"

> +    return 0

> +}

> +

> +standard_testfile dw2-ranges-func.c dw2-ranges-func-dw.S

> +

> +# 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 test program.  Any program

> +# would do, but since we already have it specifically for this

> +# testcase, might as well use that.

> +

> +if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] } {

> +    return -1

> +}

> +

> +set asm_file [standard_output_file $srcfile2]

> +Dwarf::assemble $asm_file {

> +    global srcdir subdir srcfile srcfile2

> +    declare_labels integer_label volatile_label func_ranges_label cu_ranges_label L

> +    set int_size [get_sizeof "int" 4]

> +

> +    # Find start address and length for our functions.

> +    lassign [function_range main [list ${srcdir}/${subdir}/$srcfile]] \

> +	main_start main_len

> +    lassign [function_range foo [list ${srcdir}/${subdir}/$srcfile]] \

> +	foo_start foo_len

> +    set foo_end {$foo_start + $foo_len}

> +    lassign [function_range foo_low [list ${srcdir}/${subdir}/$srcfile]] \

> +	foo_low_start foo_low_len

> +    set foo_low_end {$foo_low_start + $foo_low_len}

> +    lassign [function_range bar [list ${srcdir}/${subdir}/$srcfile]] \

> +	bar_start bar_len

> +    lassign [function_range baz [list ${srcdir}/${subdir}/$srcfile]] \

> +	baz_start baz_len

> +

> +    set e_var [gdb_target_symbol e]

> +

> +    cu {} {

> +	compile_unit {

> +	    {language @DW_LANG_C}

> +	    {name dw-ranges-func.c}

> +	    {stmt_list $L DW_FORM_sec_offset}

> +	    {low_pc 0 addr}

> +	    {ranges ${cu_ranges_label} DW_FORM_sec_offset}

> +	} {

> +            integer_label: DW_TAG_base_type {

> +                {DW_AT_byte_size $int_size DW_FORM_sdata}

> +                {DW_AT_encoding  @DW_ATE_signed}

> +                {DW_AT_name      integer}

> +            }


Tab vs spaces mixup here.

> +	    volatile_label: DW_TAG_volatile_type {

> +		{type :$integer_label}

> +	    }

> +	    DW_TAG_variable {

> +		{name e}

> +		{external 1 flag}

> +		{type :$volatile_label}

> +		{location {addr $e_var} SPECIAL_expr}

> +	    }

> +	    subprogram {

> +		{external 1 flag}

> +		{name main}

> +		{DW_AT_type :$integer_label}

> +		{low_pc $main_start addr}

> +		{high_pc $main_len DW_FORM_data4}

> +	    }

> +	    subprogram {

> +		{external 1 flag}

> +		{name foo}

> +		{ranges ${func_ranges_label} DW_FORM_sec_offset}

> +	    }

> +	    subprogram {

> +		{external 1 flag}

> +		{name bar}

> +		{low_pc $bar_start addr}

> +		{high_pc $bar_len DW_FORM_data4}

> +	    }

> +	    subprogram {

> +		{external 1 flag}

> +		{name baz}

> +		{low_pc $baz_start addr}

> +		{high_pc $baz_len DW_FORM_data4}

> +	    }

> +	}

> +    }

> +

> +    lines {version 2} L {

> +	include_dir "${srcdir}/${subdir}"

> +	file_name "$srcfile" 1

> +

> +	# Generate a line table program. I attempted to make it reasonably

> +	# accurate as it made debugging the test case easier.


Double space after ".".  

Nit: I'm not a big fan of using "I", "me", etc. in comments, it reads
a bit awkwardly personal to me.  If several people edit these
comments later on, who becomes the "I" then?

> +clean_restart ${testfile}

> +if ![runto_main] {

> +    return -1

> +}


Should move these "clean_restart / runto_main" calls into the
following with_test_prefix, in case the runto_main issues
an internal FAIL.

> +

> +with_test_prefix "step-test-2" {

> +    # Note that the RE used for the following test will fail when the

> +    # breakpoint has been set on multiple locations. E.g. "(2 locations)". 

> +    # This is intentional since that behavior is one of the bugs that

> +    # this test case tests for.

> +    gdb_test "break foo" \

> +	"Breakpoint.*at.* file .*$srcfile, line \\d+\\." \

> +	"break foo"

> +

> +    # Continue to foo.  Allow execution to stop either on the prologue

> +    # or on the call to bar since either behavior is acceptable though

> +    # the latter is preferred.

