From e159a0dd1a04a10fab2663dc5bc80a51b09e3636 Mon Sep 17 00:00:00 2001
From: Jonathan Metzman <metzman@chromium.org>
Date: Mon, 14 Jan 2019 21:02:02 +0000
Subject: [PATCH] [SanitizerCoverage][NFC] Use appendToUsed instead of include

Summary:
Use appendToUsed instead of include to ensure that
SanitizerCoverage's constructors are not stripped.

Also, use isOSBinFormatCOFF() to determine if target
binary format is COFF.

Reviewers: pcc

Reviewed By: pcc

Subscribers: hiraditya

Differential Revision: https://reviews.llvm.org/D56369

llvm-svn: 351118
---
 .../Instrumentation/SanitizerCoverage.cpp          | 23 +++++++---------------
 .../SanitizerCoverage/coff-used-ctor.ll            | 11 +++++++++++
 2 files changed, 18 insertions(+), 16 deletions(-)
 create mode 100644 llvm/test/Instrumentation/SanitizerCoverage/coff-used-ctor.ll

diff --git a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
index 7f683ad..729197f 100644
--- a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
+++ b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
@@ -264,7 +264,7 @@ SanitizerCoverageModule::CreateSecStartEnd(Module &M, const char *Section,
   SecEnd->setVisibility(GlobalValue::HiddenVisibility);
   IRBuilder<> IRB(M.getContext());
   Value *SecEndPtr = IRB.CreatePointerCast(SecEnd, Ty);
-  if (TargetTriple.getObjectFormat() != Triple::COFF)
+  if (!TargetTriple.isOSBinFormatCOFF())
     return std::make_pair(IRB.CreatePointerCast(SecStart, Ty), SecEndPtr);
 
   // Account for the fact that on windows-msvc __start_* symbols actually
@@ -293,24 +293,15 @@ Function *SanitizerCoverageModule::CreateInitCallsForSections(
     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
   }
 
-  if (TargetTriple.getObjectFormat() == Triple::COFF) {
+  if (TargetTriple.isOSBinFormatCOFF()) {
     // In COFF files, if the contructors are set as COMDAT (they are because
     // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced
     // functions and data) is used, the constructors get stripped. To prevent
-    // this, give the constructors weak ODR linkage and tell the linker to
-    // always include the sancov constructor. This way the linker can
-    // deduplicate the constructors but always leave one copy.
+    // this, give the constructors weak ODR linkage and ensure the linker knows
+    // to include the sancov constructor. This way the linker can deduplicate
+    // the constructors but always leave one copy.
     CtorFunc->setLinkage(GlobalValue::WeakODRLinkage);
-    SmallString<20> PartialIncDirective("/include:");
-    // Get constructor's mangled name in order to support i386.
-    SmallString<40> MangledName;
-    Mangler().getNameWithPrefix(MangledName, CtorFunc, true);
-    Twine IncDirective = PartialIncDirective + MangledName;
-    Metadata *Args[1] = {MDString::get(*C, IncDirective.str())};
-    MDNode *MetadataNode = MDNode::get(*C, Args);
-    NamedMDNode *NamedMetadata =
-        M.getOrInsertNamedMetadata("llvm.linker.options");
-    NamedMetadata->addOperand(MetadataNode);
+    appendToUsed(M, CtorFunc);
   }
   return CtorFunc;
 }
@@ -833,7 +824,7 @@ void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
 
 std::string
 SanitizerCoverageModule::getSectionName(const std::string &Section) const {
-  if (TargetTriple.getObjectFormat() == Triple::COFF) {
+  if (TargetTriple.isOSBinFormatCOFF()) {
     if (Section == SanCovCountersSectionName)
       return ".SCOV$CM";
     if (Section == SanCovPCsSectionName)
diff --git a/llvm/test/Instrumentation/SanitizerCoverage/coff-used-ctor.ll b/llvm/test/Instrumentation/SanitizerCoverage/coff-used-ctor.ll
new file mode 100644
index 0000000..fd12eed
--- /dev/null
+++ b/llvm/test/Instrumentation/SanitizerCoverage/coff-used-ctor.ll
@@ -0,0 +1,11 @@
+; Checks that sancov.module_ctor is marked used.
+; RUN: opt < %s -sancov -sanitizer-coverage-level=1 -sanitizer-coverage-inline-8bit-counters=1 -sanitizer-coverage-pc-table=1 -S | FileCheck %s
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc19.14.26433"
+
+define void @foo() {
+entry:
+  ret void
+}
+
+; CHECK: @llvm.used = appending global {{.*}} @sancov.module_ctor
\ No newline at end of file
-- 
2.7.4