Re: [PATCH v2 1/2] gdb/testsuite: add .debug_frame support in DWARF assembler

[Simon Marchi <simark@simark.ca>]

Ping.

On 2026-03-18 16:27, simon.marchi@polymtl.ca wrote:
> From: Simon Marchi <simon.marchi@efficios.com>
> 
> Add support to the DWARF assembler for generating .debug_frame sections.
> My initial use case is to reproduce a crash happening when encountering
> an empty FDE, but I suppose that other use cases will pop up in the
> future.
> 
>  - Generate procs for the `DW_CFA_*` constants, similar to how the
>    DW_OP_* constants are handled.  These `DW_CFA_*` procs are expected
>    to be used in the CIE and FDE bodies, described below.
> 
>  - Add handlers for `DW_CFA_*` operations that take arguments.  I tried
>    to cover everything that is in DWARF 5.
> 
>  - Add the `frame` proc, used to generate one .debug_frame section.
> 
>  - Add the `_frame_CIE` proc (available as `CIE` in the context of the
>    frame proc), used to generate one Common Information Entry.
> 
>  - Add the `_frame_FDE` proc (available as `FDE` in the context of the
>    frame proc), used to generate one Frame Description Entry.
> 
> Due to the nature of the .debug_frame contents (it describes how
> specific machine registers get saved), I expect that most of
> the tests written using this will be arch-specific.  But  I think it
> will still be useful, as it will let us craft .debug_frame sections to
> look exactly how we want.
> 
> I included a test (gdb.dwarf2/debug-frame.exp), which is more like a
> proof that we can build something useful using this, and can serve as an
> example for whoever wants to write a test case using this in the future.
> 
> Change-Id: I048568ded53883abf52d70139e5cd3e7b4ac3841
> ---
>  gdb/testsuite/gdb.dwarf2/debug-frame.S   | 101 ++++++
>  gdb/testsuite/gdb.dwarf2/debug-frame.exp | 130 ++++++++
>  gdb/testsuite/lib/dwarf.exp              | 394 ++++++++++++++++++++++-
>  3 files changed, 624 insertions(+), 1 deletion(-)
>  create mode 100644 gdb/testsuite/gdb.dwarf2/debug-frame.S
>  create mode 100644 gdb/testsuite/gdb.dwarf2/debug-frame.exp
> 
> diff --git a/gdb/testsuite/gdb.dwarf2/debug-frame.S b/gdb/testsuite/gdb.dwarf2/debug-frame.S
> new file mode 100644
> index 000000000000..231e2dc23704
> --- /dev/null
> +++ b/gdb/testsuite/gdb.dwarf2/debug-frame.S
> @@ -0,0 +1,101 @@
> +/* Copyright 2026 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/>.  */
> +
> +/* Hand-written x86-64 assembly with no .cfi directives.  The .debug_frame
> +   section is supplied by the companion -dw.S file, generated by the DWARF
> +   assembler.
> +
> +   The call chain: main -> caller -> callee.
> +
> +   caller sets some known register values, and callee saves those registers in
> +   different way.  */
> +
> +	.text
> +
> +/* main */
> +	.globl main
> +	.type main, @function
> +main:
> +	pushq	%rbp
> +	.globl main_after_push_rbp
> +main_after_push_rbp:
> +	movq	%rsp, %rbp
> +	.globl main_after_set_rbp
> +main_after_set_rbp:
> +	call	caller
> +	xorl	%eax, %eax
> +	popq	%rbp
> +	ret
> +	.size main, . - main
> +	.globl main_end
> +main_end:
> +	.globl main_len
> +	.set main_len, main_end - main
> +
> +/* caller */
> +	.globl caller
> +	.type caller, @function
> +caller:
> +	pushq	%rbp
> +	.globl caller_after_push_rbp
> +caller_after_push_rbp:
