Disable partial inlining for runtime/str.c (#2662)

* Disable partial inlining for runtime/str.c

* Propagate the flag from configure

* Regenerate configure

Author: mshinwell

ocaml/Makefile

@@ -1019,6 +1019,10 @@ $(DEPDIR)/$(RUNTIME_DIR)/%.npic.$(D): OC_CPPFLAGS += $(OC_NATIVE_CPPFLAGS)
 # https://www.intel.co.uk/content/www/uk/en/support/articles/000055650/processors.html
 $(RUNTIME_DIR)/major_gc.%.$(O): OC_CFLAGS += $(INTEL_JCC_BUG_CFLAGS)
 
+# Partial inlining on (at least) caml_string_compare seems to produce
+# worse code.
+$(RUNTIME_DIR)/str.%.$(O): OC_CFLAGS += $(NO_PARTIAL_INLINING_CFLAGS)
+
 ## Compilation of runtime C files
 
 # The COMPILE_C_FILE macro below receives as argument the pattern

ocaml/Makefile.config.in

@@ -219,6 +219,7 @@ WITH_PROFINFO=@profinfo@
 PROFINFO_WIDTH=@profinfo_width@
 HEADER_RESERVED_BITS=@reserved_header_bits@
 CUSTOM_OPS_STRUCT_SIZE=@custom_ops_struct_size@
+NO_PARTIAL_INLINING_CFLAGS=@no_partial_inlining_cflags@
 LIBUNWIND_AVAILABLE=@libunwind_available@
 LIBUNWIND_INCLUDE_FLAGS=@libunwind_include_flags@
 LIBUNWIND_LINK_FLAGS=@libunwind_link_flags@

ocaml/configure

@@ -219,6 +219,7 @@ AC_SUBST([reserved_header_bits])
 AC_SUBST([profinfo])
 AC_SUBST([profinfo_width])
 AC_SUBST([custom_ops_struct_size])
+AC_SUBST([no_partial_inlining_cflags])
 AC_SUBST([frame_pointers])
 AC_SUBST([cpp_mangling])
 AC_SUBST([flambda])
@@ -2222,6 +2223,12 @@ AC_DEFINE_UNQUOTED([HEADER_RESERVED_BITS], [$reserved_header_bits])
 AC_DEFINE_UNQUOTED([PROFINFO_WIDTH], [$profinfo_width])
 AS_IF([$profinfo], [AC_DEFINE([WITH_PROFINFO])])
 
+# Only gcc supports -fno-partial-inlining
+AS_CASE([$ocaml_cv_cc_vendor],
+  [gcc-*],
+    [no_partial_inlining_cflags="-fno-partial-inlining"],
+  [no_partial_inlining_cflags=""])
+
 AC_DEFINE_UNQUOTED([CUSTOM_OPS_STRUCT_SIZE], [$custom_ops_struct_size])
 
 AS_IF([test x"$enable_installing_bytecode_programs" = "xno"],