Allow yaml2obj to order implicit sections for ELF

Summary:
This change allows yaml input to control the order of implicitly added sections
(`.symtab`, `.strtab`, `.shstrtab`). The order is controlled by adding a
placeholder section of the given name to the Sections field.

This change is to support changes in D39582, where it is desirable to control
the location of the `.dynsym` section.

Reviewers: compnerd, jakehehrlich

Reviewed By: jakehehrlich

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D39749

llvm-svn: 317622

1 files changed, 29 insertions, 0 deletions

diff --git a/llvm/test/tools/yaml2obj/section-ordering.yaml b/llvm/test/tools/yaml2obj/section-ordering.yaml
new file mode 100644
index 00000000000..885b28a2c09
--- /dev/null
+++ b/llvm/test/tools/yaml2obj/section-ordering.yaml
@@ -0,0 +1,29 @@
+# Ensures that implicitly added sections can be ordered within Sections.
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-readobj -sections %t | FileCheck %s
+
+!ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_EXEC
+  Machine:         EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+  - Name:            .symtab
+    Type:            SHT_SYMTAB
+  - Name:            .data
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_WRITE ]
+  - Name:            .shstrtab
+    Type:            SHT_STRTAB
+  - Name:            .strtab
+    Type:            SHT_STRTAB
+
+# CHECK: Name: .text
+# CHECK: Name: .symtab
+# CHECK: Name: .data
+# CHECK: Name: .shstrtab
+# CHECK: Name: .strtab