[lldb-dev] Problems printing local variables with LLDB

[Greg Clayton]

File a compiler bug with your source file. At -O0 you should always have access to your variables. LLDB is just showing you what the compiler tells us.

Greg Clayton

> On May 27, 2014, at 2:11 PM, Christian Schafmeister <chris.schaf at verizon.net> wrote:
> 
> 
> How do I ensure that I can print all local variables from within LLDB?
> 
> When I use LLDB, more than half the time when I try to print a local variable I get an error and “frame variable” shows the variable as being <variable not available>
> 
> I’m compiling all of my source with “-O0 -g”.   
> 
> I have not been able to create a small test case where this happens - all of my attempts at small test cases print local variables just fine.
> 
> Here is a typical compiler invocation for my debug build:
> 
> "clang++" -x c++ -O0 -g -Warray-bounds -Wgnu-array-member-paren-init -Wno-deprecated-register -mmacosx-version-min=10.7 -fvisibility=default -std=c++11 -stdlib=libc++ -DCONFIG_VAR_COOL -DDEBUG_ASSERTS -DDEBUG_MPS_AMS_POOL -DEXPAT -DINCLUDED_FROM_CLASP -DINHERITED_FROM_SRC -DREADLINE -DUSE_BOEHM -D_ADDRESS_MODEL_64 -D_DEBUG_BUILD -D_TARGET_OS_DARWIN -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I"../../src" -I"../../src/core" -I"../../src/core/bin/boehm/clang-darwin-4.2.1/debug/link-static" -I"/Library/Frameworks/EPD64.framework/Versions/7.2/include/python2.7" -I"/Users/meister/Development/cando/clasp/build/cando.app/Contents/Resources/externals/common/include" -I"/Users/meister/Development/cando/clasp/build/cando.app/Contents/Resources/externals/release/include" -c -o "../../src/core/bin/boehm/clang-darwin-4.2.1/debug/link-static/evaluator.o" "../../src/core/evaluator.cc"
> 
> 
> Here’s an example of what I run into all the time with LLDB:
> 
> frame #12: 0x000000010119800e clasp_boehm_d`core::SpecialForm_O::evaluate(mem::smart_ptr<core::Cons_O>, mem::smart_ptr<core::Environment_O>) + 542 at /Users/meister/Development/cando/clasp/src/core/../../src/core/specialForm.cc:41
>    38  	    T_mv SpecialForm_O::evaluate( Cons_sp args, Environment_sp environment )
>    39  	    {_OF();
>    40  		ASSERTP(this->_fptr!=NULL,"Functoid can not be NULL");
> -> 41  		return (this->_fptr)(args,environment);
>    42  	    }
>    43  	
>    44  	
> (lldb) frame variable
> frame variable
> (core::SpecialForm_O *) this = 0x00000001067d4008
> (core::Cons_sp) args = <variable not available>
> 
> (core::Environment_sp) environment = <variable not available>
> 
> (lldb) print args
> print args
> error: Couldn't materialize struct: size of variable args (8) disagrees with the ValueObject's size (0)
> Errored out in Execute, couldn't PrepareToExecuteJITExpression
> (lldb) 
> 
> 
> 
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