From 4159d511bca3f78fc045e31e7767d0e1cc857692 Mon Sep 17 00:00:00 2001
From: Giuliano Belinassi <gbelinassi@suse.de>
Date: Thu, 15 Aug 2024 21:56:35 -0300
Subject: [PATCH] Disable Precompiled Headers

Clang provides a feature to speedup header parsing which consists of
generating a PrecompiledHeader (.pch) file to avoid having to compile
the header multiple times if the main file needs to be reparsed
multiple times, which is the case we are interested.

However, there seems to be a bug there because the Preprocessor is
re-instantiated after generating them, loosing the __COUNT__ counter
value. So we disable it until this issue is fixed.

After testing PCH enabled vs. disabled, I noticed clang-extract is
significantly *faster* if PCH is disabled, hence disable it once
for all (1.6s vs. 1.0s for vmwgfx_execbuf case).

Signed-off-by: Giuliano Belinassi <gbelinassi@suse.de>
---
 libcextract/Passes.cpp     |  2 +-
 testsuite/includes/pch-1.c | 13 +++++++++++++
 testsuite/includes/pch-1.h | 12 ++++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 testsuite/includes/pch-1.c
 create mode 100644 testsuite/includes/pch-1.h

diff --git a/libcextract/Passes.cpp b/libcextract/Passes.cpp
index 115cd93..d701af2 100644
--- a/libcextract/Passes.cpp
+++ b/libcextract/Passes.cpp
@@ -79,7 +79,7 @@ static bool Build_ASTUnit(PassManager::Context *ctx, IntrusiveRefCntPtr<vfs::Fil
   PCHContainerOps = std::make_shared<PCHContainerOperations>();
 
   auto AU = ASTUnit::LoadFromCompilerInvocation(
-      CInvok, PCHContainerOps, Diags, FileMgr, false, CaptureDiagsKind::None, 1,
+      CInvok, PCHContainerOps, Diags, FileMgr, false, CaptureDiagsKind::None, 0,
       TU_Complete, false, false, false);
 
   if (AU == nullptr) {
diff --git a/testsuite/includes/pch-1.c b/testsuite/includes/pch-1.c
new file mode 100644
index 0000000..830ca79
--- /dev/null
+++ b/testsuite/includes/pch-1.c
@@ -0,0 +1,13 @@
+/* { dg-options "-DCE_EXTRACT_FUNCTIONS=main -DCE_NO_EXTERNALIZATION" }*/
+
+#include "pch-1.h"
+
+DEFINE_FUNCTION;
+
+int main()
+{
+  function_0();
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump "function_0" } } */
diff --git a/testsuite/includes/pch-1.h b/testsuite/includes/pch-1.h
new file mode 100644
index 0000000..6654d1f
--- /dev/null
+++ b/testsuite/includes/pch-1.h
@@ -0,0 +1,12 @@
+#define __DEFINE_FUNCTION(i) \
+  int function_ ## i (void) { \
+    return 0;\
+  }
+
+#define _DEFINE_FUNCTION(i) \
+  __DEFINE_FUNCTION(i)
+
+#define DEFINE_FUNCTION \
+  _DEFINE_FUNCTION(__COUNTER__)
+
+DEFINE_FUNCTION;