[compiler-rt][XRay] Implement __xray_unpatch() and __xray_remove_handler()

Summary:
We also add one test (and the XRay testing infrastructure) to exercise
the patching and unpatching code. This uses the XRay API exported
through the headers as well, installing a custom log handler.

Depends on D23101 for the updated emitted code alignment for the
return/entry sleds.

Reviewers: rSerge, echristo, rnk

Subscribers: tberghammer, danalbert, srhines, mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D23154

llvm-svn: 277971

1 files changed, 47 insertions, 0 deletions

diff --git a/compiler-rt/test/xray/TestCases/Linux/patching-unpatching.cc b/compiler-rt/test/xray/TestCases/Linux/patching-unpatching.cc
new file mode 100644
index 00000000000..05478a48805
--- /dev/null
+++ b/compiler-rt/test/xray/TestCases/Linux/patching-unpatching.cc
@@ -0,0 +1,47 @@
+// Check that we can patch and un-patch on demand, and that logging gets invoked
+// appropriately.
+//
+// RUN: %clangxx_xray -fxray-instrument -std=c++11 %s -o %t
+// RUN: XRAY_OPTIONS="patch_premain=false" %run %t 2>&1 | FileCheck %s
+
+#include "xray/xray_interface.h"
+
+#include <cstdio>
+
+bool called = false;
+
+void test_handler(int32_t fid, XRayEntryType type) {
+  printf("called: %d, type=%d\n", fid, static_cast<int32_t>(type));
+  called = true;
+}
+
+[[clang::xray_always_instrument]] void always_instrument() {
+  printf("always instrumented called\n");
+}
+
+int main() {
+  __xray_set_handler(test_handler);
+  always_instrument();
+  // CHECK: always instrumented called
+  auto status = __xray_patch();
+  printf("patching status: %d\n", static_cast<int32_t>(status));
+  // CHECK-NEXT: patching status: 1
+  always_instrument();
+  // CHECK-NEXT: called: {{.*}}, type=0
+  // CHECK-NEXT: always instrumented called
+  // CHECK-NEXT: called: {{.*}}, type=1
+  status = __xray_unpatch();
+  printf("patching status: %d\n", static_cast<int32_t>(status));
+  // CHECK-NEXT: patching status: 1
+  always_instrument();
+  // CHECK-NEXT: always instrumented called
+  status = __xray_patch();
+  printf("patching status: %d\n", static_cast<int32_t>(status));
+  // CHECK-NEXT: patching status: 1
+  __xray_remove_handler();
+  always_instrument();
+  // CHECK-NEXT: always instrumented called
+  status = __xray_unpatch();
+  printf("patching status: %d\n", static_cast<int32_t>(status));
+  // CHECK-NEXT: patching status: 1
+}