Bug 152703 – offlineasm: Emit Dwarf2 file and location directives to allow for debugging .asm files

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Michael Saboff]

If the offline assembler added .file and .loc Dwarf2 directives, we can do source level debugging of the LLInt .asm files.

For example:

(lldb)
Process 55150 stopped
* thread #1: tid = 0xc9de2a, 0x0000000100ada5cf JavaScriptCore`llint_entry + 7403 at LowLevelInterpreter64.asm:796, queue = 'com.apple.main-thread', stop reason = step over
    frame #0: 0x0000000100ada5cf JavaScriptCore`llint_entry + 7403 at LowLevelInterpreter64.asm:796
   793 	    loadq [cfr, t0, 8], t1
   794 	    bqb t1, tagTypeNumber, .slow
   795 	    arithmeticOperation(t1, .slow)
-> 796 	    orq tagTypeNumber, t1
   797 	    storeq t1, [cfr, t0, 8]
   798 	    dispatch(2)
   799 	
(lldb) n
Process 55150 stopped
* thread #1: tid = 0xc9de2a, 0x0000000100ada5d2 JavaScriptCore`llint_entry + 7406 at LowLevelInterpreter64.asm:797, queue = 'com.apple.main-thread', stop reason = step over
    frame #0: 0x0000000100ada5d2 JavaScriptCore`llint_entry + 7406 at LowLevelInterpreter64.asm:797
   794 	    bqb t1, tagTypeNumber, .slow
   795 	    arithmeticOperation(t1, .slow)
   796 	    orq tagTypeNumber, t1
-> 797 	    storeq t1, [cfr, t0, 8]
   798 	    dispatch(2)
   799 	
   800 	.slow:
(lldb) bt 6
* thread #1: tid = 0xc9de2a, 0x0000000100ada5d2 JavaScriptCore`llint_entry + 7406 at LowLevelInterpreter64.asm:797, queue = 'com.apple.main-thread', stop reason = step over
  * frame #0: 0x0000000100ada5d2 JavaScriptCore`llint_entry + 7406 at LowLevelInterpreter64.asm:797
    frame #1: 0x0000001000000001
    frame #2: 0x0000000100adf138 JavaScriptCore`llint_entry + 26708 at LowLevelInterpreter.asm:726
    frame #3: 0x0000000100ad86ce JavaScriptCore`vmEntryToJavaScript + 334 at LowLevelInterpreter64.asm:249
    frame #4: 0x000000010090ec35 JavaScriptCore`JSC::JITCode::execute(this=0x00000001069a2258, vm=0x0000000106c01000, protoCallFrame=0x00007fff5fbfa898) + 213 at JITCode.cpp:80
    frame #5: 0x00000001008d6147 JavaScriptCore`JSC::Interpreter::execute(this=0x0000000103bf8548, program=0x0000000106896900, callFrame=0x00000001068a3740, thisObj=0x00000001068c9ac0) + 4471 at Interpreter.cpp:975
(lldb) 

This change is dependent on fixing a bug in the Clang toolchain.  That bug is tracked in <rdar://problem/22690666>

[Michael Saboff]

Created attachment 268208 [details]
Patch

This patch cannot be landed or enabled without the fix needed for Clang to support multiple .file directives from inlined assembly.

[Michael Saboff]

(In reply to comment #1)
> Created attachment 268208 [details]
> Patch
> 
> This patch cannot be landed or enabled without the fix needed for Clang to
> support multiple .file directives from inlined assembly.

This patch could be landed with $enableDebugAnnotations = false in config.rb.

[Geoffrey Garen]

Comment on attachment 268208 [details]
Patch

Generating ../../DerivedSources/JavaScriptCore/LowLevelInterpreterWin.asm
  Assembling C:\cygwin\home\buildbot\WebKit\WebKitBuild\Release\DerivedSources\JavaScriptCore\LowLevelInterpreterWin.asm...
reterWin.asm(5): error A2071: initializer magnitude too large for specified size [C:\cygwin\home\buildbot\WebKit\WebKitBuild\Release\Source\JavaScriptCore\JavaScriptCore.vcxproj]
MASM : error A2109: only white space or comment can follow backslash [C:\cygwin\home\buildbot\WebKit\WebKitBuild\Release\Source\JavaScriptCore\JavaScriptCore.vcxproj]
reterWin.asm(7): error A2071: initializer magnitude too large for specified size [C:\cygwin\home\buildbot\WebKit\WebKitBuild\Release\Source\JavaScriptCore\JavaScriptCore.vcxproj]
MASM : error A2109: only white space or comment can follow backslash [C:\cygwin\home\buildbot\WebKit\WebKitBuild\Release\Source\JavaScriptCore\JavaScriptCore.vcxproj]
reterWin.asm(9): error A2071: initializer magnitude too large for specified size [C:\cygwin\home\buildbot\WebKit\WebKitBuild\Release\Source\JavaScriptCore\JavaScriptCore.vcxproj]
MASM : error A2109: only white space or comment can follow backslash [C:\cygwin\home\buildbot\WebKit\WebKitBuild\Release\Source\JavaScriptCore\JavaScriptCore.vcxproj]
reterWin.asm(11): error A2071: initializer magnitude too large for specified size [C:\cygwin\home\buildbot\WebKit\WebKitBuild\Release\Source\JavaScriptCore\JavaScriptCore.vcxproj]
MASM : error A2109: only white space or comment can follow backslash [C:\cygwin\home\buildbot\WebKit\WebKitBuild\Release\Source\JavaScriptCore\JavaScriptCore.vcxproj]

[Michael Saboff]

Created attachment 268246 [details]
Updated patch

Fixed windows issue.

Turned off debug annotations.  To be turned on when clang bug is fixed.

[Csaba Osztrogonác]

Comment on attachment 268246 [details]
Updated patch

View in context: https://bugs.webkit.org/attachment.cgi?id=268246&action=review

> Source/JavaScriptCore/offlineasm/arm64.rb:1
> +# Copyright (C) 2011, 2012, 2014, 2015, 2106 Apple Inc. All rights reserved.

typo: 2106 -> 2016

> Source/JavaScriptCore/offlineasm/arm.rb:1
> +# Copyright (C) 2011, 2012, 2015, 2106 Apple Inc. All rights reserved.

ditto

[Michael Saboff]

(In reply to comment #5)
> Comment on attachment 268246 [details]
> Updated patch
> 
> View in context:
> https://bugs.webkit.org/attachment.cgi?id=268246&action=review
> 
> > Source/JavaScriptCore/offlineasm/arm64.rb:1
> > +# Copyright (C) 2011, 2012, 2014, 2015, 2106 Apple Inc. All rights reserved.
> 
> typo: 2106 -> 2016
> 
> > Source/JavaScriptCore/offlineasm/arm.rb:1
> > +# Copyright (C) 2011, 2012, 2015, 2106 Apple Inc. All rights reserved.
> 
> ditto

Just thinking ahead ;)

Fixed locally.

[Mark Lam]

Comment on attachment 268246 [details]
Updated patch

View in context: https://bugs.webkit.org/attachment.cgi?id=268246&action=review

r=me

>>> Source/JavaScriptCore/offlineasm/arm64.rb:1
>>> +# Copyright (C) 2011, 2012, 2014, 2015, 2106 Apple Inc. All rights reserved.
>> 
>> typo: 2106 -> 2016
> 
> Just thinking ahead ;)
> 
> Fixed locally.

FYI, for brevity, you can use "2014-2016" instead of "2014, 2015, 2016".

[Michael Saboff]

Committed r196541: <http://trac.webkit.org/changeset/196541>