> +    set test "continue to foo"

> +    gdb_test_multiple "continue" $test {

> +	-re "Breakpoint \\d+, foo \\(\\).*foo prologue.*${gdb_prompt}" {

> +	    pass $test

> +	    gdb_test "step" \

> +		     "foo bar call .*" \

> +		     "step to call of bar after landing on prologue"

> +	}

> +	-re "Breakpoint \\d+, foo \\(\\).*foo bar call.*${gdb_prompt}" {

> +	    pass $test

> +	}

> +    }

> +

> +    gdb_test "step" \

> +	"bar \\(\\).*bar end.*" \

> +	"step into bar"

> +

> +    gdb_test "step" \

> +	"foo \\(\\).*foo foo_low call.*" \

> +	"step out of bar, back into foo"

> +}

> +

> +clean_restart ${testfile}

> +if ![runto_main] {

> +    return -1

> +}

> +

> +# Disassembly of foo should have multiple address ranges.

> +# Note: I couldn't get $hex to work in the gdb_test_sequence regex.


Did you try to use [list .....] instead of {.....} ?

> +gdb_test_sequence "disassemble foo" "" {

> +    "Dump of assembler code for function foo:"

> +    "Address range 0x[\\dabcdefABCDEF]+ to 0x[\\dabcdefABCDEF]+:"

> +    "   0x[\\dabcdefABCDEF]+ <\\+0>:"

> +    "Address range 0x[\\dabcdefABCDEF]+ to 0x[\\dabcdefABCDEF]+:"

> +    "   0x[\\dabcdefABCDEF]+ <(.+?)>:"

> +    "End of assembler dump\\." 

> +}

> +

> +set test "x/i foo_low"

> +gdb_test_multiple $test $test {

> +    -re "   ($hex) <foo.*?>.*${gdb_prompt}" {

> +        set foo_low_addr $expect_out(1,string)

> +	pass $test


Spaces vs tabs mixup, seemingly.

Also, this leaves "foo_low_addr" unset if the gdb_test_multiple
ever fails, leading to a TCL error when next foo_low_addr is
referenced.

The usual pattern around this is to default the variable,
something like:

set foo_low_addr -1
gdb_test_multiple $test $test {
    -re "   ($hex) <foo.*?>.*${gdb_prompt}" {
        set foo_low_addr $expect_out(1,string)
	pass $test
    }

> +    }

> +}

> +

> +set test "x/i foo"

> +gdb_test_multiple $test $test {

> +    -re "   ($hex) <foo.*?>.*${gdb_prompt}" {

> +        set foo_addr $expect_out(1,string)

> +	pass $test


Ditto, indentation and default.

> +    }

> +}

> +

> +gdb_assert {$foo_low_addr != $foo_addr} "foo and foo_low are at different addresses"

> +

> +# This more permissive RE for "break foo" will allow a breakpoint on

> +# multiple locations to PASS.  */

> +gdb_test "break foo" \

> +    "Breakpoint.*at.*" \

> +    "break foo (2nd time)"


Don't use tail parens for "(2nd time)":

  https://sourceware.org/gdb/wiki/GDBTestcaseCookbook#Do_not_use_.22tail_parentheses.22_on_test_messages

Use e.g., "break foo, 2nd time", or create a with_test_prefix
block, if it makes sense.

> +

> +gdb_test "break baz" \

> +    "Breakpoint.*at.* file .*$srcfile, line \\d+\\."

> +

> +gdb_test "continue" \

> +    "Breakpoint \\d+, foo \\(\\).*" \

> +    "Continue to foo"


Lowercase "continue".

> +

> +gdb_test_no_output "set variable e=1"

> +

> +# If GDB incorrectly places the foo breakpoint on multiple locations,

> +# then GDB will (incorrectly) stop in foo_low instead of in baz.

> +gdb_test "continue" \

> +    "Breakpoint \\d+, (?:$hex in )?baz \\(\\).*" \

> +    "Continue to baz"


Ditto.

