[clang] [clang][modules] HeaderSearch::MarkFileModuleHeader creates extra HeaderFileInfo, breaks PCM reuse (PR #89005)

[Ian Anderson via cfe-commits]

https://github.com/ian-twilightcoder created https://github.com/llvm/llvm-project/pull/89005

HeaderSearch::MarkFileModuleHeader is no longer properly checking for no-changes, and so creates a new HeaderFileInfo for every `textual header`, causes PCM use to go ballistic.

>From f45cb72cb9c70d714bdc071ac51dff1a5e11502b Mon Sep 17 00:00:00 2001
From: Ian Anderson <iana at apple.com>
Date: Tue, 16 Apr 2024 17:08:28 -0700
Subject: [PATCH] [clang][modules] HeaderSearch::MarkFileModuleHeader creates
 extra HeaderFileInfo, breaks PCM reuse

HeaderSearch::MarkFileModuleHeader is no longer properly checking for no-changes, and so creates a new HeaderFileInfo for every `textual header`, causes PCM use to go ballistic.
---
 clang/lib/Lex/HeaderSearch.cpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index 0632882b296146..9409b97ba0e64a 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -1313,6 +1313,14 @@ OptionalFileEntryRef HeaderSearch::LookupSubframeworkHeader(
 // File Info Management.
 //===----------------------------------------------------------------------===//
 
+static bool
+headerFileInfoModuleBitsMatchRole(const HeaderFileInfo *HFI,
+                                  ModuleMap::ModuleHeaderRole Role) {
+  return (HFI->isModuleHeader == ModuleMap::isModular(Role)) &&
+         (HFI->isTextualModuleHeader ==
+          ((Role & ModuleMap::TextualHeader) != 0));
+}
+
 static void mergeHeaderFileInfoModuleBits(HeaderFileInfo &HFI,
                                           bool isModuleHeader,
                                           bool isTextualModuleHeader) {
@@ -1432,7 +1440,7 @@ void HeaderSearch::MarkFileModuleHeader(FileEntryRef FE,
     if ((Role & ModuleMap::ExcludedHeader))
       return;
     auto *HFI = getExistingFileInfo(FE);
-    if (HFI && HFI->isModuleHeader)
+    if (HFI && headerFileInfoModuleBitsMatchRole(HFI, Role))
       return;
   }