Skip to content

Commit

Permalink
Add -finstrument-function-entry-bare flag
Browse files Browse the repository at this point in the history
This is an instrumentation flag that's similar to
-finstrument-functions, but it only inserts calls on function entry, the
calls are inserted post-inlining, and they don't take any arugments.

This is intended for users who want to instrument function entry with
minimal overhead.

(-pg would be another alternative, but forces frame pointer emission and
affects link flags, so is probably best left alone to be used for
generating gcov data.)

Differential revision: https://reviews.llvm.org/D40276

llvm-svn: 318785
  • Loading branch information
zmodem committed Nov 21, 2017
1 parent d97c0f7 commit 14e8a5a
Showing 6 changed files with 39 additions and 11 deletions.
2 changes: 2 additions & 0 deletions clang/include/clang/Driver/Options.td
Original file line number Diff line number Diff line change
@@ -1030,6 +1030,8 @@ def finstrument_functions : Flag<["-"], "finstrument-functions">, Group<f_Group>
HelpText<"Generate calls to instrument function entry and exit">;
def finstrument_functions_after_inlining : Flag<["-"], "finstrument-functions-after-inlining">, Group<f_Group>, Flags<[CC1Option]>,
HelpText<"Like -finstrument-functions, but insert the calls after inlining">;
def finstrument_function_entry_bare : Flag<["-"], "finstrument-function-entry-bare">, Group<f_Group>, Flags<[CC1Option]>,
HelpText<"Instrument function entry only, after inlining, without arguments to the instrumentation call">;

def fxray_instrument : Flag<["-"], "fxray-instrument">, Group<f_Group>,
Flags<[CC1Option]>,
2 changes: 2 additions & 0 deletions clang/include/clang/Frontend/CodeGenOptions.def
Original file line number Diff line number Diff line change
@@ -78,6 +78,8 @@ CODEGENOPT(InstrumentFunctions , 1, 0) ///< Set when -finstrument-functions is
///< enabled.
CODEGENOPT(InstrumentFunctionsAfterInlining , 1, 0) ///< Set when
///< -finstrument-functions-after-inlining is enabled.
CODEGENOPT(InstrumentFunctionEntryBare , 1, 0) ///< Set when
///< -finstrument-function-entry-bare is enabled.

CODEGENOPT(XRayInstrumentFunctions , 1, 0) ///< Set when -fxray-instrument is
///< enabled.
24 changes: 15 additions & 9 deletions clang/lib/CodeGen/CodeGenFunction.cpp
Original file line number Diff line number Diff line change
@@ -355,10 +355,11 @@ void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
llvm::DebugLoc Loc = EmitReturnBlock();

if (ShouldInstrumentFunction()) {
CurFn->addFnAttr(!CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining
? "instrument-function-exit"
: "instrument-function-exit-inlined",
"__cyg_profile_func_exit");
if (CGM.getCodeGenOpts().InstrumentFunctions)
CurFn->addFnAttr("instrument-function-exit", "__cyg_profile_func_exit");
if (CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining)
CurFn->addFnAttr("instrument-function-exit-inlined",
"__cyg_profile_func_exit");
}

// Emit debug descriptor for function end.
@@ -443,7 +444,8 @@ void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
/// instrumented with __cyg_profile_func_* calls
bool CodeGenFunction::ShouldInstrumentFunction() {
if (!CGM.getCodeGenOpts().InstrumentFunctions &&
!CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining)
!CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining &&
!CGM.getCodeGenOpts().InstrumentFunctionEntryBare)
return false;
if (!CurFuncDecl || CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>())
return false;
@@ -982,10 +984,14 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
}

if (ShouldInstrumentFunction()) {
Fn->addFnAttr(!CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining
? "instrument-function-entry"
: "instrument-function-entry-inlined",
"__cyg_profile_func_enter");
if (CGM.getCodeGenOpts().InstrumentFunctions)
CurFn->addFnAttr("instrument-function-entry", "__cyg_profile_func_enter");
if (CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining)
CurFn->addFnAttr("instrument-function-entry-inlined",
"__cyg_profile_func_enter");
if (CGM.getCodeGenOpts().InstrumentFunctionEntryBare)
CurFn->addFnAttr("instrument-function-entry-inlined",
"__cyg_profile_func_enter_bare");
}

// Since emitting the mcount call here impacts optimizations such as function
7 changes: 5 additions & 2 deletions clang/lib/Driver/ToolChains/Clang.cpp
Original file line number Diff line number Diff line change
@@ -3554,8 +3554,11 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
options::OPT_fno_unique_section_names, true))
CmdArgs.push_back("-fno-unique-section-names");

Args.AddLastArg(CmdArgs, options::OPT_finstrument_functions,
options::OPT_finstrument_functions_after_inlining);
if (auto *A = Args.getLastArg(
options::OPT_finstrument_functions,
options::OPT_finstrument_functions_after_inlining,
options::OPT_finstrument_function_entry_bare))
A->render(Args, CmdArgs);

addPGOAndCoverageFlags(C, D, Output, Args, CmdArgs);

2 changes: 2 additions & 0 deletions clang/lib/Frontend/CompilerInvocation.cpp
Original file line number Diff line number Diff line change
@@ -782,6 +782,8 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
Opts.InstrumentFunctions = Args.hasArg(OPT_finstrument_functions);
Opts.InstrumentFunctionsAfterInlining =
Args.hasArg(OPT_finstrument_functions_after_inlining);
Opts.InstrumentFunctionEntryBare =
Args.hasArg(OPT_finstrument_function_entry_bare);
Opts.XRayInstrumentFunctions = Args.hasArg(OPT_fxray_instrument);
Opts.XRayInstructionThreshold =
getLastArgIntValue(Args, OPT_fxray_instruction_threshold_EQ, 200, Diags);
13 changes: 13 additions & 0 deletions clang/test/CodeGen/instrument-functions.c
Original file line number Diff line number Diff line change
@@ -1,21 +1,34 @@
// RUN: %clang_cc1 -S -debug-info-kind=standalone -emit-llvm -o - %s -finstrument-functions -disable-llvm-passes | FileCheck %s
// RUN: %clang_cc1 -S -debug-info-kind=standalone -emit-llvm -o - %s -finstrument-function-entry-bare -disable-llvm-passes | FileCheck -check-prefix=BARE %s

int test1(int x) {
// CHECK: @test1(i32 {{.*}}%x) #[[ATTR1:[0-9]+]]
// CHECK: ret

// BARE: @test1(i32 {{.*}}%x) #[[ATTR1:[0-9]+]]
// BARE: ret
return x;
}

int test2(int) __attribute__((no_instrument_function));
int test2(int x) {
// CHECK: @test2(i32 {{.*}}%x) #[[ATTR2:[0-9]+]]
// CHECK: ret

// BARE: @test2(i32 {{.*}}%x) #[[ATTR2:[0-9]+]]
// BARE: ret
return x;
}

// CHECK: attributes #[[ATTR1]] =
// CHECK-SAME: "instrument-function-entry"="__cyg_profile_func_enter"
// CHECK-SAME: "instrument-function-exit"="__cyg_profile_func_exit"

// BARE: attributes #[[ATTR1]] =
// BARE-SAME: "instrument-function-entry-inlined"="__cyg_profile_func_enter_bare"

// CHECK: attributes #[[ATTR2]] =
// CHECK-NOT: "instrument-function-entry"

// BARE: attributes #[[ATTR2]] =
// BARE-NOT: "instrument-function-entry"

0 comments on commit 14e8a5a

Please sign in to comment.