[PATCH 2/3] targhooks: New target hook for CTF/BTF debug info emission

[Indu Bhagat]

This patch adds a new target hook to detect if the CTF container can allow the
emission of CTF/BTF debug info at DWARF debug info early finish time. Some
backends, e.g., BPF when generating code for CO-RE usecase, may need to emit
the CTF/BTF debug info sections around the time when late DWARF debug is
finalized (dwarf2out_finish).

gcc/ChangeLog:

	* config/bpf/bpf.c (ctfc_debuginfo_early_finish_p): New definition.
	(TARGET_CTFC_DEBUGINFO_EARLY_FINISH_P): Undefine and override.
	* doc/tm.texi: Regenerated.
	* doc/tm.texi.in: Document the new hook.
	* target.def: Add a new hook.
	* targhooks.c (default_ctfc_debuginfo_early_finish_p): Likewise.
	* targhooks.h (default_ctfc_debuginfo_early_finish_p): Likewise.
---
 gcc/config/bpf/bpf.c | 14 ++++++++++++++
 gcc/doc/tm.texi      |  6 ++++++
 gcc/doc/tm.texi.in   |  2 ++
 gcc/target.def       | 10 ++++++++++
 gcc/targhooks.c      |  6 ++++++
 gcc/targhooks.h      |  2 ++
 6 files changed, 40 insertions(+)

diff --git a/gcc/config/bpf/bpf.c b/gcc/config/bpf/bpf.c
index 028013e..85f6b76 100644
--- a/gcc/config/bpf/bpf.c
+++ b/gcc/config/bpf/bpf.c
@@ -178,6 +178,20 @@ bpf_option_override (void)
 #undef TARGET_OPTION_OVERRIDE
 #define TARGET_OPTION_OVERRIDE bpf_option_override
 
+/* Return FALSE iff -mcore has been specified.  */
+
+static bool
+ctfc_debuginfo_early_finish_p (void)
+{
+  if (TARGET_BPF_CORE)
+    return false;
+  else
+    return true;
+}
+
+#undef TARGET_CTFC_DEBUGINFO_EARLY_FINISH_P
+#define TARGET_CTFC_DEBUGINFO_EARLY_FINISH_P ctfc_debuginfo_early_finish_p
+
 /* Define target-specific CPP macros.  This function in used in the
    definition of TARGET_CPU_CPP_BUILTINS in bpf.h */
 
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index a464d26..df408ee 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -10400,6 +10400,12 @@ Define this macro if GCC should produce debugging output in BTF debug
 format in response to the @option{-gbtf} option.
 @end defmac
 
+@deftypefn {Target Hook} bool TARGET_CTFC_DEBUGINFO_EARLY_FINISH_P (void)
+This target hook returns nonzero if the CTF Container can allow the
+ emission of the CTF/BTF debug info at the DWARF debuginfo early finish
+ time.
+@end deftypefn
+
 @node Floating Point
 @section Cross Compilation and Floating Point
 @cindex cross compilation and floating point
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 0b60342..6119a30 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -7020,6 +7020,8 @@ Define this macro if GCC should produce debugging output in BTF debug
 format in response to the @option{-gbtf} option.
 @end defmac
 
+@hook TARGET_CTFC_DEBUGINFO_EARLY_FINISH_P
+
 @node Floating Point
 @section Cross Compilation and Floating Point
 @cindex cross compilation and floating point
diff --git a/gcc/target.def b/gcc/target.def
index 6b4226c..67bdcba 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -4007,6 +4007,16 @@ clobbered parts of a register altering the frame register size",
  machine_mode, (int regno),
  default_dwarf_frame_reg_mode)
 
+/* Return nonzero if CTF Container can finalize the CTF/BTF emission
+   at DWARF debuginfo early finish time.  */
+DEFHOOK
+(ctfc_debuginfo_early_finish_p,
+ "This target hook returns nonzero if the CTF Container can allow the\n\
+ emission of the CTF/BTF debug info at the DWARF debuginfo early finish\n\
+ time.",
+ bool, (void),
+ default_ctfc_debuginfo_early_finish_p)
+
 /* If expand_builtin_init_dwarf_reg_sizes needs to fill in table
    entries not corresponding directly to registers below
    FIRST_PSEUDO_REGISTER, this hook should generate the necessary
diff --git a/gcc/targhooks.c b/gcc/targhooks.c
index eb51909..e38566c 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -2112,6 +2112,12 @@ default_dwarf_frame_reg_mode (int regno)
   return save_mode;
 }
 
+bool
+default_ctfc_debuginfo_early_finish_p (void)
+{
+  return true;
+}
+
 /* To be used by targets where reg_raw_mode doesn't return the right
    mode for registers used in apply_builtin_return and apply_builtin_arg.  */
 
diff --git a/gcc/targhooks.h b/gcc/targhooks.h
index f92e102..55dc443 100644
--- a/gcc/targhooks.h
+++ b/gcc/targhooks.h
@@ -255,6 +255,8 @@ extern unsigned int default_dwarf_poly_indeterminate_value (unsigned int,
 							    unsigned int *,
 							    int *);
 extern machine_mode default_dwarf_frame_reg_mode (int);
+extern bool default_ctfc_debuginfo_early_finish_p (void);
+
 extern fixed_size_mode default_get_reg_raw_mode (int);
 extern bool default_keep_leaf_when_profiled ();
 
-- 
1.8.3.1