linker, assembler: Avoid intermediate bytevectors.

This reduces the amount of memory used during linking and reduces the
number of copies to be done between bytevectors.

* module/system/vm/linker.scm (<linker-object>): Remove 'bv' field and
add 'size' and 'writer'.
(make-linker-object): Adjust accordingly.
(string-table-size): New procedure.
(link-string-table!): Remove.
(string-table-writer): New procedure.
(allocate-segment): Adjust 'make-linker-object' call.
(find-shstrndx): Call the 'linker-object-writer' of O.
(add-elf-objects): Adjust 'make-linker-object' call.  Remove
'make-bytevector' allocations and move serialization to lazy 'writer'
procedures.  Define 'segments' and 'add-header-segment!'.  Return the
latter as the first value.
* module/system/vm/assembler.scm (make-object): Remove 'bv' parameter
and add 'size' and 'writer'.
(link-data): Remove 'make-bytevector' call and move serialization to
a lazy 'writer' procedure.
(link-text-object): Likewise.
(link-frame-maps): Likewise.
(link-dynamic-section): Likewise.
(link-shstrtab): Likewise.
(link-symtab): Likewise.
(link-arities): Likewise, and remove 'bytevector-append'.
(link-docstrs): Likewise.
(link-procprops): Likewise.
(link-debug): Likewise, and define 'copy-writer'.
* test-suite/tests/linker.test (link-elf-with-one-main-section): Adjust
accordingly.

1 files changed, 15 insertions, 6 deletions

diff --git a/test-suite/tests/linker.test b/test-suite/tests/linker.test
index e7ecc291e..ea54618b4 100644
--- a/test-suite/tests/linker.test
+++ b/test-suite/tests/linker.test
@@ -1,6 +1,6 @@
 ;;;; linker.test                               -*- scheme -*-
 ;;;;
-;;;; Copyright 2013, 2019 Free Software Foundation, Inc.
+;;;; Copyright 2013, 2019, 2023 Free Software Foundation, Inc.
 ;;;;
 ;;;; This library is free software; you can redistribute it and/or
 ;;;; modify it under the terms of the GNU Lesser General Public
@@ -25,23 +25,32 @@
 
 (define (link-elf-with-one-main-section name bytes)
   (let ((strtab (make-string-table)))
-    (define (make-object index name bv relocs . kwargs)
+    (define (make-object index name size writer relocs . kwargs)
       (let ((name-idx (string-table-intern! strtab (symbol->string name))))
         (make-linker-object (symbol->string name)
                             (apply make-elf-section
                                    #:index index
                                    #:name name-idx
-                                   #:size (bytevector-length bv)
+                                   #:size size
                                    kwargs)
-                            bv relocs
+                            size writer relocs
                             (list (make-linker-symbol name 0)))))
     (define (make-shstrtab)
       (string-table-intern! strtab ".shstrtab")
-      (make-object 2 '.shstrtab (link-string-table! strtab) '()
+      (make-object 2 '.shstrtab
+                   (string-table-size strtab)
+                   (string-table-writer strtab)
+                   '()
                    #:type SHT_STRTAB #:flags 0))
     (let* ((word-size (target-word-size))
            (endianness (target-endianness))
-           (sec (make-object 1 name bytes '()))
+           (sec (make-object 1 name
+                             (bytevector-length bytes)
+                             (lambda (bv offset)
+                               (bytevector-copy! bytes 0 bv offset
+                                                 (bytevector-length
+                                                  bytes)))
+                             '()))
            ;; This needs to be linked last, because linking other
            ;; sections adds entries to the string table.
            (shstrtab (make-shstrtab)))