> +

> +clean_restart ${testfile}

> +if ![runto_main] {

> +    return -1

> +}

> +

Thanks,
Pedro Alves

Patch

diff --git a/gdb/testsuite/gdb.dwarf2/dw2-ranges-func.c b/gdb/testsuite/gdb.dwarf2/dw2-ranges-func.c
new file mode 100644
index 0000000..864803c
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-ranges-func.c
@@ -0,0 +1,78 @@ 
+/* 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/>.  */
+
+/* The idea here is to, via use of the dwarf assembler, create a function
+   which occupies two non-contiguous address ranges.
+
+   foo_low and foo will be combined into a single function foo with a
+   function bar in between these two ranges.
+
+   This test case was motivated by a bug in which a function which
+   occupied two non-contiguous address ranges was calling another
+   function which resides in between these ranges.  So we end up with
+   a situation in which the low/start address of our constructed foo
+   (in this case) will be less than any of the addresses in bar, but
+   the high/end address of foo will be greater than any of bar's
+   addresses.
+
+   This situation was causing a problem in the caching code of
+   find_pc_partial_function:  When the low and high addresses of foo
+   are placed in the cache, the simple check that was used to see if
+   the cache was applicable would (incorrectly) succeed when presented
+   with an address in bar.  I.e. an address in bar presented as an
+   input to find_pc_partial_function could produce the answer "this
+   address belongs to foo".  */
+
+volatile int e = 0;
+
+void
+baz (void)
+{
+  asm ("baz_label: .globl baz_label");
+}						/* baz end */
+
+void
+foo_low (void)
+{						/* foo_low prologue */
+  asm ("foo_low_label: .globl foo_low_label");
+  baz ();					/* foo_low baz call */
+  asm ("foo_low_label2: .globl foo_low_label2");
+}						/* foo_low end */
+
+void
+bar (void)
+{
+  asm ("bar_label: .globl bar_label");
+}						/* bar end */
+
+void
+foo (void)
+{						/* foo prologue */
+  asm ("foo_label: .globl foo_label");
+  bar ();					/* foo bar call */
+  asm ("foo_label2: .globl foo_label2");
+  if (e) foo_low ();				/* foo foo_low call */
+  asm ("foo_label3: .globl foo_label3");
+}						/* foo end */
+
+int
+main (void)
+{						/* main prologue */
+  asm ("main_label: .globl main_label");
+  foo ();					/* main foo call */
+  asm ("main_label2: .globl main_label2");
+  return 0;					/* main return */
+}						/* main end */
+
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-ranges-func.exp b/gdb/testsuite/gdb.dwarf2/dw2-ranges-func.exp
new file mode 100644
index 0000000..227c753
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-ranges-func.exp
@@ -0,0 +1,400 @@ 
+# 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/>.
+load_lib dwarf.exp
+
+# Test DW_AT_ranges in the context of a subprogram scope.
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    unsupported "dwarf2 support required for this test"
+    return 0
+}
+
+if [get_compiler_info] {
+    return -1
+}
+if !$gcc_compiled {
+    unsupported "gcc required for this test"
+    return 0
+}
+
+standard_testfile dw2-ranges-func.c dw2-ranges-func-dw.S
+
+# 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 test program.  Any program
+# would do, but since we already have it specifically for this
+# testcase, might as well use that.
+
+if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] } {
+    return -1
+}
+
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+    global srcdir subdir srcfile srcfile2
+    declare_labels integer_label volatile_label func_ranges_label cu_ranges_label L
+    set int_size [get_sizeof "int" 4]
+
