[ELF] Set SectionBase::partition in processSectionCommands

[MaskRay]

Summary

Fixes PR43461 (regression caused by D67504)

The partition field of a SECTIONS specified section is not set after
D67504. The 0 value affects findSection() which checks if the partition
field is 1.

So, Out::initArray = findSection(".init_array") is null, and
DT_INIT_ARRAYSZ is not set.

[andrewng]

Apart from the fix for the test, LGTM.

test/ELF/linkerscript/dynamic.s

10–11

Need to include "-T %t.script" to use the linker script.

[MaskRay]

Fix the test

[peter.smith]

LGTM too, one really trivial comment nit but just a readability suggestion so not that important.

ELF/LinkerScript.cpp

516

Really trivial nit, I think the "as what" would be better as "the same way as" Suggest "Set the partition field the same way OutputSection::recordSection() does."

[peter.smith]

Forgot to accept revision

[MaskRay]

Reword a comment

[MaskRay]

ELF/LinkerScript.cpp

516

Thanks a lot!

ELF/LinkerScript.cpp

if (auto *sec = dyn_cast<OutputSection>(base)) {
       // is given, input sections are aligned to that value, whether the
       // given value is larger or smaller than the original section alignment.
       if (sec->subalignExpr) {
         uint32_t subalign = sec->subalignExpr().getValue();
         for (InputSectionBase *s : v)
           s->alignment = subalign;
       }
 
+      // Set the partition field as what OutputSection::recordSection() does.
+      // Partitions cannot be used with the SECTIONS command, so this is always
+      // 1.
+      sec->partition = 1;
+
       sec->sectionIndex = i++;
     }
   }
 }
 
 void LinkerScript::processSymbolAssignments() {
   // Dot outside an output section still represents a relative address, whose
   // sh_shndx should not be SHN_UNDEF or SHN_ABS. Create a dummy aether section

test/ELF/linkerscript/dynamic.s

 # REQUIRES: x86
+
+## Test that DT_INIT_ARRAYSZ/DT_FINI_ARRAYSZ/DT_PREINIT_ARRAYSZ are computed
+## correctly, no matter their associated sections are orphans or not.
+
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t1.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/shared.s -o %t2.o
-# RUN: ld.lld -shared %t2.o -o %t2.so
+# RUN: ld.lld -shared %t2.o -soname=so -o %t2.so
 
-# RUN: echo "SECTIONS { }" > %t.script
-# RUN: ld.lld %t1.o %t2.so -o %t
+# RUN: echo "SECTIONS { .init_array : { *(.init_array) } }" > %t.script
+# RUN: ld.lld -T %t.script %t1.o %t2.so -o %t
 # RUN: llvm-readobj --dynamic-table %t | FileCheck %s
 
 # CHECK:      DynamicSection [
 # CHECK-NEXT:  Tag                 Type             Name/Value
 # CHECK:       0x0000000000000021  PREINIT_ARRAYSZ  9 (bytes)
 # CHECK:       0x000000000000001B  INIT_ARRAYSZ     8 (bytes)
 # CHECK:       0x000000000000001C  FINI_ARRAYSZ     10 (bytes)