From 42af6513589dbaf28b98a2d30d92cdd6a4884cc0 Mon Sep 17 00:00:00 2001
From: Dean Michael Berris <dberris@google.com>
Date: Tue, 9 May 2017 00:45:40 +0000
Subject: [PATCH] [XRay] Add __xray_customeevent(...) as a clang-supported
 builtin

Summary:
We define the `__xray_customeevent` builtin that gets translated to
IR calls to the correct intrinsic. The default implementation of this is
a no-op function. The codegen side of this follows the following logic:

- When `-fxray-instrument` is not provided in the driver, we elide all
calls to `__xray_customevent`.
- When `-fxray-instrument` is enabled and a function is marked as "never
instrumented", we elide all calls to `__xray_customevent` in that
function; if either marked as "always instrumented" or subject to
threshold-based instrumentation, we emit a call to the
`llvm.xray.customevent` intrinsic from LLVM for each
`__xray_customevent` occurrence in the function.

This change depends on D27503 (to land in LLVM first).

Reviewers: echristo, rsmith

Subscribers: mehdi_amini, pelikan, lrl, cfe-commits

Differential Revision: https://reviews.llvm.org/D30018

llvm-svn: 302492
---
 clang/include/clang/Basic/Builtins.def  |  3 +++
 clang/lib/CodeGen/CGBuiltin.cpp         | 26 ++++++++++++++++++++++++++
 clang/test/CodeGen/xray-customevent.cpp | 28 ++++++++++++++++++++++++++++
 3 files changed, 57 insertions(+)
 create mode 100644 clang/test/CodeGen/xray-customevent.cpp

diff --git a/clang/include/clang/Basic/Builtins.def b/clang/include/clang/Basic/Builtins.def
index 816ea15..a9ec172 100644
--- a/clang/include/clang/Basic/Builtins.def
+++ b/clang/include/clang/Basic/Builtins.def
@@ -1409,6 +1409,9 @@ LANGBUILTIN(to_private, "v*v*", "tn", OCLC20_LANG)
 BUILTIN(__builtin_os_log_format_buffer_size, "zcC*.", "p:0:nut")
 BUILTIN(__builtin_os_log_format, "v*v*cC*.", "p:0:nt")
 
+// Builtins for XRay
+BUILTIN(__xray_customevent, "vcC*z", "")
+
 #undef BUILTIN
 #undef LIBBUILTIN
 #undef LANGBUILTIN
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 2f05c0e..698bef2 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -2769,6 +2769,32 @@ RValue CodeGenFunction::EmitBuiltinExpr(const FunctionDecl *FD,
     return RValue::get(ConstantInt::get(ConvertType(E->getType()),
                                         Layout.size().getQuantity()));
   }
+
+  case Builtin::BI__xray_customevent: {
+    if (!ShouldXRayInstrumentFunction())
+      return RValue::getIgnored();
+    if (const auto *XRayAttr = CurFuncDecl->getAttr<XRayInstrumentAttr>()) {
+      if (XRayAttr->neverXRayInstrument())
+        return RValue::getIgnored();
+    }
+    Function *F = CGM.getIntrinsic(Intrinsic::xray_customevent);
+    auto FTy = F->getFunctionType();
+    auto Arg0 = E->getArg(0);
+    auto Arg0Val = EmitScalarExpr(Arg0);
+    auto Arg0Ty = Arg0->getType();
+    auto PTy0 = FTy->getParamType(0);
+    if (PTy0 != Arg0Val->getType()) {
+      if (Arg0Ty->isArrayType())
+        Arg0Val = EmitArrayToPointerDecay(Arg0).getPointer();
+      else
+        Arg0Val = Builder.CreatePointerCast(Arg0Val, PTy0);
+    }
+    auto Arg1 = EmitScalarExpr(E->getArg(1));
+    auto PTy1 = FTy->getParamType(1);
+    if (PTy1 != Arg1->getType())
+      Arg1 = Builder.CreateTruncOrBitCast(Arg1, PTy1);
+    return RValue::get(Builder.CreateCall(F, {Arg0Val, Arg1}));
+  }
   }
 
   // If this is an alias for a lib function (e.g. __builtin_sin), emit
diff --git a/clang/test/CodeGen/xray-customevent.cpp b/clang/test/CodeGen/xray-customevent.cpp
new file mode 100644
index 0000000..359d92d
--- /dev/null
+++ b/clang/test/CodeGen/xray-customevent.cpp
@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -fxray-instrument -x c++ -std=c++11 -triple x86_64-unknown-unknown -emit-llvm -o - %s | FileCheck %s
+
+// CHECK-LABEL: @_Z16alwaysInstrumentv
+[[clang::xray_always_instrument]] void alwaysInstrument() {
+  static constexpr char kPhase[] = "instrument";
+  __xray_customevent(kPhase, 10);
+  // CHECK: call void @llvm.xray.customevent(i8*{{.*}}, i32 10)
+}
+
+// CHECK-LABEL: @_Z15neverInstrumentv
+[[clang::xray_never_instrument]] void neverInstrument() {
+  static constexpr char kPhase[] = "never";
+  __xray_customevent(kPhase, 5);
+  // CHECK-NOT: call void @llvm.xray.customevent(i8*{{.*}}, i32 5)
+}
+
+// CHECK-LABEL: @_Z21conditionalInstrumenti
+[[clang::xray_always_instrument]] void conditionalInstrument(int v) {
+  static constexpr char kTrue[] = "true";
+  static constexpr char kUntrue[] = "untrue";
+  if (v % 2)
+    __xray_customevent(kTrue, 4);
+  else
+    __xray_customevent(kUntrue, 6);
+
+  // CHECK: call void @llvm.xray.customevent(i8*{{.*}}, i32 4)
+  // CHECK: call void @llvm.xray.customevent(i8*{{.*}}, i32 6)
+}
-- 
2.7.4