[pgo] Improve check for enablesValueProfiling

[paulkirth]

Summary

Currently, the check for enablesValueProfiling only considers if it was
specifically added, or is enabled by default under IR profiling. However, we
allow value profiling to be disabled through the DisableValueProfiling flag,
but do not account for this path in InstrProfiling. This change exposes that
flag from PGOInstrumentation.cpp, and uses it as part of its check for whether
value profiling is enabled.

llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp

 
 #define DEBUG_TYPE "instrprof"
 
 namespace llvm {
 cl::opt<bool>
     DebugInfoCorrelate("debug-info-correlate",
                        cl::desc("Use debug info to correlate profiles."),
                        cl::init(false));
+extern cl::opt<bool> DisableValueProfiling;
 } // namespace llvm
 
 namespace {
 
 cl::opt<bool> DoHashBasedCounterSplit(
     "hash-based-counter-split",
     cl::desc("Rename counter variable of a comdat function based on cfg hash"),
     cl::init(true));
if (!MD)
     return 0;
 
   // If the flag is a ConstantAsMetadata, it should be an integer representable
   // in 64-bits.
   return cast<ConstantInt>(MD->getValue())->getZExtValue();
 }
 
 static bool enablesValueProfiling(const Module &M) {
-  return isIRPGOFlagSet(&M) ||
-         getIntModuleFlagOrZero(M, "EnableValueProfiling") != 0;
+  return (isIRPGOFlagSet(&M) ||
+          getIntModuleFlagOrZero(M, "EnableValueProfiling") != 0) &&
+         !DisableValueProfiling;
 }
 
 // Conservatively returns true if data variables may be referenced by code.
 static bool profDataReferencedByCode(const Module &M) {
   return enablesValueProfiling(M);
 }
 
 static inline bool shouldRecordFunctionAddr(Function *F) {

llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp

PGOTestProfileFile("pgo-test-profile-file", cl::init(""), cl::Hidden,
                        cl::desc("Specify the path of profile data file. This is"
                                 "mainly for test purpose."));
 static cl::opt<std::string> PGOTestProfileRemappingFile(
     "pgo-test-profile-remapping-file", cl::init(""), cl::Hidden,
     cl::value_desc("filename"),
     cl::desc("Specify the path of profile remapping file. This is mainly for "
              "test purpose."));
 
-// Command line option to disable value profiling. The default is false:
-// i.e. value profiling is enabled by default. This is for debug purpose.
-static cl::opt<bool> DisableValueProfiling("disable-vp", cl::init(false),
-                                           cl::Hidden,
-                                           cl::desc("Disable Value Profiling"));
-
 // Command line option to set the maximum number of VP annotations to write to
 // the metadata for a single indirect call callsite.
 static cl::opt<unsigned> MaxNumAnnotations(
     "icp-max-annotations", cl::init(3), cl::Hidden,
     cl::desc("Max number of annotations for a single indirect "
              "call callsite"));
 
 // Command line option to set the maximum number of value annotations

 
 namespace llvm {
 // Command line option to enable/disable the warning about a hash mismatch in
 // the profile data.
 cl::opt<bool>
     NoPGOWarnMismatch("no-pgo-warn-mismatch", cl::init(false), cl::Hidden,
                       cl::desc("Use this option to turn off/on "
                                "warnings about profile cfg mismatch."));
+// Command line option to disable value profiling. The default is false:
+// i.e. value profiling is enabled by default. This is for debug purpose.
+cl::opt<bool> DisableValueProfiling("disable-vp", cl::init(false), cl::Hidden,
+                                    cl::desc("Disable Value Profiling"));
+
 } // namespace llvm
 
 // Command line option to enable/disable the warning about a hash mismatch in
 // the profile data for Comdat functions, which often turns out to be false
 // positive due to the pre-instrumentation inline.
 static cl::opt<bool> NoPGOWarnMismatchComdatWeak(
     "no-pgo-warn-mismatch-comdat-weak", cl::init(true), cl::Hidden,
     cl::desc("The option is used to turn on/off "

llvm/test/Instrumentation/InstrProfiling/comdat.ll

 ; There are two main cases where comdats are necessary:
 ; 1. standard inline functions (weak_odr / linkonce_odr)
 ; 2. available externally functions (C99 inline / extern template / dllimport)
 ; Check that we do the right thing for the two object formats with comdats, ELF
 ; and COFF.
 ;
 ; Test comdat functions. Non-comdat functions are tested in linkage.ll.
 ; RUN: split-file %s %t
 ; RUN: cat %t/main.ll %t/disable.ll > %t0.ll
 ; RUN: cat %t/main.ll %t/enable.ll > %t1.ll
 ; RUN: opt < %t0.ll -mtriple=x86_64-linux -passes=instrprof -S | FileCheck %s --check-prefixes=ELF,ELF0
 ; RUN: opt < %t1.ll -mtriple=x86_64-linux -passes=instrprof -S | FileCheck %s --check-prefixes=ELF,ELF1
+; RUN: opt < %t1.ll -mtriple=x86_64-linux -passes=instrprof -disable-vp -S | FileCheck %s --check-prefixes=ELF,ELF0
 ; RUN: opt < %t0.ll -mtriple=x86_64-windows -passes=instrprof -S | FileCheck %s --check-prefixes=COFF,COFF0
 ; RUN: opt < %t1.ll -mtriple=x86_64-windows -passes=instrprof -S | FileCheck %s --check-prefixes=COFF,COFF1
 
 ;--- main.ll
 declare void @llvm.instrprof.increment(ptr, i64, i32, i32)
 
 $foo_inline = comdat any
 $foo_extern = comdat any