llvmbot wrote:

<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Serge Pavlov (spavloff)

<details>
<summary>Changes</summary>

There are checks in clang codebase that determine the type of source file, 
associated with a given location - specifically, if it is an ordonary file or 
comes from sources like command-line options or a built-in definitions. These 
checks often rely on calls to `getPresumedLoc`, which is relatively expensive.  
In certain cases, these checks are combined, leading to repeated calculations 
of the costly function negatively affecting compile time.

This change tries to optimize such checks. It must fix compile time regression 
introduced in https://github.com/llvm/llvm-project/pull/137306/.

---
Full diff: https://github.com/llvm/llvm-project/pull/139492.diff


4 Files Affected:

- (modified) clang/include/clang/Basic/SourceManager.h (+9) 
- (modified) clang/lib/ExtractAPI/ExtractAPIConsumer.cpp (+1-2) 
- (modified) clang/lib/Frontend/PrintPreprocessedOutput.cpp (+1-2) 
- (modified) clang/lib/Lex/PPDirectives.cpp (+3-5) 


``````````diff
diff --git a/clang/include/clang/Basic/SourceManager.h 
b/clang/include/clang/Basic/SourceManager.h
index e0f1ea435d54e..8859865a1ee7e 100644
--- a/clang/include/clang/Basic/SourceManager.h
+++ b/clang/include/clang/Basic/SourceManager.h
@@ -1529,6 +1529,15 @@ class SourceManager : public 
RefCountedBase<SourceManager> {
     return Filename == "<scratch space>";
   }
 
+  /// Returns whether \p Loc is located in a built-ins or command line sources.
+  bool isInPredefinedFile(SourceLocation Loc) const {
+    PresumedLoc Presumed = getPresumedLoc(Loc);
+    if (Presumed.isInvalid())
+      return false;
+    StringRef Filename(Presumed.getFilename());
+    return Filename == "<built-in>" || Filename == "<command line>";
+  }
+
   /// Returns if a SourceLocation is in a system header.
   bool isInSystemHeader(SourceLocation Loc) const {
     if (Loc.isInvalid())
diff --git a/clang/lib/ExtractAPI/ExtractAPIConsumer.cpp 
b/clang/lib/ExtractAPI/ExtractAPIConsumer.cpp
index 6f42b36bd36a4..764c345a9db99 100644
--- a/clang/lib/ExtractAPI/ExtractAPIConsumer.cpp
+++ b/clang/lib/ExtractAPI/ExtractAPIConsumer.cpp
@@ -305,8 +305,7 @@ class MacroCallback : public PPCallbacks {
 
       auto DefLoc = MI->getDefinitionLoc();
 
-      if (SM.isWrittenInBuiltinFile(DefLoc) ||
-          SM.isWrittenInCommandLineFile(DefLoc))
+      if (SM.isInPredefinedFile(DefLoc))
         continue;
 
       auto AssociatedModuleMacros = MD.getModuleMacros();
diff --git a/clang/lib/Frontend/PrintPreprocessedOutput.cpp 
b/clang/lib/Frontend/PrintPreprocessedOutput.cpp
index 2ae355fb33885..22ba4cee182af 100644
--- a/clang/lib/Frontend/PrintPreprocessedOutput.cpp
+++ b/clang/lib/Frontend/PrintPreprocessedOutput.cpp
@@ -569,8 +569,7 @@ void PrintPPOutputPPCallbacks::MacroDefined(const Token 
&MacroNameTok,
   SourceLocation DefLoc = MI->getDefinitionLoc();
   if (DirectivesOnly && !MI->isUsed()) {
     SourceManager &SM = PP.getSourceManager();
-    if (SM.isWrittenInBuiltinFile(DefLoc) ||
-        SM.isWrittenInCommandLineFile(DefLoc))
+    if (SM.isInPredefinedFile(DefLoc))
       return;
   }
   MoveToLine(DefLoc, /*RequireStartOfLine=*/true);
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 384d167cbcf88..c2bab9118234c 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -374,9 +374,8 @@ bool Preprocessor::CheckMacroName(Token &MacroNameTok, 
MacroUse isDefineUndef,
   // Macro names with reserved identifiers are accepted if built-in or passed
   // through the command line (the later may be present if -dD was used to
   // generate the preprocessed file).
-  bool IsBuiltinOrCmd = SourceMgr.isWrittenInBuiltinFile(MacroNameLoc) ||
-                        SourceMgr.isWrittenInCommandLineFile(MacroNameLoc);
-  if (!IsBuiltinOrCmd && !SourceMgr.isInSystemHeader(MacroNameLoc)) {
+  if (!SourceMgr.isInPredefinedFile(MacroNameLoc) &&
+      !SourceMgr.isInSystemHeader(MacroNameLoc)) {
     MacroDiag D = MD_NoWarn;
     if (isDefineUndef == MU_Define) {
       D = shouldWarnOnMacroDef(*this, II);
@@ -1706,8 +1705,7 @@ void Preprocessor::HandleDigitDirective(Token &DigitTok) {
     // If a filename was present, read any flags that are present.
     if (ReadLineMarkerFlags(IsFileEntry, IsFileExit, FileKind, *this))
       return;
-    if (!SourceMgr.isWrittenInBuiltinFile(DigitTok.getLocation()) &&
-        !SourceMgr.isWrittenInCommandLineFile(DigitTok.getLocation()))
+    if (!SourceMgr.isInPredefinedFile(DigitTok.getLocation()))
       Diag(StrTok, diag::ext_pp_gnu_line_directive);
 
     // Exiting to an empty string means pop to the including file, so leave

``````````

</details>


https://github.com/llvm/llvm-project/pull/139492
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