[LLD][ELF] Optimize linker script filename glob pattern matching NFC

Optimize the filename glob pattern matching in
LinkerScript::computeInputSections() and LinkerScript::shouldKeep().

Add InputFile::getNameForScript() which gets and if required caches the
Inputfile's name used for linker script matching. This avoids the
overhead of name creation that was in getFilename() in LinkerScript.cpp.

Add InputSectionDescription::matchesFile() and
SectionPattern::excludesFile() which perform the glob pattern matching
for an InputFile and make use of a cache of the previous result. As both
computeInputSections() and shouldKeep() process sections in order and
the sections of the same InputFile are contiguous, these single entry
caches can significantly speed up performance for more complex glob
patterns.

These changes have been seen to reduce link time with --gc-sections by
up to ~40% with linker scripts that contain KEEP filename glob patterns
such as "*crtbegin*.o".

Differential Revision: https://reviews.llvm.org/D87469

1 files changed, 6 insertions, 1 deletions

diff --git a/lld/include/lld/Common/Strings.h b/lld/include/lld/Common/Strings.h
index 3940d2443cd4..38d93e01c0b9 100644
--- a/lld/include/lld/Common/Strings.h
+++ b/lld/include/lld/Common/Strings.h
@@ -39,6 +39,11 @@ public:
   // Match s against this pattern, exactly if ExactMatch is true.
   bool match(llvm::StringRef s) const;
 
+  // Returns true for pattern "*" which will match all inputs.
+  bool isTrivialMatchAll() const {
+    return !ExactMatch && GlobPatternMatcher.isTrivialMatchAll();
+  }
+
 private:
   // Whether to do an exact match irregardless of the presence of wildcard
   // character.
@@ -69,7 +74,7 @@ public:
   // Add a new pattern to the existing ones to match against.
   void addPattern(SingleStringMatcher Matcher) { patterns.push_back(Matcher); }
 
-  bool empty() { return patterns.empty(); }
+  bool empty() const { return patterns.empty(); }
 
   // Match s against the patterns.
   bool match(llvm::StringRef s) const;