r342200 - [XRay][clang] Emit "never-instrument" attribute

Dean Michael Berris via cfe-commits cfe-commits at lists.llvm.org
Thu Sep 13 18:59:12 PDT 2018


Author: dberris
Date: Thu Sep 13 18:59:12 2018
New Revision: 342200

URL: http://llvm.org/viewvc/llvm-project?rev=342200&view=rev
Log:
[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

Added:
    cfe/trunk/test/CodeGen/xray-attributes-noxray-supported.cpp
Modified:
    cfe/trunk/lib/CodeGen/CodeGenFunction.cpp
    cfe/trunk/lib/CodeGen/CodeGenModule.cpp
    cfe/trunk/test/CodeGen/xray-attributes-supported.cpp

Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.cpp?rev=342200&r1=342199&r2=342200&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenFunction.cpp (original)
+++ cfe/trunk/lib/CodeGen/CodeGenFunction.cpp Thu Sep 13 18:59:12 2018
@@ -901,21 +901,21 @@ void CodeGenFunction::StartFunction(Glob
   }
 
   // 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));

Modified: cfe/trunk/lib/CodeGen/CodeGenModule.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenModule.cpp?rev=342200&r1=342199&r2=342200&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenModule.cpp (original)
+++ cfe/trunk/lib/CodeGen/CodeGenModule.cpp Thu Sep 13 18:59:12 2018
@@ -1967,9 +1967,6 @@ bool CodeGenModule::isInSanitizerBlackli
 
 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;

Added: cfe/trunk/test/CodeGen/xray-attributes-noxray-supported.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/xray-attributes-noxray-supported.cpp?rev=342200&view=auto
==============================================================================
--- cfe/trunk/test/CodeGen/xray-attributes-noxray-supported.cpp (added)
+++ cfe/trunk/test/CodeGen/xray-attributes-noxray-supported.cpp Thu Sep 13 18:59:12 2018
@@ -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"
+

Modified: cfe/trunk/test/CodeGen/xray-attributes-supported.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/xray-attributes-supported.cpp?rev=342200&r1=342199&r2=342200&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/xray-attributes-supported.cpp (original)
+++ cfe/trunk/test/CodeGen/xray-attributes-supported.cpp Thu Sep 13 18:59:12 2018
@@ -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() {




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