[modules] Make the include guard optimization fire a bit more when considering
re-entering a modular header.
When we do the include guard check, we're in the visibility state for the file
with the #include; the include guard may not be visible there, but we don't
actually need it to be: if we've already parsed the submodule we're considering
entering, it's always safe to skip it.
llvm-svn: 241135
diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index 7a98f54..67a0058 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -1025,7 +1025,7 @@
bool HeaderSearch::ShouldEnterIncludeFile(Preprocessor &PP,
const FileEntry *File,
- bool isImport) {
+ bool isImport, Module *M) {
++NumIncluded; // Count # of attempted #includes.
// Get information about this file.
@@ -1050,7 +1050,11 @@
// if the macro that guards it is defined, we know the #include has no effect.
if (const IdentifierInfo *ControllingMacro
= FileInfo.getControllingMacro(ExternalLookup))
- if (PP.isMacroDefined(ControllingMacro)) {
+ // If the include file is part of a module, and we already know what its
+ // controlling macro is, then we've already parsed it and can safely just
+ // make it visible. This saves us needing to switch into the visibility
+ // state of the module just to check whether the macro is defined within it.
+ if (M || PP.isMacroDefined(ControllingMacro)) {
++NumMultiIncludeFileOptzn;
return false;
}