Add debug_codegen configure flag for instr_size debugging

Makefile.config.in

@@ -198,6 +198,7 @@ MKMAINDLL=@mkmaindll@
 MKEXEDEBUGFLAG=@mkexedebugflag@
 
 RUNTIMED=@debug_runtime@
+DEBUG_CODEGEN=@debug_codegen@
 INSTRUMENTED_RUNTIME=@instrumented_runtime@
 INSTRUMENTED_RUNTIME_LIBS=@instrumented_runtime_libs@
 WITH_DEBUGGER=@with_debugger@

asmcomp/arm64/emit.mlp

@@ -1104,15 +1104,19 @@ let emit_instr_debug env i =
   `	.endif\n`
 
 let rec emit_all env lbl_start acc i =
+  let debug = Config.debug_codegen in
   match i.desc with
   | Lend ->
-     (* acc measures in units of 32-bit instructions *)
-     let sz = acc * 4 in
-     `	.ifne (. - {emit_label lbl_start}) - {emit_int sz}\n`;
-     `	.error \"Emit.instr_size: instruction length mismatch\"\n`;
-     `	.endif\n`;
+     if debug then begin
+       (* acc measures in units of 32-bit instructions *)
+       let sz = acc * 4 in
+       `	.ifne (. - {emit_label lbl_start}) - {emit_int sz}\n`;
+       `	.error \"Emit.instr_size: instruction length mismatch\"\n`;
+       `	.endif\n`;
+       end
+     else
+       ()
   | _ ->
-     let debug = false in
      if debug then emit_instr_debug env i else emit_instr env i;
      emit_all env lbl_start (acc + Size.instr_size env.f i.desc) i.next
 

configure.ac

@@ -191,6 +191,7 @@ AC_SUBST([natdynlinkopts])
 AC_SUBST([natdynlink_archive])
 AC_SUBST([cmxs])
 AC_SUBST([debug_runtime])
+AC_SUBST([debug_codegen])
 AC_SUBST([instrumented_runtime])
 AC_SUBST([instrumented_runtime_libs])
 AC_SUBST([otherlibraries])
@@ -361,6 +362,12 @@ AC_ARG_ENABLE([debug-runtime],
   [AS_HELP_STRING([--disable-debug-runtime],
     [do not build runtime with debugging support])])
 
+AC_ARG_ENABLE([debug-codegen],
+  [AS_HELP_STRING([--enable-debug-codegen],
+    [build codegen with debugging support @<:@default=no@:>@])],
+  [],
+  [enable_debug_codegen=no])
+
 AC_ARG_ENABLE([ocamldebug],
   [AS_HELP_STRING([--enable-ocamldebug],
     [build ocamldebug @<:@default=auto@:>@])],
@@ -2370,6 +2377,11 @@ AS_CASE([$enable_debug_runtime],
   [no], [debug_runtime=false],
   [debug_runtime=true])
 
+## Should the codegen with debugging support be built
+AS_CASE([$enable_debug_codegen],
+   [no], [debug_codegen=true],
+   [debug_codegen=false])
+
 ## Determine how to link with the POSIX threads library
 
 AS_CASE([$host],

utils/config.common.ml.in

@@ -123,6 +123,7 @@ let configuration_variables () =
   p_bool "supports_shared_libraries" supports_shared_libraries;
   p_bool "native_dynlink" native_dynlink;
   p_bool "naked_pointers" naked_pointers;
+  p_bool "debug_codegen" debug_codegen;
 
   p "exec_magic_number" exec_magic_number;
   p "cmi_magic_number" cmi_magic_number;

utils/config.fixed.ml

@@ -62,6 +62,7 @@ let system = "unknown"
 let asm = boot_cannot_call "the assembler"
 let asm_cfi_supported = false
 let with_frame_pointers = false
+let debug_codegen = false
 let reserved_header_bits = 0
 let ext_exe = ".ex_The boot compiler should not be using Config.ext_exe"
 let ext_obj = ".o_The boot compiler cannot process C objects"

utils/config.generated.ml.in

@@ -94,3 +94,4 @@ let flexdll_dirs = [@flexdll_dir@]
 let ar_supports_response_files = @ar_supports_response_files@
 
 let tsan = @tsan@
+let debug_codegen = @debug_codegen@

utils/config.mli

@@ -260,6 +260,9 @@ val ar_supports_response_files: bool
 val tsan : bool
 (** Whether ThreadSanitizer instrumentation is enabled *)
 
+val debug_codegen : bool
+(** Whether codegen debug information is enabled. *)
+
 (** Access to configuration values *)
 val print_config : out_channel -> unit