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Serialize source positions into .debug_line

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* module/system/vm/assembler.scm (link-debug): Generate a correct DWARF2
  line program.  Tests come next.
This commit is contained in:
Andy Wingo 2013-10-02 21:34:38 +02:00
parent 0a7340ac98
commit d56ab5a913
1 changed files with 95 additions and 12 deletions
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107
module/system/vm/assembler.scm
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@ -1518,6 +1518,14 @@ it will be added to the GC roots at runtime."
(put-u8 port (logior #x80 (logand val #x7f)))
(lp next))))))
(define (put-sleb128 port val)
(let lp ((val val))
(if (<= 0 (+ val 64) 128)
(put-u8 port (logand val #x7f))
(begin
(put-u8 port (logior #x80 (logand val #x7f)))
(lp (ash val -7))))))
(define (port-position port)
(seek port 0 SEEK_CUR))
@ -1579,13 +1587,26 @@ it will be added to the GC roots at runtime."
code))))
(define (write-sources)
;; Choose line base and line range values that will allow for an
;; address advance range of 16 words. The special opcode range is
;; from 10 to 255, so 246 values.
(define base -4)
(define range 15)
(let lp ((sources (asm-sources asm)) (out '()))
(match sources
(((pos . s) . sources)
(((pc . s) . sources)
(let ((file (assq-ref s 'filename))
(line (assq-ref s 'line))
(col (assq-ref s 'column)))
(lp sources (cons (list pos (intern-file file) line col) out))))
(lp sources
;; Guile line and column numbers are 0-indexed, but
;; they are 1-indexed for DWARF.
(cons (list pc
(if file (intern-file file) 0)
(if line (1+ line))
(if col (1+ col)))
out))))
(()
;; Compilation unit header for .debug_line. We write in
;; DWARF 2 format because more tools understand it than DWARF
@ -1597,8 +1618,8 @@ it will be added to the GC roots at runtime."
(put-u8 line-port 4) ; Minimum instruction length: 4 bytes.
(put-u8 line-port 1) ; Default is-stmt: true.
(put-s8 line-port 0) ; Line base. See the DWARF standard.
(put-u8 line-port 0) ; Line range. See the DWARF standard.
(put-s8 line-port base) ; Line base. See the DWARF standard.
(put-u8 line-port range) ; Line range. See the DWARF standard.
(put-u8 line-port 10) ; Opcode base: the first "special" opcode.
;; A table of the number of uleb128 arguments taken by each
@ -1639,14 +1660,76 @@ it will be added to the GC roots at runtime."
(put-u32 line-port (- offset 10))
(seek line-port offset SEEK_SET))
;; Now write sources.
;; ...
;; Now write the statement program.
(let ()
(define (extended-op opcode payload-len)
(put-u8 line-port 0) ; extended op
(put-uleb128 line-port (1+ payload-len)) ; payload-len + opcode
(put-uleb128 line-port opcode))
(define (set-address sym)
(define (add-reloc! kind)
(set! line-relocs
(cons (make-linker-reloc kind
(port-position line-port)
0
sym)
line-relocs)))
(match (asm-word-size asm)
(4
(extended-op 2 4)
(add-reloc! 'abs32/1)
(put-u32 line-port 0))
(8
(extended-op 2 8)
(add-reloc! 'abs64/1)
(put-u64 line-port 0))))
(define (end-sequence pc)
(let ((pc-inc (- (asm-pos asm) pc)))
(put-u8 line-port 2) ; advance-pc
(put-uleb128 line-port pc-inc))
(extended-op 1 0))
(define (advance-pc pc-inc line-inc)
(let ((spec (+ (- line-inc base) (* pc-inc range) 10)))
(cond
((or (< line-inc base) (>= line-inc (+ base range)))
(advance-line line-inc)
(advance-pc pc-inc 0))
((<= spec 255)
(put-u8 line-port spec))
((< spec 500)
(put-u8 line-port 8) ; const-advance-pc
(advance-pc (- pc-inc (floor/ (- 255 10) range))
line-inc))
(else
(put-u8 line-port 2) ; advance-pc
(put-uleb128 line-port pc-inc)
(advance-pc 0 line-inc)))))
(define (advance-line inc)
(put-u8 line-port 3)
(put-sleb128 line-port inc))
(define (set-file file)
(put-u8 line-port 4)
(put-uleb128 line-port file))
(define (set-column col)
(put-u8 line-port 5)
(put-uleb128 line-port col))
;; End sequence.
(put-u8 line-port 0) ; extended opcode:
(put-uleb128 line-port 1) ; one byte
(put-u8 line-port 1) ; end sequence.
))))
(set-address '.rtl-text)
(let lp ((in out) (pc 0) (file 1) (line 1) (col 0))
(match in
(() (end-sequence pc))
(((pc* file* line* col*) . in*)
(cond
((and (eqv? file file*) (eqv? line line*) (eqv? col col*))
(lp in* pc file line col))
(else
(unless (eqv? col col*)
(set-column col*))
(unless (eqv? file file*)
(set-file file*))
(advance-pc (- pc* pc) (- line* line))
(lp in* pc* file* line* col*)))))))))))
(define (compute-code attr val)
(match attr
@ -1687,7 +1770,7 @@ it will be added to the GC roots at runtime."
('data4 (put-u32 die-port code))
('data8 (put-u64 die-port code))
('uleb128 (put-uleb128 die-port code))
('sleb128 (error "not yet implemented"))
('sleb128 (put-sleb128 die-port code))
('addr
(match (asm-word-size asm)
(4