[BOLT][NFC] Replace stdio with raw_ostream in CallGraph

[nhuhuan]

Summary

Replacing stdio functions, e.g., fopen, fprintf, with raw_ostream.

Test Plan:

ninja check-bolt

[Amir]

Looking good. Let's address some issues:

1. Please retitle the diff as "[BOLT][NFC] Replace stdio with raw_ostream in CallGraph". The commit title should be a declarative statement, and explicit about where the change is made.
2. While we're on it, let's add an option to use printDot method. Please use an example of PrintCFG option.
3. Inline comments.

bolt/include/bolt/Passes/CallGraph.h

17

Are all of the new includes here really needed? Can you please prune the added includes as much as possible?

165

171

Please keep the type as is - there has been an effort to reduce the number of auto's in the codebase. LLVM coding style advises to be explicit about type in most cases: https://llvm.org/docs/CodingStandards.html#use-auto-type-deduction-to-make-code-more-readable

182–185

You can preserve the requested precision using the format method described here: https://llvm.org/doxygen/Format_8h_source.html (see comment on the top).

[nhuhuan]

bolt/include/bolt/Passes/CallGraph.h

17

I included cmath and iomanip to use std::fixed and std::setprecision to get right format for floating-point value.
But they are not compatible with raw_ostream, so I removed them, and forgot to remove cmath.
Including <string> is not necessary as it was already included in llvm/Support/FileSystem.h.
I will remove all of them in the next commit.

[nhuhuan]

Prune unnecessary include, restrict use of auto keyword, format floating-point values.

[Amir]

Please address the review comments and mark them as resolved.

bolt/include/bolt/Passes/CallGraph.h

171

Let's keep iteration as is here and below

173–175

Let's drop the explicit type cast here and below.
I don't think it's needed given that

• NodeId is an alias to size_t,
• Nodes[].samples() returns uint64_t,
• Nodes[].size() returns size_t.

177

Let's remove the added newline to make it easier to compare code side-by-side.

189

No need to explicitly close OS as the object is local to the scope and the fd is closed by destructor.

[nhuhuan]

Address new comments

[Amir]

bolt/include/bolt/Passes/CallGraph.h

182–185

There are still some type casts left on this line

[nhuhuan]

Remove remaining redundant type casts

bolt/include/bolt/Passes/CallGraph.h

 //===- bolt/Passes/CallGraph.h ----------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef BOLT_PASSES_CALLGRAPH_H
 #define BOLT_PASSES_CALLGRAPH_H
 
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/raw_ostream.h"
 #include <cassert>
 #include <cstdint>
-#include <cstdio>
 #include <unordered_set>
 #include <vector>
 
 namespace llvm {
 namespace bolt {
 
 // TODO: find better place for this
 inline int64_t hashCombine(const int64_t Seed, const int64_t Val) {
   std::hash<int64_t> Hasher;
   return Seed ^ (Hasher(Val) + 0x9e3779b9 + (Seed << 6) + (Seed >> 2));
void setSamples(const NodeId Id, uint64_t Samples) {
     Nodes[Id].Samples = Samples;
   }
 
   std::vector<Node> Nodes;
   ArcsType Arcs;
 };
 
 template <class L> void CallGraph::printDot(char *FileName, L GetLabel) const {
-  FILE *File = fopen(FileName, "wt");
-  if (!File)
+  std::error_code EC;
+  raw_fd_ostream OS(std::string(FileName), EC, sys::fs::OF_None);
+  if (EC)
     return;
 
-  fprintf(File, "digraph g {\n");
+  OS << "digraph g {\n";
   for (NodeId F = 0; F < Nodes.size(); F++) {
     if (Nodes[F].samples() == 0)
       continue;
-    fprintf(File, "f%lu [label=\"%s\\nsamples=%u\\nsize=%u\"];\n", F,
-            GetLabel(F), Nodes[F].samples(), Nodes[F].size());
+    OS << "f" << F << " [label=\"" << GetLabel(F)
+       << "\\nsamples=" << Nodes[F].samples() << "\\nsize=" << Nodes[F].size()
+       << "\"];\n";
   }
   for (NodeId F = 0; F < Nodes.size(); F++) {
     if (Nodes[F].samples() == 0)
       continue;
     for (NodeId Dst : Nodes[F].successors()) {
       ArcConstIterator Arc = findArc(F, Dst);
-      fprintf(
-          File,
-          "f%lu -> f%u [label=\"normWgt=%.3lf,weight=%.0lf,callOffset=%.1lf\"];"
-          "\n",
-          F, Dst, Arc->normalizedWeight(), Arc->weight(), Arc->avgCallOffset());
+      OS << "f" << F << " -> f" << Dst
+         << " [label=\"normWgt=" << format("%.3lf", Arc->normalizedWeight())
+         << ",weight=" << format("%.0lf", Arc->weight())
+         << ",callOffset=" << format("%.1lf", Arc->avgCallOffset()) << "\"];\n";
     }
   }
-  fprintf(File, "}\n");
-  fclose(File);
+  OS << "}\n";
 }
 
 } // namespace bolt
 } // namespace llvm
 
 #endif