+    # Find start address and length for our functions.
+    lassign [function_range main [list ${srcdir}/${subdir}/$srcfile]] \
+	main_start main_len
+    lassign [function_range foo [list ${srcdir}/${subdir}/$srcfile]] \
+	foo_start foo_len
+    set foo_end {$foo_start + $foo_len}
+    lassign [function_range foo_low [list ${srcdir}/${subdir}/$srcfile]] \
+	foo_low_start foo_low_len
+    set foo_low_end {$foo_low_start + $foo_low_len}
+    lassign [function_range bar [list ${srcdir}/${subdir}/$srcfile]] \
+	bar_start bar_len
+    lassign [function_range baz [list ${srcdir}/${subdir}/$srcfile]] \
+	baz_start baz_len
+
+    set e_var [gdb_target_symbol e]
+
+    cu {} {
+	compile_unit {
+	    {language @DW_LANG_C}
+	    {name dw-ranges-func.c}
+	    {stmt_list $L DW_FORM_sec_offset}
+	    {low_pc 0 addr}
+	    {ranges ${cu_ranges_label} DW_FORM_sec_offset}
+	} {
+            integer_label: DW_TAG_base_type {
+                {DW_AT_byte_size $int_size DW_FORM_sdata}
+                {DW_AT_encoding  @DW_ATE_signed}
+                {DW_AT_name      integer}
+            }
+	    volatile_label: DW_TAG_volatile_type {
+		{type :$integer_label}
+	    }
+	    DW_TAG_variable {
+		{name e}
+		{external 1 flag}
+		{type :$volatile_label}
+		{location {addr $e_var} SPECIAL_expr}
+	    }
+	    subprogram {
+		{external 1 flag}
+		{name main}
+		{DW_AT_type :$integer_label}
+		{low_pc $main_start addr}
+		{high_pc $main_len DW_FORM_data4}
+	    }
+	    subprogram {
+		{external 1 flag}
+		{name foo}
+		{ranges ${func_ranges_label} DW_FORM_sec_offset}
+	    }
+	    subprogram {
+		{external 1 flag}
+		{name bar}
+		{low_pc $bar_start addr}
+		{high_pc $bar_len DW_FORM_data4}
+	    }
+	    subprogram {
+		{external 1 flag}
+		{name baz}
+		{low_pc $baz_start addr}
+		{high_pc $baz_len DW_FORM_data4}
+	    }
+	}
+    }
+
+    lines {version 2} L {
+	include_dir "${srcdir}/${subdir}"
+	file_name "$srcfile" 1
+
+	# Generate a line table program. I attempted to make it reasonably
+	# accurate as it made debugging the test case easier.
+	program {
+	    {DW_LNE_set_address $main_start}
+	    {DW_LNS_advance_line [expr [gdb_get_line_number "main prologue"] - 1]}
+	    {DW_LNS_copy}
+	    {DW_LNE_set_address main_label}
+	    {DW_LNS_advance_line [expr [gdb_get_line_number "main foo call"] - [gdb_get_line_number "main prologue"]]}
+	    {DW_LNS_copy}
+	    {DW_LNE_set_address main_label2}
+	    {DW_LNS_advance_line [expr [gdb_get_line_number "main return"] - [gdb_get_line_number "main foo call"]]}
+	    {DW_LNS_copy}
+	    {DW_LNE_set_address $main_start+$main_len}
+	    {DW_LNS_advance_line [expr [gdb_get_line_number "main end"] - [gdb_get_line_number "main return"] + 1]}
+	    {DW_LNS_copy}
+	    {DW_LNE_end_sequence}
+
+	    {DW_LNE_set_address $foo_start}
+	    {DW_LNS_advance_line [expr [gdb_get_line_number "foo prologue"] - 1] }
+	    {DW_LNS_copy}
+	    {DW_LNE_set_address foo_label}
+	    {DW_LNS_advance_line [expr [gdb_get_line_number "foo bar call"] - [gdb_get_line_number "foo prologue"]]}
+	    {DW_LNS_copy}
+	    {DW_LNE_set_address foo_label2}
+	    {DW_LNS_advance_line [expr [gdb_get_line_number "foo foo_low call"] - [gdb_get_line_number "foo bar call"]]}
+	    {DW_LNS_copy}
+	    {DW_LNE_set_address foo_label3}
+	    {DW_LNS_advance_line [expr [gdb_get_line_number "foo end"] - [gdb_get_line_number "foo foo_low call"]]}
+	    {DW_LNS_copy}
+	    {DW_LNE_set_address $foo_start+$foo_len}
+	    {DW_LNS_advance_line 1}
+	    {DW_LNS_copy}
+	    {DW_LNE_end_sequence}
+
+	    {DW_LNE_set_address $bar_start}
+	    {DW_LNS_advance_line [expr [gdb_get_line_number "bar end"] - 1]}
+	    {DW_LNS_copy}
