[llvm-exegesis] Add tablegen support for validation counters

[boomanaiden154]

This patch adds support in the llvm-exegesis tablegen emitter for validation counters. Full support for validation counters in llvm-exegesis is added in a future patch.

[llvmbot]

@llvm/pr-subscribers-tools-llvm-exegesis

@llvm/pr-subscribers-backend-x86

Author: Aiden Grossman (boomanaiden154)

Changes

This patch adds support in the llvm-exegesis tablegen emitter for validation counters. Full support for validation counters in llvm-exegesis is added in a future patch.

---

Full diff: https://github.com/llvm/llvm-project/pull/76652.diff

5 Files Affected:

• (modified) llvm/include/llvm/Target/TargetPfmCounters.td (+19)
• (modified) llvm/lib/Target/X86/X86PfmCounters.td (+6)
• (modified) llvm/tools/llvm-exegesis/lib/Target.cpp (+7-6)
• (modified) llvm/tools/llvm-exegesis/lib/Target.h (+11)
• (modified) llvm/utils/TableGen/ExegesisEmitter.cpp (+26-2)

diff --git a/llvm/include/llvm/Target/TargetPfmCounters.td b/llvm/include/llvm/Target/TargetPfmCounters.td
index b00f3e19c35f90..72f6b39f4878f4 100644
--- a/llvm/include/llvm/Target/TargetPfmCounters.td
+++ b/llvm/include/llvm/Target/TargetPfmCounters.td
@@ -28,6 +28,22 @@ class PfmIssueCounter<string resource_name, string counter>
   string ResourceName = resource_name;
 }
 
+class ValidationEvent <int event_number> {
+  int EventNumber = event_number;
+}
+
+def L1DCacheLoadMiss    : ValidationEvent<0>;
+def InstructionRetired  : ValidationEvent<1>;
+def DataTLBLoadMiss     : ValidationEvent<2>;
+def DataTLBStoreMiss    : ValidationEvent<3>;
+
+// Validation counters can be tied to a specific event
+class PfmValidationCounter<ValidationEvent event_type, string counter>
+    : PfmCounter<counter> {
+  // The name of the event that the validation counter detects.
+  ValidationEvent EventType = event_type;
+}
+
 def NoPfmCounter : PfmCounter <""> {}
 
 // Set of PfmCounters for measuring sched model characteristics.
@@ -38,6 +54,9 @@ class ProcPfmCounters {
   PfmCounter UopsCounter = NoPfmCounter;
   // Processors can define how to measure issued uops by defining IssueCounters.
   list<PfmIssueCounter> IssueCounters = [];
+  // Processor can list mappings between validation events and real counters
+  // to measure the specified events.
+  list<PfmValidationCounter> ValidationCounters = [];
 }
 
 // A binding of a set of counters to a CPU.
diff --git a/llvm/lib/Target/X86/X86PfmCounters.td b/llvm/lib/Target/X86/X86PfmCounters.td
index 49ef6efc6aecf2..99cac504f157d3 100644
--- a/llvm/lib/Target/X86/X86PfmCounters.td
+++ b/llvm/lib/Target/X86/X86PfmCounters.td
@@ -275,6 +275,9 @@ def ZnVer2PfmCounters : ProcPfmCounters {
     PfmIssueCounter<"Zn2AGU", "ls_dispatch:ld_st_dispatch + ls_dispatch:ld_dispatch + ls_dispatch:store_dispatch">,
     PfmIssueCounter<"Zn2Divider", "div_op_count">
   ];
+  let ValidationCounters = [
+    PfmValidationCounter<InstructionRetired, "RETIRED_INSTRUCTIONS">
+  ];
 }
 def : PfmCountersBinding<"znver2", ZnVer2PfmCounters>;
 
@@ -288,6 +291,9 @@ def ZnVer3PfmCounters : ProcPfmCounters {
     PfmIssueCounter<"Zn3Store", "ls_dispatch:store_dispatch">,
     PfmIssueCounter<"Zn3Divider", "div_op_count">
   ];
+  let ValidationCounters = [
+    PfmValidationCounter<InstructionRetired, "RETIRED_INSTRUCTIONS">
+  ];
 }
 def : PfmCountersBinding<"znver3", ZnVer3PfmCounters>;
 
diff --git a/llvm/tools/llvm-exegesis/lib/Target.cpp b/llvm/tools/llvm-exegesis/lib/Target.cpp
index 23c80e5b98953a..20b4afb9b8f676 100644
--- a/llvm/tools/llvm-exegesis/lib/Target.cpp
+++ b/llvm/tools/llvm-exegesis/lib/Target.cpp
@@ -147,13 +147,14 @@ std::unique_ptr<BenchmarkRunner> ExegesisTarget::createUopsBenchmarkRunner(
                                                ExecutionMode);
 }
 