> +	movq	%rsp, %rbp
> +	.globl caller_after_set_rbp
> +caller_after_set_rbp:
> +	movq	$0x11223344, %r12
> +	movq	$0x55667788, %r13
> +	.globl caller_call_callee
> +caller_call_callee:
> +	call	callee
> +	popq	%rbp
> +	ret
> +	.size caller, . - caller
> +	.globl caller_end
> +caller_end:
> +	.globl caller_len
> +	.set caller_len, caller_end - caller
> +
> +/* callee */
> +	.globl callee
> +	.type callee, @function
> +callee:
> +	pushq	%rbp
> +	.globl callee_after_push_rbp
> +callee_after_push_rbp:
> +	movq	%rsp, %rbp
> +	.globl callee_after_set_rbp
> +callee_after_set_rbp:
> +	/* Save r12 in the stack, then clobber it.  */
> +	pushq	%r12
> +	xorq	%r12, %r12
> +	/* Save r13 in rax, then clobber it.  */
> +	movq	%r13, %rax
> +	xorq	%r13, %r13
> +	/* Clobber r14.  This one is described with a DWARF expression.  */
> +	xorq	%r14, %r14
> +	.globl callee_body
> +callee_body:
> +	nop
> +	movq	%rax, %r13
> +	popq	%r12
> +	popq	%rbp
> +	ret
> +	.size callee, . - callee
> +	.globl callee_end
> +callee_end:
> +	.globl callee_len
> +	.set callee_len, callee_end - callee
> +
> +	.section	.note.GNU-stack,"",@progbits
> diff --git a/gdb/testsuite/gdb.dwarf2/debug-frame.exp b/gdb/testsuite/gdb.dwarf2/debug-frame.exp
> new file mode 100644
> index 000000000000..ddadab7566ef
> --- /dev/null
> +++ b/gdb/testsuite/gdb.dwarf2/debug-frame.exp
> @@ -0,0 +1,130 @@
> +# Copyright 2026 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 that GDB can unwind using a .debug_frame section generated by
> +# the DWARF assembler.
> +#
> +# This test is amd64-specific, but could be ported to other
> +# architectures if needed.
> +
> +load_lib dwarf.exp
> +
> +require dwarf2_support is_x86_64_m64_target
> +
> +standard_testfile .S -dw.S
> +
> +# AMD64 DWARF register numbers.
> +set rax 0
> +set rbp 6
> +set rsp 7
> +set r12 12
> +set r13 13
> +set r14 14
> +set rip 16
> +
> +foreach_with_prefix is_64 { false true } {
> +    set asm_file [standard_output_file ${testfile}-${is_64}-dw.S]
> +
> +    Dwarf::assemble $asm_file {
> +	frame {
> +	    declare_labels cie_label
> +
> +	    cie_label: CIE {
> +		return_address_register $::rip
> +		data_alignment_factor -8
> +		is_64 $::is_64
> +	    } {
> +		DW_CFA_def_cfa $::rsp 8
> +		DW_CFA_offset $::rip 1
> +	    }
> +
> +	    # FDE for main
> +	    FDE $cie_label main main_len {
> +		is_64 $::is_64
> +	    } {
> +		DW_CFA_set_loc main_after_push_rbp
> +		DW_CFA_def_cfa_offset 16
> +		DW_CFA_offset $::rbp 2
> +		DW_CFA_set_loc main_after_set_rbp
> +		DW_CFA_def_cfa_register $::rbp
> +	    }
> +
> +	    # FDE for caller
> +	    FDE $cie_label caller caller_len {
> +		is_64 $::is_64
> +	    } {
> +		DW_CFA_set_loc caller_after_push_rbp
> +		DW_CFA_def_cfa_offset 16
> +		DW_CFA_offset $::rbp 2
> +		DW_CFA_set_loc caller_after_set_rbp
> +		DW_CFA_def_cfa_register $::rbp
> +	    }
> +
> +	    # FDE for callee
> +	    FDE $cie_label callee callee_len {
> +		is_64 $::is_64
> +	    } {
> +		DW_CFA_set_loc callee_after_push_rbp
> +		DW_CFA_def_cfa_offset 16
> +		DW_CFA_offset $::rbp 2
> +		DW_CFA_set_loc callee_after_set_rbp
> +		DW_CFA_def_cfa_register $::rbp
> +
> +		DW_CFA_set_loc callee_body
> +		DW_CFA_offset $::r12 3
> +		DW_CFA_register $::r13 $::rax
> +
> +		# r14's value is computed by an arbitrary expression.
