-gLEVEL ; support varying degrees of debuggability

1 files changed, 42 insertions, 34 deletions

diff --git a/emcc b/emcc
index 6c5b1f51..12d2c1b3 100755
--- a/emcc
+++ b/emcc
@@ -182,16 +182,31 @@ Options that are modified or new in %s include:
                            ). Note that the path must be absolute, not
                            relative.
 
-  -g                       Use debug info. Note that you need this during
-                           the last compilation phase from bitcode to
-                           JavaScript, or else we will remove it by
-                           default in -O1 and above.
-                           In -O0, line numbers wil be shown in the
-                           generated code. In -O1 and above, the optimizer
-                           removes those comments. This flag does however
-                           have the effect of disabling anything that
-                           causes name mangling or minification (closure
-                           or the registerize pass).
+  -g                       Use debug info. When compiling to bitcode,
+                           this is the same as in clang and gcc, it
+                           adds debug info to the object files. When
+                           compiling from source to JS or bitcode to JS,
+                           it is equivalent to -g3 (keep code as debuggable
+                           as possible, except for discarding LLVM
+                           debug info, so no C/C++ line numbers; use
+                           -g4 to get line number debugging info in JS).
+
+  -g<level>                When compiling from bitcode to JS, we can
+                           keep the code debuggable to different
+                           degrees. Each of these levels builds on the
+                           previous:
+
+                            -g0  Make no effort to keep code debuggable.
+                                 Will discard LLVM debug info. (default
+                                 in -O1+)
+                            -g1  Preserve (do not minify) whitespace
+                            -g2  Preserve function names
+                            -g3  Preserve variable names
+                            -g4  Preserve LLVM debug info (if -g was
+                                 used when compiling the C/C++ sources)
+                                 and show line number debug comments.
+                                 This is the highest level of debuggability.
+                                 (default in -O0)
 
   --typed-arrays <mode>    0: No typed arrays
                            1: Parallel typed arrays
@@ -303,12 +318,7 @@ Options that are modified or new in %s include:
                            archive, which is given the same name as the
                            output HTML but with suffix .data.compress
 
-  --minify <on>            0: Do not minify the generated JavaScript's
-                              whitespace (default in -O0, -O1, or if
-                              -g is used)
-                           1: Minify the generated JavaScript's
-                              whitespace (default in -O2+, assuming
-                              -g is not used)
+  --minify 0               Identical to -g1
 
   --split <size>           Splits the resulting javascript file into pieces
                            to ease debugging. This option only works if
@@ -689,13 +699,13 @@ try:
   newargs = sys.argv[1:]
 
   opt_level = 0
+  debug_level = 0
   llvm_opts = None
   llvm_lto = None
   closure = None
   js_transform = None
   pre_js = ''
   post_js = ''
-  minify_whitespace = None
   split_js_file = None
   preload_files = []
   embed_files = []
@@ -703,8 +713,6 @@ try:
   ignore_dynamic_linking = False
   shell_path = shared.path_from_root('src', 'shell.html')
   js_libraries = []
-  keep_llvm_debug = False
-  keep_js_debug = False
   bind = False
   jcache = False
   save_bc = False
@@ -769,7 +777,7 @@ try:
       newargs[i+1] = ''
     elif newargs[i].startswith('--minify'):
       check_bad_eq(newargs[i])
-      minify_whitespace = int(newargs[i+1])
+      debug_level = max(1, debug_level)
       newargs[i] = ''
       newargs[i+1] = ''
     elif newargs[i].startswith('--split'):
@@ -777,9 +785,14 @@ try:
       split_js_file = int(newargs[i+1])
       newargs[i] = ''
       newargs[i+1] = ''
-    elif newargs[i] == '-g':
-      keep_llvm_debug = True
-      keep_js_debug = True
+    elif newargs[i].startswith('-g'):
+      requested_level = newargs[i][2:] or '3'
+      try:
+        debug_level = int(requested_level)
+        assert 0 <= debug_level <= 4
+      except:
+        raise Exception('Invalid debug level: ' + newargs[i])
+      newargs[i] = '-g' # discard level for clang args
     elif newargs[i] == '--bind':
       bind = True
       newargs[i] = ''
@@ -868,8 +881,7 @@ try:
 
   if llvm_opts is None: llvm_opts = LLVM_OPT_LEVEL[opt_level]
   if llvm_lto is None: llvm_lto = opt_level >= 3
-  if opt_level <= 0: keep_llvm_debug = keep_js_debug = True # always keep debug in -O0
-  if opt_level > 0: keep_llvm_debug = False # JS optimizer wipes out llvm debug info from being visible
+  if opt_level == 0: debug_level = 4
   if closure is None and opt_level == 3: closure = True
 
   if DEBUG: start_time = time.time() # done after parsing arguments, which might affect debug state
@@ -1019,15 +1031,12 @@ try:
       logging.warning('ALIASING_FUNCTION_POINTERS is on, function pointer comparisons may be invalid across types')
 
   if shared.Settings.CORRECT_SIGNS >= 2 or shared.Settings.CORRECT_OVERFLOWS >= 2 or shared.Settings.CORRECT_ROUNDINGS >= 2:
-    keep_llvm_debug = True # must keep debug info to do line-by-line operations
+    debug_level = 4 # must keep debug info to do line-by-line operations
 
-  if (keep_llvm_debug or keep_js_debug) and closure:
+  if debug_level > 0 and closure:
     logging.warning('disabling closure because debug info was requested')
     closure = False
 
-  if minify_whitespace is None:
-    minify_whitespace = opt_level >= 2 and not keep_js_debug
-
   assert shared.LLVM_TARGET in shared.COMPILER_OPTS
   if shared.LLVM_TARGET == 'i386-pc-linux-gnu':
     shared.Settings.TARGET_X86 = 1
@@ -1398,7 +1407,7 @@ try:
 
   # Optimize, if asked to
   if not LEAVE_INPUTS_RAW:
-    link_opts = [] if keep_llvm_debug else ['-strip-debug'] # remove LLVM debug info in -O1+, since the optimizer removes it anyhow
+    link_opts = [] if debug_level >= 4 else ['-strip-debug'] # remove LLVM debug if we are not asked for it
     if llvm_opts > 0:
       if not os.environ.get('EMCC_OPTIMIZE_NORMALLY'):
         shared.Building.llvm_opt(in_temp(target_basename + '.bc'), llvm_opts)
@@ -1540,11 +1549,10 @@ try:
     logging.debug('running post-closure post-opts')
     js_optimizer_queue += ['simplifyExpressionsPost']
 
-  if (not closure or shared.Settings.ASM_JS) and shared.Settings.RELOOP and not keep_js_debug:
-    # do this if closure is not enabled (it gives similar speedups), and we do not need to keep debug info around
+  if (not closure or shared.Settings.ASM_JS) and shared.Settings.RELOOP and debug_level < 3:
     js_optimizer_queue += ['registerize']
 
-  if minify_whitespace:
+  if debug_level == 0 and opt_level > 0:
     js_optimizer_queue += ['compress']
 
   if closure and shared.Settings.ASM_JS: