Default gcc -Og to inlining key ops

Problem reported by Martin Rudalics in:
https://lists.gnu.org/r/emacs-devel/2020-04/msg00195.html
* configure.ac (DEFINE_KEY_OPS_AS_MACROS): Define if -Og.
* src/Makefile.in (KEY_OPS_CFLAGS): New macro.
(EMACS_CFLAGS): Use it.
* src/lisp.h (DEFINE_KEY_OPS_AS_MACROS): Let the gcc command line
specify it.  Remove use of undocumented INLINING macro.

3 files changed, 25 insertions, 11 deletions

diff --git a/configure.ac b/configure.ac
index 9907160482e..4e34a1cc10c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -938,6 +938,13 @@ if test "$ac_test_CFLAGS" != set; then
   esac
 fi
 
+case "$GCC, $CFLAGS " in
+  yes,*' -Og '*)
+    AC_DEFINE([DEFINE_KEY_OPS_AS_MACROS], 1,
+      [Define to 1 if key low-level operations should be C macros
+       instead of inline functions.])
+esac
+
 # gl_GCC_VERSION_IFELSE([major], [minor], [run-if-found], [run-if-not-found])
 # ---------------------------------------------------------------------------
 # If $CPP is gcc-MAJOR.MINOR or newer, then run RUN-IF-FOUND.
diff --git a/src/Makefile.in b/src/Makefile.in
index 552dd2e50ae..dfd322553b8 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -377,11 +377,14 @@ endif
 # Flags that might be in WARN_CFLAGS but are not valid for Objective C.
 NON_OBJC_CFLAGS = -Wignored-attributes -Wignored-qualifiers -Wopenmp-simd
 
+# Cajole GCC into inlining key ops even if it wouldn't normally.
+KEY_OPS_CFLAGS = $(if $(filter -Og,$(CFLAGS)),-DDEFINE_KEY_OPS_AS_MACROS)
+
 # -Demacs makes some files produce the correct version for use in Emacs.
 # MYCPPFLAGS is for by-hand Emacs-specific overrides, e.g.,
 # "make MYCPPFLAGS='-DDBUS_DEBUG'".
-EMACS_CFLAGS=-Demacs $(MYCPPFLAGS) -I. -I$(srcdir) \
-  -I$(lib) -I$(top_srcdir)/lib \
+EMACS_CFLAGS = -Demacs $(KEY_OPS_CFLAGS) $(MYCPPFLAGS) \
+  -I. -I$(srcdir) -I$(lib) -I$(top_srcdir)/lib \
   $(C_SWITCH_MACHINE) $(C_SWITCH_SYSTEM) $(C_SWITCH_X_SITE) \
   $(GNUSTEP_CFLAGS) $(CFLAGS_SOUND) $(RSVG_CFLAGS) $(IMAGEMAGICK_CFLAGS) \
   $(PNG_CFLAGS) $(LIBXML2_CFLAGS) $(DBUS_CFLAGS) \
diff --git a/src/lisp.h b/src/lisp.h
index f223814d8f3..7fc3af992e0 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -411,15 +411,19 @@ typedef EMACS_INT Lisp_Word;
 # define lisp_h_XTYPE(a) ((enum Lisp_Type) (XLI (a) & ~VALMASK))
 #endif
 
-/* When compiling via gcc -O0, define the key operations as macros, as
-   Emacs is too slow otherwise.  To disable this optimization, compile
-   with -DINLINING=false.  */
-#if (defined __NO_INLINE__ \
-     && ! defined __OPTIMIZE__ && ! defined __OPTIMIZE_SIZE__ \
-     && ! (defined INLINING && ! INLINING))
-# define DEFINE_KEY_OPS_AS_MACROS true
-#else
-# define DEFINE_KEY_OPS_AS_MACROS false
+/* When DEFINE_KEY_OPS_AS_MACROS, define key operations as macros to
+   cajole the compiler into inlining them; otherwise define them as
+   inline functions as this is cleaner and can be more efficient.
+   The default is true if the compiler is GCC-like and if function
+   inlining is disabled because the compiler is not optimizing or is
+   optimizing for size.  Otherwise the default is false.  */
+#ifndef DEFINE_KEY_OPS_AS_MACROS
+# if (defined __NO_INLINE__ \
+      && ! defined __OPTIMIZE__ && ! defined __OPTIMIZE_SIZE__)
+#  define DEFINE_KEY_OPS_AS_MACROS true
+# else
+#  define DEFINE_KEY_OPS_AS_MACROS false
+# endif
 #endif
 
 #if DEFINE_KEY_OPS_AS_MACROS