> +		DW_CFA_val_expression $::r14 {
> +		    DW_OP_constu 0x99aabbcc
> +		}
> +	    }
> +	}
> +    }
> +
> +    if { [prepare_for_testing "failed to prepare" ${testfile}-${is_64} \
> +	      [list $srcfile $asm_file] {nodebug}] } {
> +	continue
> +    }
> +
> +    # Stop in caller before the call, to capture rbp.
> +    if { ![runto caller_call_callee] } {
> +	continue
> +    }
> +
> +    set caller_rbp [get_hexadecimal_valueof "\$rbp" "UNKNOWN"]
> +
> +    # Stop inside callee.
> +    gdb_breakpoint callee_body
> +    gdb_continue_to_breakpoint "callee_body"
> +
> +    # Verify backtrace shows the full call chain.
> +    gdb_test "bt" "#0.*callee.*\r\n#1.*caller.*\r\n#2.*main.*"
> +
> +    # Select caller's frame and check saved registers.
> +    gdb_test "frame 1" "#1.*caller.*"
> +
> +    # r12 was saved on the stack by callee.
> +    gdb_test "p/x \$r12" "= 0x11223344"
> +
> +    # r13 was saved in rax by callee.
> +    gdb_test "p/x \$r13" "= 0x55667788"
> +
> +    # r14's value is computed by a DWARF expression.
> +    gdb_test "p/x \$r14" "= 0x99aabbcc"
> +
> +    # rbp should match what caller had.
> +    gdb_test "p/x \$rbp" "= ${caller_rbp}"
> +}
> diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
> index 9fa5c4e297da..e545019e065b 100644
> --- a/gdb/testsuite/lib/dwarf.exp
> +++ b/gdb/testsuite/lib/dwarf.exp
> @@ -602,6 +602,10 @@ namespace eval Dwarf {
>      variable _loc_addr_size
>      variable _loc_offset_size
>  
> +    # Variables used when generating a .debug_frame section.
> +    variable _frame_addr_size
> +    variable _frame_offset_size
> +
>      proc _process_one_constant {name value} {
>  	variable _constants
>  	variable _FORM
> @@ -618,7 +622,6 @@ namespace eval Dwarf {
>  	}
>  
>  	# We only try to shorten some very common things.
> -	# FIXME: CFA?
>  	switch -exact -- $prefix {
>  	    TAG {
>  		# Create two procedures for the tag.  These call
> @@ -667,6 +670,57 @@ namespace eval Dwarf {
>  		} $name $name $handler]
>  	    }
>  
> +	    CFA {
> +		# Create procs for DW_CFA_* instructions, used in
> +		# .debug_frame CIE/FDE bodies.
> +
> +		# DW_CFA_advance_loc, DW_CFA_offset and
> +		# DW_CFA_restore encode the operand in the low 6
> +		# bits of the opcode byte.  They need special
> +		# handling.
> +		switch -exact -- $name {
> +		    DW_CFA_advance_loc {
> +			proc DW_CFA_advance_loc {delta} {
> +			    _op .byte \
> +				"$Dwarf::_constants(DW_CFA_advance_loc) + $delta" \
> +				DW_CFA_advance_loc
> +			}
> +		    }
> +
> +		    DW_CFA_offset {
> +			proc DW_CFA_offset {register offset} {
> +			    _op .byte \
> +				"$Dwarf::_constants(DW_CFA_offset) + $register" \
> +				DW_CFA_offset
> +			    _op .uleb128 $offset "offset"
> +			}
> +		    }
> +
> +		    DW_CFA_restore {
> +			proc DW_CFA_restore {register} {
> +			    _op .byte \
> +				"$Dwarf::_constants(DW_CFA_restore) + $register" \
> +				DW_CFA_restore
> +			}
> +		    }
> +
> +		    default {
> +			# Standard CFA instruction: emit opcode
> +			# byte then delegate to handler.
> +			set handler _handle_default_CFA
> +			if {[llength [info procs _handle_$name]] > 0} {
> +			    set handler _handle_$name
> +			}
> +
> +			# tclint-disable-next-line command-args
> +			proc $name {args} [format {
> +			    _op .byte $Dwarf::_constants(%s) %s
> +			    %s {*}$args
> +			} $name $name $handler]
> +		    }
> +		}
> +	    }
> +
>  	    default {
>  		return
>  	    }
> @@ -1456,6 +1510,127 @@ namespace eval Dwarf {
>  	# error.
