From d3f586ec50d3d502e0727e8307ae76770fdaee79 Mon Sep 17 00:00:00 2001
From: David Faust <david.faust@oracle.com>
Date: Thu, 30 May 2024 14:06:27 -0700
Subject: ctf, btf: restructure CTF/BTF emission

This commit makes some structural changes to the CTF/BTF debug info
emission.  In particular:

 a) CTF is new always fully generated and emitted before any
    BTF-related procedures are run.  This means that BTF-related
    functions can change, even irreversibly, the shared in-memory
    representation used by the two formats without issue.

 b) BTF generation has fewer entry points, and is cleanly divided
    into early_finish and finish.

 c) BTF is now always emitted at finish (called from dwarf2out_finish),
    for all targets in non-LTO builds, rather than being emitted at
    early_finish for targets other than BPF CO-RE.  In LTO builds,
    BTF is emitted at early_finish as before.

    Note that this change alone does not alter the contents of BTF at
    all, regardless of whether it would have previously been emitted at
    early_finish or finish, because the calculation of the BTF to be
    emitted is not moved by this patch, only the write-out.

The changes are transparent to both CTF and BTF emission.

gcc/
	* btfout.cc (btf_init_postprocess): Rename to...
	(btf_early_finish): ...this.
	(btf_output): Rename to...
	(btf_finish): ...this.
	* ctfc.h: Analogous changes.
	* dwarf2ctf.cc (ctf_debug_early_finish): Conditionally call
	btf_early_finish, or ctf_finalize as appropriate.  Emit BTF
	here for LTO builds.
	(ctf_debug_finish): Always call btf_finish here if generating
	BTF info in non-LTO builds.
	(ctf_debug_finalize, ctf_debug_init_postprocess): Delete.
	* dwarf2out.cc (dwarf2out_early_finish): Remove call to
	ctf_debug_init_postprocess.
---
 gcc/btfout.cc | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

(limited to 'gcc/btfout.cc')

diff --git a/gcc/btfout.cc b/gcc/btfout.cc
index 07f066a..d5e9f3b 100644
--- a/gcc/btfout.cc
+++ b/gcc/btfout.cc
@@ -1491,6 +1491,34 @@ btf_finalize (void)
   tu_ctfc = NULL;
 }
 
+/* Initial entry point of BTF generation, called at early_finish () after
+   CTF information has possibly been output.  Translate all CTF information
+   to BTF, and do any processing that must be done early, such as creating
+   BTF_KIND_FUNC records.  */
+
+void
+btf_early_finish (void)
+{
+  btf_init_postprocess ();
+}
+
+/* Late entry point for BTF generation, called from dwarf2out_finish ().
+   Complete and emit BTF information.  */
+
+void
+btf_finish (const char * filename)
+{
+  btf_output (filename);
+
+  /* If compiling for BPF with CO-RE info, we cannot deallocate until after the
+     contents of the .BTF.ext section are finalized, which happens very late in
+     BPF backend.  Therefore, the deallocation (i.e. btf_finalize ()) is delayed
+     until TARGET_ASM_FILE_END for BPF CO-RE.  */
+  if (!btf_with_core_debuginfo_p ())
+    btf_finalize ();
+}
+
+
 /* Traversal function for all BTF_KIND_FUNC type records.  */
 
 bool
-- 
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