+	    {DW_LNS_advance_pc $bar_len}
+	    {DW_LNS_advance_line 1}
+	    {DW_LNS_copy}
+	    {DW_LNE_end_sequence}
+
+	    {DW_LNE_set_address $baz_start}
+	    {DW_LNS_advance_line [expr [gdb_get_line_number "baz end"] - 1]}
+	    {DW_LNS_copy}
+	    {DW_LNS_advance_pc $baz_len}
+	    {DW_LNS_advance_line 1}
+	    {DW_LNS_copy}
+	    {DW_LNE_end_sequence}
+
+	    {DW_LNE_set_address $foo_low_start}
+	    {DW_LNS_advance_line [expr [gdb_get_line_number "foo_low prologue"] - 1]}
+	    {DW_LNS_copy}
+	    {DW_LNE_set_address foo_low_label}
+	    {DW_LNS_advance_line [expr [gdb_get_line_number "foo_low baz call"] - [gdb_get_line_number "foo_low prologue"]]}
+	    {DW_LNS_copy}
+	    {DW_LNE_set_address foo_low_label2}
+	    {DW_LNS_advance_line [expr [gdb_get_line_number "foo_low end"] - [gdb_get_line_number "foo_low baz call"]]}
+	    {DW_LNS_copy}
+	    {DW_LNE_set_address $foo_low_start$foo_low_len}
+	    {DW_LNS_advance_line 1}
+	    {DW_LNS_copy}
+	    {DW_LNE_end_sequence}
+	}
+    }
+
+    # Generate ranges data.
+    ranges {is_64 [is_64_target]} {
+	func_ranges_label: sequence {
+	    {range {$foo_start } $foo_end}
+	    {range {$foo_low_start} $foo_low_end}
+	}
+	cu_ranges_label: sequence {
+	    {range {$foo_start } $foo_end}
+	    {range {$foo_low_start} $foo_low_end}
+	    {range {$main_start} $main_start + $main_len}
+	    {range {$bar_start} $bar_start + $bar_len}
+	    {range {$baz_start} $baz_start + $baz_len}
+	}
+    }
+}
+
+if { [prepare_for_testing "failed to prepare" ${testfile} \
+	  [list $srcfile $asm_file] {nodebug}] } {
+    return -1
+}
+
+if ![runto_main] {
+    return -1
+}
+
+set main_prologue_line_num [gdb_get_line_number "main prologue"]
+# Do a sanity check to make sure that line number info is available.
+gdb_test "info line main" \
+    "Line ${main_prologue_line_num} of .* starts at address .* and ends at .*"
+
+with_test_prefix "step-test-1" {
+    set bp_foo_bar [gdb_get_line_number "foo bar call"]
+
+    gdb_test "break $bp_foo_bar" \
+	"Breakpoint.*at.* file .*$srcfile, line $bp_foo_bar\\." \
+	"break at call to bar"
+
+    gdb_test "continue" \
+	"Continuing\\..*Breakpoint \[0-9\]+, foo \\(\\).*$bp_foo_bar\\s+bar\\s\\(\\);.*foo bar call.*" \
+	"continue to call of bar"
+
+    gdb_test "step" \
+	"bar \\(\\).*bar end.*" \
+	"step into bar"
+
+    gdb_test "step" \
+	"foo \\(\\).*foo foo_low call.*" \
+	"step out of bar, back into foo"
+}
+
+clean_restart ${testfile}
+if ![runto_main] {
+    return -1
+}
+
+with_test_prefix "step-test-2" {
+    # Note that the RE used for the following test will fail when the
+    # breakpoint has been set on multiple locations. E.g. "(2 locations)". 
+    # This is intentional since that behavior is one of the bugs that
+    # this test case tests for.
+    gdb_test "break foo" \
+	"Breakpoint.*at.* file .*$srcfile, line \\d+\\." \
+	"break foo"
+
+    # Continue to foo.  Allow execution to stop either on the prologue
+    # or on the call to bar since either behavior is acceptable though
+    # the latter is preferred.
+    set test "continue to foo"
+    gdb_test_multiple "continue" $test {
+	-re "Breakpoint \\d+, foo \\(\\).*foo prologue.*${gdb_prompt}" {
+	    pass $test
+	    gdb_test "step" \
+		     "foo bar call .*" \
+		     "step to call of bar after landing on prologue"
+	}
+	-re "Breakpoint \\d+, foo \\(\\).*foo bar call.*${gdb_prompt}" {
+	    pass $test
+	}
+    }
+
+    gdb_test "step" \
+	"bar \\(\\).*bar end.*" \
+	"step into bar"
+
+    gdb_test "step" \
+	"foo \\(\\).*foo foo_low call.*" \
+	"step out of bar, back into foo"
+}
+
+clean_restart ${testfile}
+if ![runto_main] {
+    return -1
+}
+
