IRGen: Only emit PragmaCommentDecls if building for Windows, or LTO is enabled #35747
+15
−8
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clang::DeclContext::decls_begin()
deserializes all the pre-compiled headersimported into the current translation unit, which is expensive.
Workaround this by disabling the emission of PragmaCommentDecls unless we're
building for a Windows target, or LTO is enabled.
A better fix would be to serialize a separate index for PragmaCommentDecls
so that they can be deserialized without deserializing everything else.
I filed rdar://problem/74036099 to track the longer-term fix.
Fixes rdar://problem/73951264.