[profile][test] Add -fuse-ld=bfd to make instrprof-lto-pgogen.c robust

Otherwise if 'ld' is an older system LLD (FreeBSD; or if someone adds 'ld' to
point to an LLD from a different installation) which does not support the
current ModuleSummaryIndex::BitCodeSummaryVersion, the test will fail.

Add lit feature 'binutils_lto'. GNU ld is more common than GNU gold, so
we can just require 'is_binutils_lto_supported' to additionally support GNU ld.

Reviewed By: myhsu

Differential Revision: https://reviews.llvm.org/D84133

compiler-rt/cmake/config-ix.cmake

@@ -610,7 +610,8 @@ else()
   set(CAN_SYMBOLIZE 1)
 endif()
 
-find_program(GOLD_EXECUTABLE NAMES ${LLVM_DEFAULT_TARGET_TRIPLE}-ld.gold ld.gold ${LLVM_DEFAULT_TARGET_TRIPLE}-ld ld DOC "The gold linker")
+find_program(GNU_LD_EXECUTABLE NAMES ${LLVM_DEFAULT_TARGET_TRIPLE}-ld.bfd ld.bfd DOC "GNU ld")
+find_program(GOLD_EXECUTABLE NAMES ${LLVM_DEFAULT_TARGET_TRIPLE}-ld.gold ld.gold DOC "GNU gold")
 
 if(COMPILER_RT_SUPPORTED_ARCH)
   list(REMOVE_DUPLICATES COMPILER_RT_SUPPORTED_ARCH)

compiler-rt/test/lit.common.cfg.py

@@ -413,19 +413,18 @@ def get_apple_min_deploy_target_flag_aligned_with_osx(version):
 def is_darwin_lto_supported():
   return os.path.exists(os.path.join(config.llvm_shlib_dir, 'libLTO.dylib'))
 
-def is_linux_lto_supported():
-  if config.use_lld:
-    return True
-
+def is_binutils_lto_supported():
   if not os.path.exists(os.path.join(config.llvm_shlib_dir, 'LLVMgold.so')):
     return False
 
-  ld_cmd = subprocess.Popen([config.gold_executable, '--help'], stdout = subprocess.PIPE, env={'LANG': 'C'})
-  ld_out = ld_cmd.stdout.read().decode()
-  ld_cmd.wait()
-
-  if not '-plugin' in ld_out:
-    return False
+  # We require both ld.bfd and ld.gold exist and support plugins. They are in
+  # the same repository 'binutils-gdb' and usually built together.
+  for exe in (config.gnu_ld_executable, config.gold_executable):
+    ld_cmd = subprocess.Popen([exe, '--help'], stdout=subprocess.PIPE, env={'LANG': 'C'})
+    ld_out = ld_cmd.stdout.read().decode()
+    ld_cmd.wait()
+    if not '-plugin' in ld_out:
+      return False
 
   return True
 
@@ -436,13 +435,20 @@ def is_windows_lto_supported():
   config.lto_supported = True
   config.lto_launch = ["env", "DYLD_LIBRARY_PATH=" + config.llvm_shlib_dir]
   config.lto_flags = []
-elif config.host_os in ['Linux', 'FreeBSD', 'NetBSD'] and is_linux_lto_supported():
-  config.lto_supported = True
-  config.lto_launch = []
+elif config.host_os in ['Linux', 'FreeBSD', 'NetBSD']:
+  config.lto_supported = False
   if config.use_lld:
-    config.lto_flags = ["-fuse-ld=lld"]
-  else:
-    config.lto_flags = ["-fuse-ld=gold"]
+    config.lto_supported = True
+  if is_binutils_lto_supported():
+    config.available_features.add('binutils_lto')
+    config.lto_supported = True
+
+  if config.lto_supported:
+    config.lto_launch = []
+    if config.use_lld:
+      config.lto_flags = ["-fuse-ld=lld"]
+    else:
+      config.lto_flags = ["-fuse-ld=gold"]
 elif config.host_os == 'Windows' and is_windows_lto_supported():
   config.lto_supported = True
   config.lto_launch = []

compiler-rt/test/lit.common.configured.in

@@ -19,6 +19,7 @@ set_default("compiler_rt_obj_root", "@COMPILER_RT_BINARY_DIR@")
 set_default("enable_per_target_runtime_dir", @LLVM_ENABLE_PER_TARGET_RUNTIME_DIR_PYBOOL@)
 set_default("llvm_tools_dir", "@LLVM_TOOLS_DIR@")
 set_default("llvm_shlib_dir", "@LLVM_LIBRARY_OUTPUT_INTDIR@")
+set_default("gnu_ld_executable", "@GNU_LD_EXECUTABLE@")
 set_default("gold_executable", "@GOLD_EXECUTABLE@")
 set_default("clang", "@COMPILER_RT_RESOLVED_TEST_COMPILER@")
 set_default("compiler_id", "@COMPILER_RT_TEST_COMPILER_ID@")

compiler-rt/test/profile/instrprof-lto-pgogen.c

@@ -1,13 +1,13 @@
-// REQUIRES: lto
-// XFAIL: msvc
+// REQUIRES: binutils_lto
 
-// RUN: %clang_pgogen=%t.profraw -flto %s -o %t
+// RUN: %clang_pgogen=%t.profraw -fuse-ld=bfd -flto %s -o %t
 // RUN: %run %t
 // RUN: llvm-profdata merge %t.profraw -o %t.profdata
 // RUN: llvm-profdata show %t.profdata | FileCheck %s
 
-// Testing a bug that happens when trying to generate IR
-// profile with BFD linker + LTO plugin
+/// Test that we work around https://sourceware.org/bugzilla/show_bug.cgi?id=26262
+/// (as of GNU ld 2.35) which happens when trying to generate IR profile with
+/// BFD linker + LLVMgold.so
 
 // CHECK: Instrumentation level: IR
 int main() { return 0; }