[llvm-readobj] - Rewrite gnuhash.test test to stop using precompiled objects.

[grimar]

Summary

This rewrites the test to use YAML and removes 4 precomipled object.

[grimar]

I've also added tests for llvm-readelf to document the behavior,
though I do not understand why it accepts --gnu-hash-table.
GNU readelf does not. Is it a bug?

[jhenderson]

LGTM.

In D73096#1831007, @grimar wrote:

I've also added tests for llvm-readelf to document the behavior,
though I do not understand why it accepts --gnu-hash-table.
GNU readelf does not. Is it a bug?

I wouldn't call it a bug. Rather, it's a feature. If you just want to dump the contents of the .gnu.hash section (and not the .hash section), you need this sort of switch. I think it's okay for us to have switches that are not accepted in GNU readelf, as long as the switch names are (relatively) unlikely to be used by GNU for something else in the future. I do however find it weird that the GNU and LLVM styles match.

llvm/test/tools/llvm-readobj/ELF/gnuhash.test

47

Are the dynamic symbols needed for the test?

[grimar]

llvm/test/tools/llvm-readobj/ELF/gnuhash.test

47

Yes, because the current implementation uses the information about number of them:

template <typename ELFT> void ELFDumper<ELFT>::printGnuHashTable() {
....
   Elf_Sym_Range Syms = dynamic_symbols();
   unsigned NumSyms = std::distance(Syms.begin(), Syms.end());
   if (!NumSyms)
     reportError(createError("No dynamic symbol section"), ObjF->getFileName());
   W.printHexList("Values", GnuHashTable->values(NumSyms));
 }

Such implementation implies, that if I add a one more - a garbage will be dumped:

Values: [0x8, 0x9, 0xA, 0xB, 0x6FFFFEF5]

I think it is a bug. We should either error out or don't print garbage values and warn this case instead.
I am going to fix this.

llvm/test/tools/llvm-readobj/ELF/gnuhash.test

-// Check dumping of the GNU Hash section
-// The input was generated using the following:
-// $ llvm-mc -filetype=obj -triple=i386-pc-linux      -o example-i386.o   example.s
-// $ llvm-mc -filetype=obj -triple=x86_64-pc-linux    -o example-x86_64.o example.s
-// $ llvm-mc -filetype=obj -triple=powerpc-pc-linux   -o example-ppc.o    example.s
-// $ llvm-mc -filetype=obj -triple=powerpc64-pc-linux -o example-ppc64.o  example.s
-// $ ld -shared -m elf_i386   -hash-style=gnu -o gnuhash.so.elf-i386   example-i386.o
-// $ ld -shared -m elf_x86_64 -hash-style=gnu -o gnuhash.so.elf-x86_64 example-x86_64.o
-// $ ld -shared -m elf32ppc   -hash-style=gnu -o gnuhash.so.elf-ppc    example-ppc.o
-// $ ld -shared -m elf64ppc   -hash-style=gnu -o gnuhash.so.elf-ppc64  example-ppc64.o
-// $ cat example.s
-// .globl foo
-// foo:
-
-RUN: llvm-readobj --gnu-hash-table %p/Inputs/gnuhash.so.elf-i386   | FileCheck %s -check-prefix I386
-RUN: llvm-readobj --gnu-hash-table %p/Inputs/gnuhash.so.elf-x86_64 | FileCheck %s -check-prefix X86_64
-RUN: llvm-readobj --gnu-hash-table %p/Inputs/gnuhash.so.elf-ppc    | FileCheck %s -check-prefix PPC
-RUN: llvm-readobj --gnu-hash-table %p/Inputs/gnuhash.so.elf-ppc64  | FileCheck %s -check-prefix PPC64
-
-I386:      Arch: i386
-I386:      GnuHashTable {
-I386-NEXT:   Num Buckets: 3
-I386-NEXT:   First Hashed Symbol Index: 1
-I386-NEXT:   Num Mask Words: 1
-I386-NEXT:   Shift Count: 5
-I386-NEXT:   Bloom Filter: [0x39004608]
-I386-NEXT:   Buckets: [1, 4, 0]
-I386-NEXT:   Values: [0xB887388, 0xECD54542, 0x7C92E3BB, 0x1C5871D9]
-I386-NEXT: }
-
-X86_64:      Arch: x86_64
-X86_64:      GnuHashTable {
-X86_64-NEXT:   Num Buckets: 3
-X86_64-NEXT:   First Hashed Symbol Index: 1
-X86_64-NEXT:   Num Mask Words: 1
-X86_64-NEXT:   Shift Count: 6
-X86_64-NEXT:   Bloom Filter: [0x800000001204288]
-X86_64-NEXT:   Buckets: [1, 4, 0]
-X86_64-NEXT:   Values: [0xB887388, 0xECD54542, 0x7C92E3BB, 0x1C5871D9]
-X86_64-NEXT: }
-
-PPC:      Arch: powerpc
-PPC:      GnuHashTable {
-PPC-NEXT:   Num Buckets: 3
-PPC-NEXT:   First Hashed Symbol Index: 1
-PPC-NEXT:   Num Mask Words: 1
-PPC-NEXT:   Shift Count: 5
-PPC-NEXT:   Bloom Filter: [0x3D00460A]
-PPC-NEXT:   Buckets: [1, 5, 0]
-PPC-NEXT:   Values: [0xEEBEC3A, 0xB887388, 0xECD54542, 0x7C92E3BB, 0x1C5871D9]
-PPC-NEXT: }
-
-PPC64:      Arch: powerpc64
-PPC64:      GnuHashTable {
-PPC64-NEXT:   Num Buckets: 3
-PPC64-NEXT:   First Hashed Symbol Index: 1
-PPC64-NEXT:   Num Mask Words: 1
-PPC64-NEXT:   Shift Count: 6
-PPC64-NEXT:   Bloom Filter: [0x800000001204288]
-PPC64-NEXT:   Buckets: [1, 4, 0]
-PPC64-NEXT:   Values: [0xB887388, 0xECD54542, 0x7C92E3BB, 0x1C5871D9]
-PPC64-NEXT: }
+## Check how the GNU Hash section is dumped with --gnu-hash-table.
 