+# Disassembly of foo should have multiple address ranges.
+# Note: I couldn't get $hex to work in the gdb_test_sequence regex.
+gdb_test_sequence "disassemble foo" "" {
+    "Dump of assembler code for function foo:"
+    "Address range 0x[\\dabcdefABCDEF]+ to 0x[\\dabcdefABCDEF]+:"
+    "   0x[\\dabcdefABCDEF]+ <\\+0>:"
+    "Address range 0x[\\dabcdefABCDEF]+ to 0x[\\dabcdefABCDEF]+:"
+    "   0x[\\dabcdefABCDEF]+ <(.+?)>:"
+    "End of assembler dump\\." 
+}
+
+set test "x/i foo_low"
+gdb_test_multiple $test $test {
+    -re "   ($hex) <foo.*?>.*${gdb_prompt}" {
+        set foo_low_addr $expect_out(1,string)
+	pass $test
+    }
+}
+
+set test "x/i foo"
+gdb_test_multiple $test $test {
+    -re "   ($hex) <foo.*?>.*${gdb_prompt}" {
+        set foo_addr $expect_out(1,string)
+	pass $test
+    }
+}
+
+gdb_assert {$foo_low_addr != $foo_addr} "foo and foo_low are at different addresses"
+
+# This more permissive RE for "break foo" will allow a breakpoint on
+# multiple locations to PASS.  */
+gdb_test "break foo" \
+    "Breakpoint.*at.*" \
+    "break foo (2nd time)"
+
+gdb_test "break baz" \
+    "Breakpoint.*at.* file .*$srcfile, line \\d+\\."
+
+gdb_test "continue" \
+    "Breakpoint \\d+, foo \\(\\).*" \
+    "Continue to foo"
+
+gdb_test_no_output "set variable e=1"
+
+# If GDB incorrectly places the foo breakpoint on multiple locations,
+# then GDB will (incorrectly) stop in foo_low instead of in baz.
+gdb_test "continue" \
+    "Breakpoint \\d+, (?:$hex in )?baz \\(\\).*" \
+    "Continue to baz"
+
+clean_restart ${testfile}
+if ![runto_main] {
+    return -1
+}
+
+with_test_prefix "step-test-3" {
+    gdb_test "step" \
+	     "foo \\(\\).*bar \\(\\);.*foo bar call.*" \
+	     "step into foo from main"
+
+    gdb_test "step" \
+	     "bar \\(\\).*\}.* bar end.*" \
+	     "step into bar from foo"
+
+    gdb_test "step" \
+	     "foo(_label2)? \\(\\).*foo_low \\(\\);.*foo foo_low call.*" \
+	     "step out of bar to foo"
+
+    # The tests in the "enable_foo_low_stepping" work with some versions
+    # of gcc, though it's not clear to me that they should.  This example,
+    # which causes foo_low to be considered as part of foo via use of
+    # DW_AT_ranges.  Real code that I've looked at uses a branch instruction
+    # to cause code in the "cold" range to be executed.  If a subroutine
+    # call were used, it would be considered to be a separate subprogram
+    # and the issues that I see wouldn't be encountered.
+    #
+    # For the moment though, I've left these tests in place, but disabled,
+    # in the event that we decide that making such a subroutine call is
+    # a reasonable thing to do that should also be supported by GDB.
+
+    set enable_foo_low_stepping false
+
+    if { $enable_foo_low_stepping } {
+	gdb_test_no_output "set variable e=1"
+
+	set test "step into foo_low from foo"
+	gdb_test_multiple "step" $test {
+	    -re "foo(_low)? \\(\\).*\{.*foo_low prologue.*${gdb_prompt}" {
+		pass $test
+		gdb_test "step" \
+			 "foo \\(\\).*baz \\(\\);.*foo_low baz call.*" \
+			 "step to baz call in foo_low"
+
+	    }
+	    -re "foo(_low)? \\(\\).*baz \\(\\);.*foo_low baz call.*${gdb_prompt}" {
+		pass $test
+	    }
+	}
+
+	gdb_test "step" \
+		 "baz \\(\\).*\}.*baz end.*" \
+		 "step into baz from foo_low"
+
+	gdb_test "step" \
+		 "foo(?:_low(?:_label2)?)? \\(\\).*\}.*foo_low end.*" \
+		 "step out of baz to foo_low"
+
+	gdb_test "step" \
+		 "foo(?:_label3)? \\(\\).*\}.*foo end.*" \
+		 "step out of foo_low to foo"
+    } else {
+	gdb_test "next" \
+		 ".*foo end.*" \
+		 "next over foo_low call"
+    }
+
+    gdb_test "step" \
+	     "main(?:_label2)? \\(\\).*" \
+	     "step out of foo to main"
+}