tsan: don't instrument __attribute__((naked)) functions

Naked functions are required to not have compiler generated
prologues/epilogues, hence no instrumentation is needed for them.

Bugzilla: https://bugs.llvm.org/show_bug.cgi?id=45400

Differential Revision: https://reviews.llvm.org/D77477

diff --git a/llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
index 9b7edad..e8882e4 100644 (file)
--- a/llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
@@ -441,6 +441,11 @@ bool ThreadSanitizer::sanitizeFunction(Function &F,
   // the module constructor.
   if (F.getName() == kTsanModuleCtorName)
     return false;
+  // Naked functions can not have prologue/epilogue
+  // (__tsan_func_entry/__tsan_func_exit) generated, so don't instrument them at
+  // all.
+  if (F.hasFnAttribute(Attribute::Naked))
+    return false;
   initialize(*F.getParent());
   SmallVector<Instruction*, 8> AllLoadsAndStores;
   SmallVector<Instruction*, 8> LocalLoadsAndStores;

diff --git a/llvm/test/Instrumentation/ThreadSanitizer/tsan_basic.ll b/llvm/test/Instrumentation/ThreadSanitizer/tsan_basic.ll
index 953ab8e..100717a 100644 (file)
--- a/llvm/test/Instrumentation/ThreadSanitizer/tsan_basic.ll
+++ b/llvm/test/Instrumentation/ThreadSanitizer/tsan_basic.ll
@@ -78,5 +78,18 @@ define void @SwiftErrorCall(i8** swifterror) sanitize_thread {
   call void @SwiftError(i8** %0)
   ret void
 }
+
+; CHECK-LABEL: @NakedTest(i32* %a)
+; CHECK-NEXT:   call void @foo()
+; CHECK-NEXT:   %tmp1 = load i32, i32* %a, align 4
+; CHECK-NEXT:   ret i32 %tmp1
+define i32 @NakedTest(i32* %a) naked sanitize_thread {
+  call void @foo()
+  %tmp1 = load i32, i32* %a, align 4
+  ret i32 %tmp1
+}
+
+declare void @foo() nounwind
+
 ; CHECK: define internal void @tsan.module_ctor()
 ; CHECK: call void @__tsan_init()