[binutils-gdb] Avoid unused space in .rela.dyn if sec was discarded

[liu & zhensong]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=fb266c9083b42d6287b2fe93a82ffe663d8f4640

commit fb266c9083b42d6287b2fe93a82ffe663d8f4640
Author: Jinyang He <hejinyang@loongson.cn>
Date:   Fri Sep 15 11:52:14 2023 +0800

    Avoid unused space in .rela.dyn if sec was discarded
    
    The relsec size is still increased although sec is discarded, which
    cause a lot of unused space allocated. Avoid size increased if sec
    was discarded.
    
    bfd/ChangeLog:
    
            * bfd/elfnn-loongarch.c: (allocate_dynrelocs): Do not increase
            sreloc size when discarded_section.
    
    ld/ChangeLog:
    
            * ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp: Add test.
            * ld/testsuite/ld-loongarch-elf/pie_discard.d: New test.
            * ld/testsuite/ld-loongarch-elf/pie_discard.s: New test.
            * ld/testsuite/ld-loongarch-elf/pie_discard.t: New test.

Diff:
---
 bfd/elfnn-loongarch.c                              |  2 ++
 ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp |  1 +
 ld/testsuite/ld-loongarch-elf/pie_discard.d        | 10 ++++++++++
 ld/testsuite/ld-loongarch-elf/pie_discard.s        |  9 +++++++++
 ld/testsuite/ld-loongarch-elf/pie_discard.t        |  9 +++++++++
 5 files changed, 31 insertions(+)

diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
index 1895699af06..1b5009e13b2 100644
--- a/bfd/elfnn-loongarch.c
+++ b/bfd/elfnn-loongarch.c
@@ -1368,6 +1368,8 @@ allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
 
   for (p = h->dyn_relocs; p != NULL; p = p->next)
     {
+      if (discarded_section (p->sec))
+	continue;
       asection *sreloc = elf_section_data (p->sec)->sreloc;
       sreloc->size += p->count * sizeof (ElfNN_External_Rela);
     }
diff --git a/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp b/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
index 2ad783fbae1..3a8629a07df 100644
--- a/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
+++ b/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
@@ -147,3 +147,4 @@ run_dump_test "underflow_b16"
 run_dump_test "underflow_b21"
 run_dump_test "underflow_b26"
 run_dump_test "underflow_pcrel20"
+run_dump_test "pie_discard"
diff --git a/ld/testsuite/ld-loongarch-elf/pie_discard.d b/ld/testsuite/ld-loongarch-elf/pie_discard.d
new file mode 100644
index 00000000000..7b8630912b5
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/pie_discard.d
@@ -0,0 +1,10 @@
+#source: pie_discard.s
+#ld: -pie -e 0 -T pie_discard.t
+#readelf: -rW
+
+#...
+Relocation section '\.rela\.dyn' .* 1 .*
+#...
+.*R_LARCH_RELATIVE.*
+#pass
+
diff --git a/ld/testsuite/ld-loongarch-elf/pie_discard.s b/ld/testsuite/ld-loongarch-elf/pie_discard.s
new file mode 100644
index 00000000000..82b88fc1e48
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/pie_discard.s
@@ -0,0 +1,9 @@
+  .text
+  .global sym
+sym: nop
+
+  .section .data,"aw"
+  .dword sym
+
+  .section .discard,"aw"
+  .dword sym
diff --git a/ld/testsuite/ld-loongarch-elf/pie_discard.t b/ld/testsuite/ld-loongarch-elf/pie_discard.t
new file mode 100644
index 00000000000..49e52cdb4b1
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/pie_discard.t
@@ -0,0 +1,9 @@
+SECTIONS
+{
+  . = SEGMENT_START("text-segment", 0) + SIZEOF_HEADERS;
+  .rela.dyn : { *(.rela.*) }
+  .text : { *(.text) }
+  . = DATA_SEGMENT_ALIGN (CONSTANT (MAXPAGESIZE), CONSTANT (COMMONPAGESIZE));
+  .data : { *(.data) }
+  /DISCARD/ : { *(.discard) }
+}