From 18b6fb96120336cfcf8981483501ecf98c63f00c Mon Sep 17 00:00:00 2001
From: Evgeniy Stepanov <eugeni.stepanov@gmail.com>
Date: Tue, 27 May 2014 12:39:31 +0000
Subject: [PATCH] [asancov] Emit an initializer passing number of coverage code
 locations in each module.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209654 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../Instrumentation/AddressSanitizer.cpp       | 18 ++++++++++++++----
 .../AddressSanitizer/coverage.ll               | 12 ++++++++++++
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 0617215a7c0..95fca75392a 100644
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -80,6 +80,7 @@ static const char *const kAsanUnregisterGlobalsName =
 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
 static const char *const kAsanInitName = "__asan_init_v3";
+static const char *const kAsanCovModuleInitName = "__sanitizer_cov_module_init";
 static const char *const kAsanCovName = "__sanitizer_cov";
 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
@@ -408,6 +409,7 @@ class AddressSanitizerModule : public ModulePass {
   Function *AsanUnpoisonGlobals;
   Function *AsanRegisterGlobals;
   Function *AsanUnregisterGlobals;
+  Function *AsanCovModuleInit;
 };
 
 // Stack poisoning does not play well with exception handling.
@@ -990,6 +992,10 @@ void AddressSanitizerModule::initializeCallbacks(Module &M) {
       kAsanUnregisterGlobalsName,
       IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
   AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
+  AsanCovModuleInit = checkInterfaceFunction(M.getOrInsertFunction(
+      kAsanCovModuleInitName,
+      IRB.getVoidTy(), IntptrTy, NULL));
+  AsanCovModuleInit->setLinkage(Function::ExternalLinkage);
 }
 
 // This function replaces all global variables with new variables that have
@@ -1020,6 +1026,14 @@ bool AddressSanitizerModule::runOnModule(Module &M) {
       GlobalsToChange.push_back(G);
   }
 
+  Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
+  assert(CtorFunc);
+  IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
+
+  Function *CovFunc = M.getFunction(kAsanCovName);
+  int nCov = CovFunc ? CovFunc->getNumUses() : 0;
+  IRB.CreateCall(AsanCovModuleInit, ConstantInt::get(IntptrTy, nCov));
+
   size_t n = GlobalsToChange.size();
   if (n == 0) return false;
 
@@ -1036,10 +1050,6 @@ bool AddressSanitizerModule::runOnModule(Module &M) {
                                                IntptrTy, IntptrTy, NULL);
   SmallVector<Constant *, 16> Initializers(n);
 
-  Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
-  assert(CtorFunc);
-  IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
-
   bool HasDynamicallyInitializedGlobals = false;
 
   // We shouldn't merge same module names, as this string serves as unique
diff --git a/test/Instrumentation/AddressSanitizer/coverage.ll b/test/Instrumentation/AddressSanitizer/coverage.ll
index 7f397f453ff..5bc510316aa 100644
--- a/test/Instrumentation/AddressSanitizer/coverage.ll
+++ b/test/Instrumentation/AddressSanitizer/coverage.ll
@@ -16,6 +16,7 @@ entry:
   if.end:                                           ; preds = %entry, %if.then
   ret void
 }
+
 ; CHECK1-LABEL: define void @foo
 ; CHECK1: %0 = load atomic i8* @__asan_gen_cov_foo monotonic, align 1
 ; CHECK1: %1 = icmp eq i8 0, %0
@@ -24,9 +25,20 @@ entry:
 ; CHECK1-NOT: call void @__sanitizer_cov
 ; CHECK1: store atomic i8 1, i8* @__asan_gen_cov_foo monotonic, align 1
 
+; CHECK1-LABEL: define internal void @asan.module_ctor
+; CHECK1-NOT: ret
+; CHECK1: call void @__sanitizer_cov_module_init(i64 1)
+; CHECK1: ret
+
+
 ; CHECK2-LABEL: define void @foo
 ; CHECK2: call void @__sanitizer_cov
 ; CHECK2: call void @__sanitizer_cov
 ; CHECK2: call void @__sanitizer_cov
 ; CHECK2-NOT: call void @__sanitizer_cov
 ; CHECK2: ret void
+
+; CHECK2-LABEL: define internal void @asan.module_ctor
+; CHECK2-NOT: ret
+; CHECK2: call void @__sanitizer_cov_module_init(i64 3)
+; CHECK2: ret