+# RUN: yaml2obj --docnum=1 %s -o %t.x64
+# RUN: yaml2obj --docnum=2 %s -o %t.x32
+
+# RUN: llvm-readobj --gnu-hash-table %t.x64 | FileCheck %s
+# RUN: llvm-readelf --gnu-hash-table %t.x64 | FileCheck %s
+
+# RUN: llvm-readobj --gnu-hash-table %t.x32 | FileCheck %s
+# RUN: llvm-readelf --gnu-hash-table %t.x32 | FileCheck %s
+
+# CHECK:      GnuHashTable {
+# CHECK-NEXT:   Num Buckets: 3
+# CHECK-NEXT:   First Hashed Symbol Index: 1
+# CHECK-NEXT:   Num Mask Words: 2
+# CHECK-NEXT:   Shift Count: 2
+# CHECK-NEXT:   Bloom Filter: [0x3, 0x4]
+# CHECK-NEXT:   Buckets: [5, 6, 7]
+# CHECK-NEXT:   Values: [0x8, 0x9, 0xA, 0xB]
+# CHECK-NEXT: }
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name:  .gnu.hash
+    Type:  SHT_GNU_HASH
+    Flags: [ SHF_ALLOC ]
+    Header:
+      SymNdx: 0x1
+      Shift2: 0x2
+    BloomFilter: [0x3, 0x4]
+    HashBuckets: [0x5, 0x6, 0x7]
+    HashValues:  [0x8, 0x9, 0xA, 0xB]
+  - Name:  .dynamic
+    Type:  SHT_DYNAMIC
+    Flags: [ SHF_ALLOC ]
+    Link:  .dynstr
+    Entries:
+      - Tag:   DT_GNU_HASH
+        Value: 0x0
+      - Tag:   DT_NULL
+        Value: 0x0
+DynamicSymbols:
+  - Name:    aaa
+    Binding: STB_GLOBAL
+  - Name:    bbb
+    Binding: STB_GLOBAL
+  - Name:    ccc
+    Binding: STB_GLOBAL
+  - Name:    ddd
+    Binding: STB_GLOBAL
+ProgramHeaders:
+  - Type:  PT_LOAD
+    Flags: [ PF_R, PF_X ]
+    Sections:
+      - Section: .gnu.hash
+      - Section: .dynamic
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS32
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_386
+Sections:
+  - Name:  .gnu.hash
+    Type:  SHT_GNU_HASH
+    Flags: [ SHF_ALLOC ]
+    Header:
+      SymNdx: 0x1
+      Shift2: 0x2
+    BloomFilter: [0x3, 0x4]
+    HashBuckets: [0x5, 0x6, 0x7]
+    HashValues:  [0x8, 0x9, 0xA, 0xB]
+  - Name:  .dynamic
+    Type:  SHT_DYNAMIC
+    Flags: [ SHF_ALLOC ]
+    Link:  .dynstr
+    Entries:
+      - Tag:   DT_GNU_HASH
+        Value: 0x0
+      - Tag:   DT_NULL
+        Value: 0x0
+DynamicSymbols:
+  - Name:    aaa
+    Binding: STB_GLOBAL
+  - Name:    bbb
+    Binding: STB_GLOBAL
+  - Name:    ccc
+    Binding: STB_GLOBAL
+  - Name:    ddd
+    Binding: STB_GLOBAL
+ProgramHeaders:
+  - Type:  PT_LOAD
+    Flags: [ PF_R, PF_X ]
+    Sections:
+      - Section: .gnu.hash
+      - Section: .dynamic