Recommit r354328, r354329 "[obj2yaml][yaml2obj] - Add support of parsing/dumping of the .gnu.version_r section."

Fix:
Replace
assert(!IO.getContext() && "The IO context is initialized already");
with
assert(IO.getContext() && "The IO context is not initialized");
(this was introduced in r354329, where I tried to quickfix the darwin BB
and seems copypasted the assert from the wrong place).

Original commit message:

The section is described here:
https://refspecs.linuxfoundation.org/LSB_1.3.0/gLSB/gLSB/symverrqmts.html

Patch just teaches obj2yaml/yaml2obj to dump and parse such sections.

We did the finalization of string tables very late,
and I had to move the logic to make it a bit earlier.
That was needed in this patch since .gnu.version_r adds strings to .dynstr.
This might also be useful for implementing other special sections.

Everything else changed in this patch seems to be straightforward.

Differential revision: https://reviews.llvm.org/D58119

llvm-svn: 354335

2 files changed, 142 insertions, 0 deletions

diff --git a/llvm/test/tools/obj2yaml/verneed-section.yaml b/llvm/test/tools/obj2yaml/verneed-section.yaml
new file mode 100644
index 00000000000..6ca7cb2d88e
--- /dev/null
+++ b/llvm/test/tools/obj2yaml/verneed-section.yaml
@@ -0,0 +1,69 @@
+# RUN: yaml2obj %s -o %t
+# RUN: obj2yaml %t | FileCheck %s
+
+## Check we are able to yamalize SHT_GNU_verneed section.
+
+# CHECK:      - Name:            .gnu.version_r
+# CHECK-NEXT:   Type:            SHT_GNU_verneed
+# CHECK-NEXT:   Flags:           [ SHF_ALLOC ]
+# CHECK-NEXT:   Address:         0x0000000000200250
+# CHECK-NEXT:   Link:            .dynstr
+# CHECK-NEXT:   AddressAlign:    0x0000000000000004
+# CHECK-NEXT:   Info:            0x0000000000000002
+# CHECK-NEXT:   Dependencies:
+# CHECK-NEXT:     - Version:         1
+# CHECK-NEXT:       File:            dso.so.0
+# CHECK-NEXT:       Entries:
+# CHECK-NEXT:         - Name:            v1
+# CHECK-NEXT:           Hash:            1937
+# CHECK-NEXT:           Flags:           10
+# CHECK-NEXT:           Other:           3
+# CHECK-NEXT:         - Name:            v2
+# CHECK-NEXT:           Hash:            1938
+# CHECK-NEXT:           Flags:           11
+# CHECK-NEXT:           Other:           4
+# CHECK-NEXT:     - Version:         1
+# CHECK-NEXT:       File:            dso.so.1
+# CHECK-NEXT:       Entries:
+# CHECK-NEXT:         - Name:            v3
+# CHECK-NEXT:           Hash:            1939
+# CHECK-NEXT:           Flags:           12
+# CHECK-NEXT:           Other:           2
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_EXEC
+  Machine:         EM_X86_64
+  Entry:           0x0000000000201000
+Sections:
+  - Name:            .gnu.version_r
+    Type:            SHT_GNU_verneed
+    Flags:           [ SHF_ALLOC ]
+    Address:         0x200250
+    Link:            .dynstr
+    AddressAlign:    4
+    Info:            2
+    Dependencies:
+      - Version:         1
+        File:            dso.so.0
+        Entries:
+          - Name:            v1
+            Hash:            1937
+            Flags:           10
+            Other:           3
+          - Name:            v2
+            Hash:            1938
+            Flags:           11
+            Other:           4
+      - Version:         1
+        File:            dso.so.1
+        Entries:
+          - Name:            v3
+            Hash:            1939
+            Flags:           12
+            Other:           2
+DynamicSymbols:
+  Global:
+    - Name:            f1
diff --git a/llvm/test/tools/yaml2obj/verneed-section.yaml b/llvm/test/tools/yaml2obj/verneed-section.yaml
new file mode 100644
index 00000000000..436e54ba089
--- /dev/null
+++ b/llvm/test/tools/yaml2obj/verneed-section.yaml
@@ -0,0 +1,73 @@
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-readelf -V %t | FileCheck %s
+
+# Check we are able to handle the SHT_GNU_verneed sections.
+
+# CHECK:      SHT_GNU_verneed {
+# CHECK-NEXT:   Dependency {
+# CHECK-NEXT:     Version: 1
+# CHECK-NEXT:     Count: 2
+# CHECK-NEXT:     FileName: dso.so.0
+# CHECK-NEXT:     Entry {
+# CHECK-NEXT:       Hash: 1937
+# CHECK-NEXT:       Flags: 0xA
+# CHECK-NEXT:       Index: 3
+# CHECK-NEXT:       Name: v1
+# CHECK-NEXT:     }
+# CHECK-NEXT:     Entry {
+# CHECK-NEXT:       Hash: 1938
+# CHECK-NEXT:       Flags: 0xB
+# CHECK-NEXT:       Index: 4
+# CHECK-NEXT:       Name: v2
+# CHECK-NEXT:     }
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Dependency {
+# CHECK-NEXT:     Version: 1
+# CHECK-NEXT:     Count: 1
+# CHECK-NEXT:     FileName: dso.so.1
+# CHECK-NEXT:     Entry {
+# CHECK-NEXT:       Hash: 1939
+# CHECK-NEXT:       Flags: 0xC
+# CHECK-NEXT:       Index: 2
+# CHECK-NEXT:       Name: v3
+# CHECK-NEXT:     }
+# CHECK-NEXT:   }
+# CHECK-NEXT: }
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_EXEC
+  Machine:         EM_X86_64
+  Entry:           0x0000000000201000
+Sections:
+  - Name:            .gnu.version_r
+    Type:            SHT_GNU_verneed
+    Flags:           [ SHF_ALLOC ]
+    Address:         0x0000000000200250
+    Link:            .dynstr
+    AddressAlign:    0x0000000000000004
+    Info:            0x0000000000000002
+    Dependencies:
+      - Version:         1
+        File:            dso.so.0
+        Entries:
+          - Name:            v1
+            Hash:            1937
+            Flags:           10
+            Other:           3
+          - Name:            v2
+            Hash:            1938
+            Flags:           11
+            Other:           4
+      - Version:         1
+        File:            dso.so.1
+        Entries:
+          - Name:            v3
+            Hash:            1939
+            Flags:           12
+            Other:           2
+DynamicSymbols:
+  Global:
+    - Name:            f1