SanitizerCoverage: Support sanitizer guard section on darwin

[bogner]

Summary

MachO's sections need a segment as well as a section name, and the section start and end symbols are spelled differently than on ELF.

[kcc]

lib/Transforms/Instrumentation/SanitizerCoverage.cpp

141

no macros please.

[kubamracek]

Looks sane. Can you please re-upload the patch with more context?

[kubamracek]

Agree with @kcc, I don't think we need the prefix abstraction macro and we can just have strings with the full section/symbol name. E.g. in AddressSanitizer.cpp we have:

StringRef AddressSanitizerModule::getGlobalMetadataSection() const {
  switch (TargetTriple.getObjectFormat()) {
  case Triple::COFF:  return ".ASAN$GL";
  case Triple::ELF:   return "asan_globals";
  case Triple::MachO: return "__DATA,__asan_globals,regular";
  default: break;
  }
  llvm_unreachable("unsupported object format");
}

[bogner]

Get rid of the pointless string-abstraction macro. As Kostya and Kuba pointed out, it isn't really doing anything (and it's actually longer than just writing out the string).

Also note we'll need to un-xfail a test in compiler-rt when this is committed:

diff --git a/test/sanitizer_common/TestCases/sanitizer_coverage_trace_pc_guard.cc b/test/sanitizer_common/TestCases/sanitizer_coverage_trace_pc_guard.cc
index 1b787f143..e54993c5a 100644

• a/test/sanitizer_common/TestCases/sanitizer_coverage_trace_pc_guard.cc

+++ b/test/sanitizer_common/TestCases/sanitizer_coverage_trace_pc_guard.cc
@@ -1,7 +1,7 @@
Tests trace pc guard coverage collection.

REQUIRES: has_sancovcc,stable-runtime
- XFAIL: tsan,darwin,powerpc64,s390x
+ XFAIL: tsan,powerpc64,s390x

RUN: DIR=%t_workdir
RUN: rm -rf $DIR

[kcc]

LGTM

[bogner]

Committed in r293733, and the compiler-rt test update is r293734

lib/Transforms/Instrumentation/SanitizerCoverage.cpp

 static const char *const SanCovModuleCtorName = "sancov.module_ctor";
 static const uint64_t SanCtorAndDtorPriority = 2;
 
-static const char *const SanCovTracePCGuardSection = "__sancov_guards";
 static const char *const SanCovTracePCGuardName =
     "__sanitizer_cov_trace_pc_guard";
 static const char *const SanCovTracePCGuardInitName =

                                        cl::desc("Experimental 8-bit counters"),
                                        cl::Hidden, cl::init(false));
 
+static StringRef getSanCovTracePCGuardSection(const Module &M) {
+  return Triple(M.getTargetTriple()).isOSBinFormatMachO()
+             ? "__DATA,__sancov_guards"
+             : "__sancov_guards";
+}
+
+static StringRef getSanCovTracePCGuardSectionStart(const Module &M) {
+  return Triple(M.getTargetTriple()).isOSBinFormatMachO()
+             ? "\1section$start$__DATA$__sancov_guards"
+             : "__start___sancov_guards";
+}
+
+static StringRef getSanCovTracePCGuardSectionEnd(const Module &M) {
+  return Triple(M.getTargetTriple()).isOSBinFormatMachO()
+             ? "\1section$end$__DATA$__sancov_guards"
+             : "__stop___sancov_guards";
+}
+
 namespace {
 
