[llvm] [llvm-exegesis] Remove unused Counter::read method (PR #76651)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/76651

This method was simply a wrapper around readOrError. All users within the llvm-exegesis code base should have been processing an actual error rather than using the wrapper. This patch removes the wrapper and rewrites the users (just 1) to use the readOrError method.

>From 0196a8780f2d3a378f0fd3b86a6e6b6590ca02de Mon Sep 17 00:00:00 2001
From: Aiden Grossman <agrossman154 at yahoo.com>
Date: Sat, 30 Dec 2023 15:37:56 -0800
Subject: [PATCH] [llvm-exegesis] Remove unused Counter::read method

This method was simply a wrapper around readOrError. All users within
the llvm-exegesis code base should have been processing an actual error
rather than using the wrapper. This patch removes the wrapper and
rewrites the users (just 1) to use the readOrError method.
---
 llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp |  6 +++++-
 llvm/tools/llvm-exegesis/lib/PerfHelper.cpp      | 13 -------------
 llvm/tools/llvm-exegesis/lib/PerfHelper.h        |  3 ---
 3 files changed, 5 insertions(+), 17 deletions(-)

diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
index 1ee59a86ebbdcf..c57fce970b2139 100644
--- a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
+++ b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
@@ -356,7 +356,11 @@ class SubProcessFunctionExecutorImpl
       if (ChildExitCode == 0) {
         // The child exited succesfully, read counter values and return
         // success
-        CounterValues[0] = Counter->read();
+        auto CounterValueOrErr = Counter->readOrError();
+        if (!CounterValueOrErr)
+          return CounterValueOrErr.takeError();
+        CounterValues.swap(*CounterValueOrErr);
+
         return Error::success();
       }
       // The child exited, but not successfully
diff --git a/llvm/tools/llvm-exegesis/lib/PerfHelper.cpp b/llvm/tools/llvm-exegesis/lib/PerfHelper.cpp
index 3ff1745e9e0629..314de1ec32366f 100644
--- a/llvm/tools/llvm-exegesis/lib/PerfHelper.cpp
+++ b/llvm/tools/llvm-exegesis/lib/PerfHelper.cpp
@@ -148,17 +148,6 @@ void Counter::stop() {
     ioctl(FileDescriptor, PERF_EVENT_IOC_DISABLE, 0);
 }
 
-int64_t Counter::read() const {
-  auto ValueOrError = readOrError();
-  if (ValueOrError) {
-    if (!ValueOrError.get().empty())
-      return ValueOrError.get()[0];
-    errs() << "Counter has no reading\n";
-  } else
-    errs() << ValueOrError.takeError() << "\n";
-  return -1;
-}
-
 llvm::Expected<llvm::SmallVector<int64_t, 4>>
 Counter::readOrError(StringRef /*unused*/) const {
   int64_t Count = 0;
@@ -187,8 +176,6 @@ void Counter::start() {}
 
 void Counter::stop() {}
 
-int64_t Counter::read() const { return 42; }
-
 llvm::Expected<llvm::SmallVector<int64_t, 4>>
 Counter::readOrError(StringRef /*unused*/) const {
   if (IsDummyEvent) {
diff --git a/llvm/tools/llvm-exegesis/lib/PerfHelper.h b/llvm/tools/llvm-exegesis/lib/PerfHelper.h
index a50974f0a67be9..894aac1f197ed1 100644
--- a/llvm/tools/llvm-exegesis/lib/PerfHelper.h
+++ b/llvm/tools/llvm-exegesis/lib/PerfHelper.h
@@ -95,9 +95,6 @@ class Counter {
   /// Stops the measurement of the event.
   void stop();
 
-  /// Returns the current value of the counter or -1 if it cannot be read.
-  int64_t read() const;
-
   /// Returns the current value of the counter or error if it cannot be read.
   /// FunctionBytes: The benchmark function being executed.
   /// This is used to filter out the measurements to ensure they are only