[test/gold] Add gold test subdirectory tests needing v1.12 (or higher)

[tejohnson]

Summary

As discussed in the review for D22677, added a subdirectory to
enable tests that require at least version 1.12 of gold.

Add an initial test requiring this version.

Another option would be to add this as a new available_feature in
test/lit.cfg and place the new tests directly in test/tools/gold/X86
with a REQUIRES tag.

[davidxl]

test/tools/gold/X86/v1.12/lit.local.cfg

18

probably just look at the minor version and use integer comparison? version 1.2 should be older version right?

[hjl.tools]

test/tools/gold/X86/v1.12/thinlto_emit_linked_objects.ll

13

"-m elf_x86_64" is needed for

target triple = "x86_64-unknown-linux-gnu" ​

[tejohnson]

test/tools/gold/X86/v1.12/lit.local.cfg

18

Ah yes, good catch. I should probably compare both separately, in case the major version ever increases. Will fix.

[tejohnson]

test/tools/gold/X86/v1.12/lit.local.cfg

18

Fixed.

test/tools/gold/X86/v1.12/thinlto_emit_linked_objects.ll

13

Fixed

[tejohnson]

• Address comments

[davidxl]

lgtm

[MatzeB]

This leads to the output of "ld -v" getting shown on my terminal every time I run "ninja check-llvm" on my macOS system.
(For some reason lit.site.cfg also has config.gold_executable pointing to /usr/bin/ld even though I am pretty sure that is not a gold linker on my machine).

test/tools/gold/X86/v1.12/Inputs/thinlto_emit_linked_objects.ll

+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @foo() {
+entry:
+  ret void
+}

test/tools/gold/X86/v1.12/lit.local.cfg

+import re
+import subprocess
+
+def is_gold_v1_12_linker_available():
+
+  if not config.gold_executable:
+    return False
+  try:
+    ld_cmd = subprocess.Popen([config.gold_executable, '-v'], stdout = subprocess.PIPE)
+    ld_out = ld_cmd.stdout.read().decode()
+    ld_cmd.wait()
+  except:
+    return False
+
+  match = re.search(r'GNU gold \(.*\) (\d+.\d+)$', ld_out)
+  if not match:
+    return False
+  version = float(match.group(1))
+  if version < 1.12:
+    return False
+
+  return True
+
+if not is_gold_v1_12_linker_available():
+  config.unsupported = True

test/tools/gold/X86/v1.12/thinlto_emit_linked_objects.ll

+; First generate bitcode with a module summary index for each file
+; RUN: opt -module-summary %s -o %t.o
+; RUN: opt -module-summary %p/Inputs/thinlto_emit_linked_objects.ll -o %t2.o
+
+; Next do the ThinLink step, specifying thinlto-index-only so that the gold
+; plugin exits after generating individual indexes. The objects the linker
+; decided to include in the link should be emitted into the file specified
+; after 'thinlto-index-only='. In this version of the test, only %t.o will
+; be included in the link, and not %t2.o since it is within
+; a library (--start-lib/--end-lib pair) and not strongly referenced.
+; Note that the support for detecting this is in gold v1.12.
+; RUN: %gold -plugin %llvmshlibdir/LLVMgold.so \
+; RUN:    --plugin-opt=thinlto \
+; RUN:    --plugin-opt=thinlto-index-only=%t3 \
+; RUN:    -o %t4 \
+; RUN:    %t.o \
+; RUN:    --start-lib %t2.o --end-lib
+
+; RUN: cat %t3 | FileCheck %s
+; CHECK: thinlto_emit_linked_objects.ll.tmp.o
+; CHECK-NOT: thinlto_emit_linked_objects.ll.tmp2.o
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @main() {
+entry:
+  ret i32 0
+}