I should've made longer answer even longer... Of course, source-level debugger is almost entirely useless if it can't provide values of variables; and sometimes dbx can do that, but sometimes it can't. Why don't you give it a try and see for yourself?
And why don't I copy that optimized-code topic from dbx online help here: optimized-code (topic) When programs are compiled with optimization and debugging enabled at the same time (-O -g), dbx operates in a restricted mode. The details about which compilers emit which kind of symbolic information under what circumstances is considered an unstable interface and likely to change from release to release. Source line information is available, but the code for one source line may appear in several different places for an optimized program, so stepping through a program by source line will result in the "current line" jumping around in the source file, depending on how the code was scheduled by the optimizer. Tail call optimization can result in missing stack frames when the last effective operation in a function is a call to another function. Generally, symbolic information for parameters, locals, and globals is available for optimized programs. Type information about structs, unions and C++ classes, and the types and names of locals, globals and parameters should be available. The C++ compiler will not provide symbolic type information about locals, but the C compiler will. Information about the location of parameters and locals is sometimes missing for optimized code. If dbx cannot locate a value, it will report that. Sometimes the value may disappear temporarily, so try to single-step and print it again. If you stop at the first instruction of an optimized function, dbx can print the values of parameters, because the values will be in ABI-conforming registers or stack locations. The most recent Sun compiler for SPARC machines provides the information for locating parameters and locals. Newer versions of gcc also provide this information. The most recent Sun compiler on x86 and older Sun compilers do not provide this information. Global variables may be printed and assigned to as normal, although they might have inaccurate values if the final register-to-memory store has not happened yet. The sections Inlining of Functions and Parallelization in the the Sun Studio Performance Analyzer manual contain additional information that might be helpful when debugging an optimized program. For OpenMP programs, compiling with -xopenmp=noopt instructs the compiler not to apply any optimizations, however the optimizer still processes the code in order to implement the OpenMP directives. This means there are still some of the above problems in programs that were compiled with -xopenmp=noopt. ольга крыжановская wrote: > The values and names of local variables are the data I require, so the > answer is more like 'no', right? > > Olga > > 2010/4/28 Maxim Kartashev <[email protected]>: >> Short answer is yes. >> >> Long answer is longer: >> 1. Use *latest* version of >> - compiler that generates debug info (-g -O) >> - dbx that reads and processes it >> 2. Expect certain limitations (such as inability to print arbitrary local >> variable) >> 3. See `help optimized-code' in dbx >> >> ольга крыжановская wrote: >>> Does dbx have an option to debug optimized Sun Studio code at source level? >>> >>> Olga > > > _______________________________________________ tools-compilers mailing list [email protected]
