[profile] Add test for dead_strip+live_support functionality

[vsk]

Summary

On Darwin, marking a section as "regular,live_support" means that a
symbol in the section should only be kept live if it has a reference to
something that is live. Otherwise, the linker is free to dead-strip it.

Add a test for dead_strip+live_support functionality for profile data.

Depends on D25456.

[mehdi_amini]

test/profile/instrprof-darwin-dead-strip.c

6

I've never looked at compiler-rt tests. We usually build and run these?

[davidxl]

test/profile/instrprof-darwin-dead-strip.c

6

compiler-rt tests are usually end-end tests with run step

[davidxl]

test/profile/instrprof-darwin-dead-strip.c

23

Also check other related sections are dead-stripped?

[vsk]

• Make the test more thorough per @davidxl's comment.

[davidxl]

lgtm

test/profile/instrprof-darwin-dead-strip.c

+// REQUIRES: osx-ld64-live_support
+// REQUIRES: lto
+
+// RUN: %clang_profgen=%t.profraw -fcoverage-mapping -mllvm -enable-name-compression=false -Wl,-dead_strip -o %t %s
+// RUN: %run %t
+// RUN: llvm-profdata merge -o %t.profdata %t.profraw
+// RUN: llvm-profdata show --all-functions %t.profdata | FileCheck %s -check-prefix=PROF
+// RUN: llvm-cov show %t -instr-profile %t.profdata | FileCheck %s -check-prefix=COV
+// RUN: nm %t | FileCheck %s -check-prefix=NM
+// RUN: otool -s __DATA __llvm_prf_names %t | FileCheck %s -check-prefix=PRF_NAMES
+// RUN: otool -s __DATA __llvm_prf_cnts %t | FileCheck %s -check-prefix=PRF_CNTS
+
+// RUN: %clang_lto_profgen=%t.lto.profraw -fcoverage-mapping -mllvm -enable-name-compression=false -Wl,-dead_strip -flto -o %t.lto %s
+// RUN: %run %t.lto
+// RUN: llvm-profdata merge -o %t.lto.profdata %t.lto.profraw
+// RUN: llvm-profdata show --all-functions %t.lto.profdata | FileCheck %s -check-prefix=PROF
+// RUN: llvm-cov show %t.lto -instr-profile %t.lto.profdata | FileCheck %s -check-prefix=COV
+// RUN: nm %t.lto | FileCheck %s -check-prefix=NM
+// RUN: otool -s __DATA __llvm_prf_names %t.lto | FileCheck %s -check-prefix=PRF_NAMES
+// RUN: otool -s __DATA __llvm_prf_cnts %t.lto | FileCheck %s -check-prefix=PRF_CNTS
+
+// Note: We expect foo() and some of the profiling data associated with it to
+// be dead-stripped.
+
+// COV: [[@LINE+1]]{{ *}}|{{ *}}0|void foo()
+void foo() {}
+
+// COV: [[@LINE+1]]{{ *}}|{{ *}}1|int main
+int main() { return 0; }
+
+// NM-NOT: foo
+
+// PROF: Counters:
+// PROF-NEXT:   main:
+// PROF-NEXT:     Hash:
+// PROF-NEXT:     Counters: 1
+// PROF-NEXT:     Function count: 1
+// PROF-NEXT: Functions shown: 1
+// PROF-NEXT: Total functions: 1
+// PROF-NEXT: Maximum function count: 1
+// PROF-NEXT: Maximum internal block count: 0
+
+// Note: We don't expect the names of dead-stripped functions to disappear from
+// __llvm_prf_names, because collectPGOFuncNameStrings() glues the names
+// together.
+
+// PRF_NAMES: Contents of (__DATA,__llvm_prf_names) section
+// PRF_NAMES-NEXT: {{.*}} 08 00 66 6f 6f 01 6d 61 69 6e{{ +$}}
+//                        |  |  f  o  o  #  m  a  i  n
+//                        |  |___________|
+//                        |              |
+//               UncompressedLen = 8     |
+//                                       |
+//                                CompressedLen = 0
+
+// Note: We expect the profile counters for dead-stripped functions to also be
+// dead-stripped.
+
+// PRF_CNTS: Contents of (__DATA,__llvm_prf_cnts) section
+// PRF_CNTS-NEXT: {{.*}} 00 00 00 00 00 00 00 00{{ +$}}

test/profile/lit.cfg

 # What to exclude.
 config.excludes = ['Inputs']
 
 # Clang flags.
 target_cflags=[get_required_attr(config, "target_cflags")]
 clang_cflags = target_cflags + extra_linkflags
 clang_cxxflags = config.cxx_mode_flags + clang_cflags
 
-def build_invocation(compile_flags):
-  return " " + " ".join([config.clang] + compile_flags) + " "
+def build_invocation(compile_flags, with_lto = False):
+  lto_flags = []
+  lto_prefix = []
+  if with_lto and config.lto_supported:
+    lto_flags += config.lto_flags
+    lto_prefix += config.lto_launch
+  return " " + " ".join(lto_prefix + [config.clang] + lto_flags + compile_flags) + " "
 
 # Add clang substitutions.
 config.substitutions.append( ("%clang ", build_invocation(clang_cflags)) )
 config.substitutions.append( ("%clangxx ", build_invocation(clang_cxxflags)) )
 config.substitutions.append( ("%clang_profgen ", build_invocation(clang_cflags) + " -fprofile-instr-generate ") )
 config.substitutions.append( ("%clang_profgen=", build_invocation(clang_cflags) + " -fprofile-instr-generate=") )
 config.substitutions.append( ("%clang_pgogen ", build_invocation(clang_cflags) + " -fprofile-generate ") )
 config.substitutions.append( ("%clang_pgogen=", build_invocation(clang_cflags) + " -fprofile-generate=") )
 
 config.substitutions.append( ("%clangxx_profgen ", build_invocation(clang_cxxflags) + " -fprofile-instr-generate ") )
 config.substitutions.append( ("%clangxx_profgen=", build_invocation(clang_cxxflags) + " -fprofile-instr-generate=") )
 config.substitutions.append( ("%clangxx_pgogen ", build_invocation(clang_cxxflags) + " -fprofile-generate ") )
 config.substitutions.append( ("%clangxx_pgogen=", build_invocation(clang_cxxflags) + " -fprofile-generate=") )
 
 config.substitutions.append( ("%clang_profgen_gcc=", build_invocation(clang_cflags) + " -fprofile-generate=") )
 config.substitutions.append( ("%clang_profuse_gcc=", build_invocation(clang_cflags) + " -fprofile-use=") )
 
 config.substitutions.append( ("%clang_profuse=", build_invocation(clang_cflags) + " -fprofile-instr-use=") )
 config.substitutions.append( ("%clangxx_profuse=", build_invocation(clang_cxxflags) + " -fprofile-instr-use=") )
 
+config.substitutions.append( ("%clang_lto_profgen=", build_invocation(clang_cflags, True) + " -fprofile-instr-generate=") )
+
 if config.host_os not in ['Darwin', 'FreeBSD', 'Linux']:
   config.unsupported = True
 
 if config.target_arch in ['armv7l']:
   config.unsupported = True