>      }
>  
> +    # Helper to emit a DWARF expression block (ULEB128 length followed
> +    # by the expression bytes) inside a .debug_frame CIE or FDE body.
> +    # BODY is a Tcl code containing DW_OP_* calls.
> +    proc _emit_cfa_expression {body} {
> +	set start [new_label "cfa_expr_start"]
> +	set end [new_label "cfa_expr_end"]
> +	_op .uleb128 "$end - $start" "expression length"
> +	define_label $start
> +
> +	# Pass 5 as the DWARF version, since we need to pass something, but it
> +	# doesn't matter.  The DWARF version is checked only for DW_OP_* ops
> +	# that don't make sense in CFI.
> +	_location $body 5 $Dwarf::_frame_addr_size $Dwarf::_frame_offset_size
> +	define_label $end
> +    }
> +
> +    #
> +    # Handlers for DW_CFA_* instructions.
> +    #
> +    # A handler is only needed if the instruction requires operands.
> +    # Generic code handles emitting the opcode byte itself, so a
> +    # handler should not do this.
> +    #
> +    # Handlers are found by name when processing the .def file.  If a
> +    # handler isn't found, the default (_handle_default_CFA) is used.
> +    #
> +
> +    proc _handle_default_CFA {} {
> +	# Do nothing; if arguments are passed, Tcl will cause an
> +	# error.
> +    }
> +
> +    proc _handle_DW_CFA_set_loc {address} {
> +	_op .${Dwarf::_frame_addr_size}byte $address "address"
> +    }
> +
> +    proc _handle_DW_CFA_advance_loc1 {delta} {
> +	_op .byte $delta "delta"
> +    }
> +
> +    proc _handle_DW_CFA_advance_loc2 {delta} {
> +	_op .2byte $delta "delta"
> +    }
> +
> +    proc _handle_DW_CFA_advance_loc4 {delta} {
> +	_op .4byte $delta "delta"
> +    }
> +
> +    proc _handle_DW_CFA_offset_extended {register offset} {
> +	_op .uleb128 $register "register"
> +	_op .uleb128 $offset "offset"
> +    }
> +
> +    proc _handle_DW_CFA_restore_extended {register} {
> +	_op .uleb128 $register "register"
> +    }
> +
> +    proc _handle_DW_CFA_undefined {register} {
> +	_op .uleb128 $register "register"
> +    }
> +
> +    proc _handle_DW_CFA_same_value {register} {
> +	_op .uleb128 $register "register"
> +    }
> +
> +    proc _handle_DW_CFA_register {register1 register2} {
> +	_op .uleb128 $register1 "register"
> +	_op .uleb128 $register2 "register"
> +    }
> +
> +    proc _handle_DW_CFA_def_cfa {register offset} {
> +	_op .uleb128 $register "register"
> +	_op .uleb128 $offset "offset"
> +    }
> +
> +    proc _handle_DW_CFA_def_cfa_register {register} {
> +	_op .uleb128 $register "register"
> +    }
> +
> +    proc _handle_DW_CFA_def_cfa_offset {offset} {
> +	_op .uleb128 $offset "offset"
> +    }
> +
> +    proc _handle_DW_CFA_def_cfa_expression {body} {
> +	_emit_cfa_expression $body
> +    }
> +
> +    proc _handle_DW_CFA_expression {register body} {
> +	_op .uleb128 $register "register"
> +	_emit_cfa_expression $body
> +    }
> +
> +    proc _handle_DW_CFA_offset_extended_sf {register offset} {
> +	_op .uleb128 $register "register"
> +	_op .sleb128 $offset "offset"
> +    }
> +
> +    proc _handle_DW_CFA_def_cfa_sf {register offset} {
> +	_op .uleb128 $register "register"
> +	_op .sleb128 $offset "offset"
> +    }
> +
> +    proc _handle_DW_CFA_def_cfa_offset_sf {offset} {
> +	_op .sleb128 $offset "offset"
> +    }
> +
> +    proc _handle_DW_CFA_val_offset {register offset} {
> +	_op .uleb128 $register "register"
> +	_op .uleb128 $offset "offset"
> +    }
> +
> +    proc _handle_DW_CFA_val_offset_sf {register offset} {
> +	_op .uleb128 $register "register"
> +	_op .sleb128 $offset "offset"
> +    }
> +
> +    proc _handle_DW_CFA_val_expression {register body} {
> +	_op .uleb128 $register "register"
> +	_emit_cfa_expression $body
> +    }
> +
>      # This is a miniature assembler for location expressions.  It is
>      # suitable for use in the attributes to a DIE.