-static_assert(std::is_trivial_v<PfmCountersInfo>,
-              "We shouldn't have dynamic initialization here");
-const PfmCountersInfo PfmCountersInfo::Default = {nullptr, nullptr, nullptr,
-                                                  0u};
+const PfmCountersInfo PfmCountersInfo::Default = {
+    nullptr, nullptr, nullptr, 0u, {}};
 const PfmCountersInfo PfmCountersInfo::Dummy = {
-    pfm::PerfEvent::DummyEventString, pfm::PerfEvent::DummyEventString, nullptr,
-    0u};
+    pfm::PerfEvent::DummyEventString,
+    pfm::PerfEvent::DummyEventString,
+    nullptr,
+    0u,
+    {}};
 
 const PfmCountersInfo &ExegesisTarget::getPfmCounters(StringRef CpuName) const {
   assert(llvm::is_sorted(
diff --git a/llvm/tools/llvm-exegesis/lib/Target.h b/llvm/tools/llvm-exegesis/lib/Target.h
index c37dd8b7082162..3956bc983181f6 100644
--- a/llvm/tools/llvm-exegesis/lib/Target.h
+++ b/llvm/tools/llvm-exegesis/lib/Target.h
@@ -32,6 +32,8 @@
 #include "llvm/TargetParser/SubtargetFeature.h"
 #include "llvm/TargetParser/Triple.h"
 
+#include <unordered_map>
+
 namespace llvm {
 namespace exegesis {
 
@@ -39,6 +41,13 @@ extern cl::OptionCategory Options;
 extern cl::OptionCategory BenchmarkOptions;
 extern cl::OptionCategory AnalysisOptions;
 
+enum ValidationEvent {
+  L1DCacheLoadMiss,
+  InstructionRetired,
+  DataTLBLoadMiss,
+  DataTLBStoreMiss
+};
+
 struct PfmCountersInfo {
   // An optional name of a performance counter that can be used to measure
   // cycles.
@@ -59,6 +68,8 @@ struct PfmCountersInfo {
   const IssueCounter *IssueCounters;
   unsigned NumIssueCounters;
 
+  std::unordered_map<ValidationEvent, const char *> ValidationCounters;
+
   static const PfmCountersInfo Default;
   static const PfmCountersInfo Dummy;
 };
diff --git a/llvm/utils/TableGen/ExegesisEmitter.cpp b/llvm/utils/TableGen/ExegesisEmitter.cpp
index 736f1220be14dd..247ed83f25ea64 100644
--- a/llvm/utils/TableGen/ExegesisEmitter.cpp
+++ b/llvm/utils/TableGen/ExegesisEmitter.cpp
@@ -22,6 +22,8 @@
 #include <string>
 #include <vector>
 
+#include <iostream>
+
 using namespace llvm;
 
 #define DEBUG_TYPE "exegesis-emitter"
@@ -81,6 +83,11 @@ collectPfmCounters(const RecordKeeper &Records) {
                         "duplicate ResourceName " + ResourceName);
       AddPfmCounterName(IssueCounter);
     }
+
+    for (const Record *ValidationCounter :
+         Def->getValueAsListOfDefs("ValidationCounters"))
+      AddPfmCounterName(ValidationCounter);
+
     AddPfmCounterName(Def->getValueAsDef("CycleCounter"));
     AddPfmCounterName(Def->getValueAsDef("UopsCounter"));
   }
@@ -109,6 +116,8 @@ void ExegesisEmitter::emitPfmCountersInfo(const Record &Def,
       Def.getValueAsDef("UopsCounter")->getValueAsString("Counter");
   const size_t NumIssueCounters =
       Def.getValueAsListOfDefs("IssueCounters").size();
+  const size_t NumValidationCounters =
+      Def.getValueAsListOfDefs("ValidationCounters").size();
 
   OS << "\nstatic const PfmCountersInfo " << Target << Def.getName()
      << " = {\n";
@@ -129,10 +138,25 @@ void ExegesisEmitter::emitPfmCountersInfo(const Record &Def,
 
   // Issue Counters
   if (NumIssueCounters == 0)
-    OS << "  nullptr,  // No issue counters.\n  0\n";
+    OS << "  nullptr, 0, // No issue counters\n";
   else
     OS << "  " << Target << "PfmIssueCounters + " << IssueCountersTableOffset
-       << ", " << NumIssueCounters << " // Issue counters.\n";
+       << ", " << NumIssueCounters << ", // Issue counters.\n";
+
+  // Validation Counters
+  if (NumValidationCounters == 0)
+    OS << "  {} // No validation counters.\n";
+  else {
+    OS << "  {\n";
+    for (const Record *ValidationCounter :
+         Def.getValueAsListOfDefs("ValidationCounters")) {
+      OS << "    { " << ValidationCounter->getValueAsDef("EventType")->getName()
+         << ", " << Target << "PfmCounterNames["
+         << getPfmCounterId(ValidationCounter->getValueAsString("Counter"))
+         << "]}\n";
+    }
+    OS << "  } // Validation counters.\n";
+  }
 
   OS << "};\n";
   IssueCountersTableOffset += NumIssueCounters;

[boomanaiden154]

@legrosbuffle When you get a chance, are you able to take another look at this along with the other patches in the stack?

1. [llvm-exegesis] Add support for validation counters #76653
2. [llvm-exegesis] Add additional validation counters #76788

I also have a couple other patches that would be nice to land soon. It would be great if you could take a look at them also:

1. [llvm-exegesis] Fix snippet value scaling #77226
2. [llvm-exegesis] Make duplicate snippet repetitor produce whole snippets #77224
3. [llvm-exegesis] Add middle half repetition mode #77020
4. [llvm-exegesis] Add support for warmup iterations #76895