 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {

   if (Options.TracePCGuard) {
     if (HasSancovGuardsSection) {
       Function *CtorFunc;
-      std::string SectionName(SanCovTracePCGuardSection);
-      GlobalVariable *Bounds[2];
-      const char *Prefix[2] = {"__start_", "__stop_"};
-      for (int i = 0; i < 2; i++) {
-        Bounds[i] = new GlobalVariable(M, Int32PtrTy, false,
-                                       GlobalVariable::ExternalLinkage, nullptr,
-                                       Prefix[i] + SectionName);
-        Bounds[i]->setVisibility(GlobalValue::HiddenVisibility);
-      }
+      GlobalVariable *SecStart = new GlobalVariable(
+          M, Int32PtrTy, false, GlobalVariable::ExternalLinkage, nullptr,
+          getSanCovTracePCGuardSectionStart(*CurModule));
+      SecStart->setVisibility(GlobalValue::HiddenVisibility);
+      GlobalVariable *SecEnd = new GlobalVariable(
+          M, Int32PtrTy, false, GlobalVariable::ExternalLinkage, nullptr,
+          getSanCovTracePCGuardSectionEnd(*CurModule));
+      SecEnd->setVisibility(GlobalValue::HiddenVisibility);
+
       std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
           M, SanCovModuleCtorName, SanCovTracePCGuardInitName,
           {Int32PtrTy, Int32PtrTy},
-          {IRB.CreatePointerCast(Bounds[0], Int32PtrTy),
-            IRB.CreatePointerCast(Bounds[1], Int32PtrTy)});
+          {IRB.CreatePointerCast(SecStart, Int32PtrTy),
+            IRB.CreatePointerCast(SecEnd, Int32PtrTy)});
 
       appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
     }

       Constant::getNullValue(ArrayOfInt32Ty), "__sancov_gen_");
   if (auto Comdat = F.getComdat())
     FunctionGuardArray->setComdat(Comdat);
-  FunctionGuardArray->setSection(SanCovTracePCGuardSection);
+  FunctionGuardArray->setSection(getSanCovTracePCGuardSection(*CurModule));
 }
 
 bool SanitizerCoverageModule::InjectCoverage(Function &F,

test/Instrumentation/SanitizerCoverage/tracing.ll

 ; RUN: opt < %s -sancov -sanitizer-coverage-level=3 -sanitizer-coverage-experimental-tracing  -S | FileCheck %s --check-prefix=CHECK3
 ; RUN: opt < %s -sancov -sanitizer-coverage-level=3 -sanitizer-coverage-trace-pc  -S | FileCheck %s --check-prefix=CHECK_PC
 ; RUN: opt < %s -sancov -sanitizer-coverage-level=3 -sanitizer-coverage-trace-pc-guard  -S | FileCheck %s --check-prefix=CHECK_PC_GUARD
+; RUN: opt < %s -sancov -sanitizer-coverage-level=3 -sanitizer-coverage-trace-pc-guard  -S -mtriple=x86_64-apple-macosx | FileCheck %s --check-prefix=CHECK_PC_GUARD_DARWIN
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
 target triple = "x86_64-unknown-linux-gnu"

 ; CHECK_PC_GUARD-NOT: call void @__sanitizer_cov_trace_pc
 ; CHECK_PC_GUARD: ret void
 ; CHECK_PC_GUARD: call void @__sanitizer_cov_trace_pc_guard_init(i32* bitcast (i32** @__start___sancov_guards to i32*), i32* bitcast (i32** @__stop___sancov_guards to i32*))
+
+; CHECK_PC_GUARD_DARWIN-LABEL: define void @foo
+; CHECK_PC_GUARD_DARWIN: call void @__sanitizer_cov_trace_pc_guard
+; CHECK_PC_GUARD_DARWIN: call void @__sanitizer_cov_trace_pc_guard
+; CHECK_PC_GUARD_DARWIN: call void @__sanitizer_cov_trace_pc_guard
+; CHECK_PC_GUARD_DARWIN-NOT: call void @__sanitizer_cov_trace_pc
+; CHECK_PC_GUARD_DARWIN: ret void
+; CHECK_PC_GUARD_DARWIN: call void @__sanitizer_cov_trace_pc_guard_init(i32* bitcast (i32** @"\01section$start$__DATA$__sancov_guards" to i32*), i32* bitcast (i32** @"\01section$end$__DATA$__sancov_guards" to i32*))