>      #
> @@ -3554,6 +3729,223 @@ namespace eval Dwarf {
>  	debug_str_offsets_end:
>      }
>  
> +    # Emit a DWARF .debug_frame section.
> +    #
> +    # BODY is Tcl code that emits the CIEs and FDEs which make up the
> +    # section.  It is evaluated in the caller's context.
> +    #
> +    # Within BODY, the following commands are available:
> +    #
> +    #   CIE options body
> +    #     -- emit a Common Information Entry.  See _frame_CIE for details.
> +    #
> +    #   FDE cie_label initial_location address_range body
> +    #     -- emit a Frame Description Entry.  See _frame_FDE for details.
> +    proc frame { body } {
> +	_section .debug_frame
> +
> +	with_override Dwarf::CIE Dwarf::_frame_CIE {
> +	    with_override Dwarf::FDE Dwarf::_frame_FDE {
> +		uplevel $Dwarf::_level $body
> +	    }
> +	}
> +    }
> +
> +    # Available as proc CIE when in the body of proc debug_frame.
> +    #
> +    # OPTIONS is a list of option-name/option-value pairs.  Supported
> +    # options are (default values are shown in parentheses):
> +    #
> +    #   is_64 (false)
> +    #     -- if true, emit a 64-bit CIE.
> +    #
> +    #   cie_id (default)
> +    #     -- the CIE id value.  When "default", uses 0xffffffff for
> +    #        32-bit and 0xffffffffffffffff for 64-bit.  Should typically not be
> +    #        used unless trying to craft an invalid CIE.
> +    #
> +    #   version (4)
> +    #     -- the CIE version number.  Note that this is version independent
> +    #        from the DWARF version.  DWARF 4 and 5 both use .debug_frame
> +    #        version 4.
> +    #
> +    #   augmentation ("")
> +    #     -- the augmentation string.
> +    #
> +    #   addr_size (default)
> +    #     -- the address size in bytes.  When "default", use 8 for 64-bit
> +    #        targets and 4 for 32-bit targets.
> +    #
> +    #   segment_selector_size (0)
> +    #     -- the segment selector size in bytes.
> +    #
> +    #   code_alignment_factor (1)
> +    #     -- the code alignment factor.
> +    #
> +    #   data_alignment_factor (1)
> +    #     -- the data alignment factor.
> +    #
> +    #   return_address_register (0)
> +    #     -- the number of the "column" containing the return address.
> +    #
> +    # BODY is Tcl code that emits the CIE's initial instructions using
> +    # DW_CFA_* operations.  It is evaluated in the caller's context.
> +    proc _frame_CIE {options body} {
> +	parse_options {
> +	    { is_64 false }
> +	    { cie_id default }
> +	    { version 4 }
> +	    { augmentation "" }
> +	    { addr_size default }
> +	    { segment_selector_size 0 }
> +	    { code_alignment_factor 1 }
> +	    { data_alignment_factor 1 }
> +	    { return_address_register 0 }
> +	}
> +
> +	if { $is_64 } {
> +	    set Dwarf::_frame_offset_size 8
> +	} else {
> +	    set Dwarf::_frame_offset_size 4
> +	}
> +
> +	if { $cie_id == "default" } {
> +	    if { $is_64 } {
> +		set cie_id 0xffffffffffffffff
> +	    } else {
> +		set cie_id 0xffffffff
> +	    }
> +	}
> +
> +	if {$addr_size == "default"} {
> +	    if {[is_64_target]} {
> +		set Dwarf::_frame_addr_size 8
> +	    } else {
> +		set Dwarf::_frame_addr_size 4
> +	    }
> +	} else {
> +	    set Dwarf::_frame_addr_size $addr_size
> +	}
> +
> +	declare_labels cie_post_length cie_end
> +
> +	# Length.
