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[XRay][clang] Emit "never-instrument" attribute 

Summary:
Before this change, we only emit the XRay attributes in LLVM IR when the
-fxray-instrument flag is provided. This may cause issues with thinlto
when the final binary is being built/linked with -fxray-instrument, and
the constitutent LLVM IR gets re-lowered with xray instrumentation.

With this change, we can honour the "never-instrument "attributes
provided in the source code and preserve those in the IR. This way, even
in thinlto builds, we retain the attributes which say whether functions
should never be XRay instrumented.

This change addresses llvm.org/PR38922.

Reviewers: mboerger, eizan

Subscribers: mehdi_amini, dexonsmith, cfe-commits, llvm-commits

Differential Revision: https://reviews.llvm.org/D52015

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@342200 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dean Michael Berris 2018-09-14 01:59:12 +00:00
parent 7592787111
commit f544500eef
4 changed files with 55 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
lib/CodeGen/CodeGenFunction.cpp
View File

@ -901,21 +901,21 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
}
// Apply xray attributes to the function (as a string, for now)
bool InstrumentXray = ShouldXRayInstrumentFunction() &&
CGM.getCodeGenOpts().XRayInstrumentationBundle.has(
XRayInstrKind::Function);
if (D && InstrumentXray) {
if (D) {
if (const auto *XRayAttr = D->getAttr<XRayInstrumentAttr>()) {
if (XRayAttr->alwaysXRayInstrument())
Fn->addFnAttr("function-instrument", "xray-always");
if (XRayAttr->neverXRayInstrument())
Fn->addFnAttr("function-instrument", "xray-never");
if (const auto *LogArgs = D->getAttr<XRayLogArgsAttr>()) {
Fn->addFnAttr("xray-log-args",
llvm::utostr(LogArgs->getArgumentCount()));
if (CGM.getCodeGenOpts().XRayInstrumentationBundle.has(
XRayInstrKind::Function)) {
if (XRayAttr->alwaysXRayInstrument() && ShouldXRayInstrumentFunction())
Fn->addFnAttr("function-instrument", "xray-always");
if (XRayAttr->neverXRayInstrument())
Fn->addFnAttr("function-instrument", "xray-never");
if (const auto *LogArgs = D->getAttr<XRayLogArgsAttr>())
if (ShouldXRayInstrumentFunction())
Fn->addFnAttr("xray-log-args",
llvm::utostr(LogArgs->getArgumentCount()));
}
} else {
if (!CGM.imbueXRayAttrs(Fn, Loc))
if (ShouldXRayInstrumentFunction() && !CGM.imbueXRayAttrs(Fn, Loc))
Fn->addFnAttr(
"xray-instruction-threshold",
llvm::itostr(CGM.getCodeGenOpts().XRayInstructionThreshold));

3
lib/CodeGen/CodeGenModule.cpp
View File

@ -1967,9 +1967,6 @@ bool CodeGenModule::isInSanitizerBlacklist(llvm::GlobalVariable *GV,
bool CodeGenModule::imbueXRayAttrs(llvm::Function *Fn, SourceLocation Loc,
StringRef Category) const {
if (!LangOpts.XRayInstrument)
return false;
const auto &XRayFilter = getContext().getXRayFilter();
using ImbueAttr = XRayFunctionFilter::ImbueAttribute;
auto Attr = ImbueAttr::NONE;

29
test/CodeGen/xray-attributes-noxray-supported.cpp Normal file
View File

@ -0,0 +1,29 @@
// We want to ensure that the "never instrument" attributes show up even if we
// explicitly turn off XRay instrumentation.
//
// RUN: %clang_cc1 %s -fno-xray-instrument -std=c++11 -x c++ -emit-llvm -o - \
// RUN: -triple x86_64-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fno-xray-instrument -std=c++11 -x c++ -emit-llvm -o - \
// RUN: -triple arm-unknown-linux-gnu -target-abi apcs-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fno-xray-instrument -std=c++11 -x c++ -emit-llvm -o - \
// RUN: -triple mips-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fno-xray-instrument -std=c++11 -x c++ -emit-llvm -o - \
// RUN: -triple mipsel-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fno-xray-instrument -std=c++11 -x c++ -emit-llvm -o - \
// RUN: -triple mips64-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fno-xray-instrument -std=c++11 -x c++ -emit-llvm -o - \
// RUN: -triple mips64el-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fno-xray-instrument -std=c++11 -x c++ -emit-llvm -o - \
// RUN: -triple powerpc64le-unknown-linux-gnu | FileCheck %s
[[clang::xray_always_instrument]] void foo() {
// CHECK: define void @_Z3foov() #0
}
[[clang::xray_never_instrument]] void bar() {
// CHECK: define void @_Z3barv() #1
}
// CHECK-NOT: #0 = {{.*}}"function-instrument"="xray-always"
// CHECK: #1 = {{.*}}"function-instrument"="xray-never"

21
test/CodeGen/xray-attributes-supported.cpp
View File

@ -1,10 +1,17 @@
// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - -triple x86_64-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - -triple arm-unknown-linux-gnu -target-abi apcs-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - -triple mips-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - -triple mipsel-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - -triple mips64-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - -triple mips64el-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - -triple powerpc64le-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - \
// RUN: -triple x86_64-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - \
// RUN: -triple arm-unknown-linux-gnu -target-abi apcs-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - \
// RUN: -triple mips-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - \
// RUN: -triple mipsel-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - \
// RUN: -triple mips64-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - \
// RUN: -triple mips64el-unknown-linux-gnu | FileCheck %s
// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - \
// RUN: -triple powerpc64le-unknown-linux-gnu | FileCheck %s
// Make sure that the LLVM attribute for XRay-annotated functions do show up.
[[clang::xray_always_instrument]] void foo() {