[PATCH] D156006: [InstrProf] Emit warnings when correlating lightweight profiles

[Ellis Hoag via Phabricator via llvm-commits]

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Emit warnings when `InstrProfCorrelator` finds problems with debug info for lightweight instrumentation profile correlation. To prevent excessive printing, only emit the first 5 warnings.

In addition, remove a diagnostic about missing debug info in `InstrProfiling.cpp`. Some compiler-generated functions, e.g., `__clang_call_terminate`, does not emit debug info and will fail a build if `-Werror` is used. This warning is not actionable by the user and I have not seen non-compiler-generated functions fail this test.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D156006

Files:
  llvm/lib/ProfileData/InstrProfCorrelator.cpp
  llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp


Index: llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -1056,12 +1056,6 @@
           Annotations);
       CounterPtr->addDebugInfo(DICounter);
       DB.finalize();
-    } else {
-      std::string Msg = ("Missing debug info for function " + Fn->getName() +
-                         "; required for profile correlation.")
-                            .str();
-      Ctx.diagnose(
-          DiagnosticInfoPGOProfile(M->getName().data(), Msg, DS_Warning));
     }
   }
 
Index: llvm/lib/ProfileData/InstrProfCorrelator.cpp
===================================================================
--- llvm/lib/ProfileData/InstrProfCorrelator.cpp
+++ llvm/lib/ProfileData/InstrProfCorrelator.cpp
@@ -16,6 +16,8 @@
 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
 #include "llvm/Object/MachO.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Support/WithColor.h"
 #include <optional>
 
 #define DEBUG_TYPE "correlator"
@@ -261,6 +263,8 @@
 template <class IntPtrT>
 void DwarfInstrProfCorrelator<IntPtrT>::correlateProfileDataImpl(
     InstrProfCorrelator::CorrelationData *Data) {
+  // The negation of the maximum number of warnings we would like to emit
+  int NumSuppressedWarnings = -5;
   auto maybeAddProbe = [&](DWARFDie Die) {
     if (!isDIEOfProbe(Die))
       return;
@@ -297,28 +301,30 @@
       }
     }
     if (!FunctionName || !CFGHash || !CounterPtr || !NumCounters) {
-      LLVM_DEBUG(dbgs() << "Incomplete DIE for probe\n\tFunctionName: "
-                        << FunctionName << "\n\tCFGHash: " << CFGHash
-                        << "\n\tCounterPtr: " << CounterPtr
-                        << "\n\tNumCounters: " << NumCounters);
-      LLVM_DEBUG(Die.dump(dbgs()));
+      if (++NumSuppressedWarnings < 1) {
+        WithColor::warning()
+            << "Incomplete DIE for function " << FunctionName
+            << ": CFGHash=" << CFGHash << "  CounterPtr=" << CounterPtr
+            << "  NumCounters=" << NumCounters << "\n";
+        LLVM_DEBUG(Die.dump(dbgs()));
+      }
       return;
     }
     uint64_t CountersStart = this->Ctx->CountersSectionStart;
     uint64_t CountersEnd = this->Ctx->CountersSectionEnd;
     if (*CounterPtr < CountersStart || *CounterPtr >= CountersEnd) {
-      LLVM_DEBUG(
-          dbgs() << "CounterPtr out of range for probe\n\tFunction Name: "
-                 << FunctionName << "\n\tExpected: [0x"
-                 << Twine::utohexstr(CountersStart) << ", 0x"
-                 << Twine::utohexstr(CountersEnd) << ")\n\tActual: 0x"
-                 << Twine::utohexstr(*CounterPtr));
-      LLVM_DEBUG(Die.dump(dbgs()));
+      if (++NumSuppressedWarnings < 1) {
+        WithColor::warning()
+            << format("CounterPtr out of range for function %s: Actual=0x%x "
+                      "Expected=[0x%x, 0x%x)\n",
+                      *FunctionName, *CounterPtr, CountersStart, CountersEnd);
+        LLVM_DEBUG(Die.dump(dbgs()));
+      }
       return;
     }
-    if (!FunctionPtr) {
-      LLVM_DEBUG(dbgs() << "Could not find address of " << *FunctionName
-                        << "\n");
+    if (!FunctionPtr && ++NumSuppressedWarnings < 1) {
+      WithColor::warning() << format("Could not find address of function %s\n",
+                                     *FunctionName);
       LLVM_DEBUG(Die.dump(dbgs()));
     }
     IntPtrT CounterOffset = *CounterPtr - CountersStart;
@@ -348,4 +354,8 @@
   for (auto &CU : DICtx->dwo_units())
     for (const auto &Entry : CU->dies())
       maybeAddProbe(DWARFDie(CU.get(), &Entry));
+
+  if (NumSuppressedWarnings > 0)
+    WithColor::warning() << format("Suppressed %d additional warnings\n",
+                                   NumSuppressedWarnings);
 }


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