> +	if { $is_64 } {
> +	    _op .4byte 0xffffffff "length 1/2"
> +	    _op .8byte "$cie_end - $cie_post_length" "length 2/2"
> +	} else {
> +	    _op .4byte "$cie_end - $cie_post_length" "length"
> +	}
> +
> +	define_label $cie_post_length
> +
> +	# CIE_id
> +	_op .${Dwarf::_frame_offset_size}byte $cie_id "CIE_id"
> +
> +	# Version.
> +	_op .byte $version "version"
> +
> +	# Augmentation string.
> +	_op .ascii [_quote $augmentation] "augmentation"
> +
> +	# Address size.
> +	_op .byte $Dwarf::_frame_addr_size "address_size"
> +
> +	# Segment selector size.
> +	_op .byte 0 "segment_size"
> +
> +	# Code alignment factor.
> +	_op .uleb128 $code_alignment_factor "code_alignment_factor"
> +
> +	# Data alignment factor.
> +	_op .sleb128 $data_alignment_factor "data_alignment_factor"
> +
> +	# Return address register.
> +	_op .uleb128 $return_address_register "return_address_register"
> +
> +	# Initial instructions.
> +	uplevel $Dwarf::_level $body
> +
> +	# Padding up to the address size.  Fill with DW_CFA_nop (zeroes).
> +	_op .align $Dwarf::_frame_addr_size "padding"
> +
> +	define_label $cie_end
> +    }
> +
> +    # Available as proc FDE when in the body of proc debug_frame.
> +    #
> +    # CIE_LABEL is the label of the CIE this FDE refers to.
> +    #
> +    # INITIAL_LOCATION is the address of the first instruction covered
> +    # by this FDE.
> +    #
> +    # ADDRESS_RANGE is the number of bytes of instructions covered by
> +    # this FDE.
> +    #
> +    # OPTIONS is a list of option-name/option-value pairs.  Supported
> +    # options are (default values are shown in parentheses):
> +    #
> +    #   is_64 (false)
> +    #     -- if true, emit a 64-bit CIE.
> +    #
> +    #   addr_size (default)
> +    #     -- the address size in bytes.  When "default", use 8 for 64-bit
> +    #        targets and 4 for 32-bit targets.
> +    #
> +    # BODY is Tcl code that emits the FDE's call frame instructions using
> +    # DW_CFA_* operations.  It is evaluated in the caller's context.
> +    proc _frame_FDE { cie_label initial_location address_range options
> +		      body } {
> +	parse_options {
> +	    { is_64 false }
> +	    { addr_size default }
> +	}
> +
> +	if { $is_64 } {
> +	    set Dwarf::_frame_offset_size 8
> +	} else {
> +	    set Dwarf::_frame_offset_size 4
> +	}
> +
> +	if {$addr_size == "default"} {
> +	    if {[is_64_target]} {
> +		set Dwarf::_frame_addr_size 8
> +	    } else {
> +		set Dwarf::_frame_addr_size 4
> +	    }
> +	} else {
> +	    set Dwarf::_frame_addr_size $addr_size
> +	}
> +
> +	declare_labels fde_post_length fde_end
> +
> +	# Length.
> +	if { $is_64 } {
> +	    _op .4byte 0xffffffff "length 1/2"
> +	    _op .8byte "$fde_end - $fde_post_length" "length 2/2"
> +	} else {
> +	    _op .4byte "$fde_end - $fde_post_length" "length"
> +	}
> +	define_label $fde_post_length
> +
> +	# CIE pointer, offset of the CIE into the .debug_frame section.
> +	_op .${Dwarf::_frame_offset_size}byte $cie_label "CIE pointer"
> +
> +	# Initial location.
> +	_op .${Dwarf::_frame_addr_size}byte $initial_location "initial_location"
> +
> +	# Address range.
> +	_op .${Dwarf::_frame_addr_size}byte $address_range "address_range"
> +
> +	# Instructions.
> +	uplevel $Dwarf::_level $body
> +
> +	# Padding up to the address size.  Fill with DW_CFA_nop (zeroes).
> +	_op .align $Dwarf::_frame_addr_size "padding"
> +
> +	define_label $fde_end
> +    }
> +
>      # The top-level interface to the DWARF assembler.
>      # OPTIONS is a list with an even number of elements containing
>      # option-name and option-value pairs.
> 
> base-commit: bd40fc073ae0c30f8ad40623e9f40da1be09b0e5