[flang-commits] [flang] [flang] Minor speed-up to module file parsing (PR #152178)

[via flang-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-flang-parser

Author: Peter Klausler (klausler)

<details>
<summary>Changes</summary>

Module files shouldn't ever produce parsing errors, and if they did in the case of a badly-generated module file, the compiler will notice and crash.  So we can run the parser on module files with message deferral enabled, and that saves time that would otherwise be spent generating messages on failed parsing alternatives that are discarded anyway when backtracking.  It's not a big savings (single digit percentage on overall compilation time for a big application with lots of modules), but worth doing.

---
Full diff: https://github.com/llvm/llvm-project/pull/152178.diff


1 Files Affected:

- (modified) flang/lib/Parser/parsing.cpp (+2) 


``````````diff
diff --git a/flang/lib/Parser/parsing.cpp b/flang/lib/Parser/parsing.cpp
index 93737d99567dd..ceea74766d7ea 100644
--- a/flang/lib/Parser/parsing.cpp
+++ b/flang/lib/Parser/parsing.cpp
@@ -285,6 +285,8 @@ void Parsing::Parse(llvm::raw_ostream &out) {
       .set_log(&log_);
   ParseState parseState{cooked()};
   parseState.set_inFixedForm(options_.isFixedForm).set_userState(&userState);
+  // Don't bother managing message buffers when parsing module files.
+  parseState.set_deferMessages(options_.isModuleFile);
   parseTree_ = program.Parse(parseState);
   CHECK(
       !parseState.anyErrorRecovery() || parseState.messages().AnyFatalError());

``````````

</details>


https://github.com/llvm/llvm-project/pull/152178