[XRay][compiler-rt][x86_64] Align the stack before and after calling handlers

Summary:
This change fixes the XRay trampolines aside from the __xray_CustomEvent
trampoline to align the stack to 16-byte boundaries before calling the
handler. Before this change we've not been explicitly aligning the stack
to 16-byte boundaries, which makes it dangerous when calling handlers
that leave the stack in a state that isn't strictly 16-byte aligned
after calling the handlers.

We add a test that makes sure we can handle these cases appropriately
after the changes, and prevents us from regressing the state moving
forward.

Fixes http://llvm.org/PR35294.

Reviewers: pelikan, pcc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D40004

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@318261 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 57 insertions, 0 deletions

diff --git a/test/xray/TestCases/Linux/common-trampoline-alignment.cc b/test/xray/TestCases/Linux/common-trampoline-alignment.cc
new file mode 100644
index 000000000..5d1cc1e9b
--- /dev/null
+++ b/test/xray/TestCases/Linux/common-trampoline-alignment.cc
@@ -0,0 +1,57 @@
+// Make sure that we're aligning the stack properly to support handlers that
+// expect 16-byte alignment of the stack.
+//
+// RUN: %clangxx_xray -std=c++11 %s -o %t
+// RUN: XRAY_OPTIONS="patch_premain=false verbosity=1 xray_naive_log=false" \
+// RUN:     %run %t 2>&1
+// REQUIRES: x86_64-linux
+// REQUIRES: built-in-llvm-tree
+#include "xray/xray_interface.h"
+#include <stdio.h>
+#include <xmmintrin.h>
+
+[[clang::xray_never_instrument]] __attribute__((weak)) __m128 f(__m128 *i) {
+  return *i;
+}
+
+[[clang::xray_always_instrument]] __attribute__((noinline)) void noarg() {
+  __m128 v = {};
+  f(&v);
+}
+
+[[ clang::xray_always_instrument, clang::xray_log_args(1) ]]
+__attribute__((noinline)) void arg1(int) {
+  __m128 v = {};
+  f(&v);
+}
+
+[[clang::xray_always_instrument]] __attribute__((noinline))
+void no_alignment() {}
+
+[[clang::xray_never_instrument]] void noarg_handler(int32_t,
+                                                        XRayEntryType) {
+  printf("noarg handler called\n");
+  __m128 v = {};
+  f(&v);
+}
+
+[[clang::xray_never_instrument]] void arg1_handler(int32_t, XRayEntryType,
+                                                   uint64_t) {
+  printf("arg1 handler called\n");
+  __m128 v = {};
+  f(&v);
+}
+
+int main(int argc, char *argv[]) {
+  __xray_set_handler(noarg_handler);
+  __xray_set_handler_arg1(arg1_handler);
+  __xray_patch();
+  noarg();    // CHECK: noarg handler called
+  arg1(argc); // CHECK: arg1 handler called
+  no_alignment();
+  __xray_unpatch();
+  __xray_remove_handler();
+  __xray_remove_handler_arg1();
+  noarg();
+  arg1(argc);
+}