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[XRay][clang] Introduce -fxray-always-emit-customevents Summary: The -fxray-always-emit-customevents flag instructs clang to always emit the LLVM IR for calls to the `__xray_customevent(...)` built-in function. The default behaviour currently respects whether the function has an `[[clang::xray_never_instrument]]` attribute, and thus not lower the appropriate IR code for the custom event built-in. This change allows users calling through to the `__xray_customevent(...)` built-in to always see those calls lowered to the corresponding LLVM IR to lay down instrumentation points for these custom event calls. Using this flag enables us to emit even just the user-provided custom events even while never instrumenting the start/end of the function where they appear. This is useful in cases where "phase markers" using __xray_customevent(...) can have very few instructions, must never be instrumented when entered/exited. Reviewers: rnk, dblaikie, kpw Subscribers: cfe-commits Differential Revision: https://reviews.llvm.org/D40601 llvm-svn: 319388
2017-11-30 08:04:54 +08:00
// RUN: %clang_cc1 -fxray-instrument -fxray-always-emit-customevents -x c++ \
// RUN: -std=c++11 -triple x86_64-unknown-unknown -emit-llvm -o - %s \
// RUN: | FileCheck %s
// CHECK-LABEL: @_Z15neverInstrumentv
[[clang::xray_never_instrument]] void neverInstrument() {
static constexpr char kPhase[] = "never";
__xray_customevent(kPhase, 5);
// CHECK: call void @llvm.xray.customevent(i8*{{.*}}, i32 5)
}