[llvm-dev] [LLVMdev] Improving the quality of debug locations / DbgValueHistoryCalculator

Francois Pichet via llvm-dev llvm-dev at lists.llvm.org
Wed May 11 13:12:23 PDT 2016


Regarding the problem of debug range for optimized code.
Currently a DEBUG_VALUE will be inserted after the <def>vregX
DEBUG_VALUE are only valid until the end of the current MachineBasicBlock.
That's the main problem.
Why not simply iterate over all uses of vregX and insert an DEBUG_VALUE in
all the MachineBasicBlocks where vregX is used. (pre regalloc)

I prototyped a small pass to do that and at first it seems to improve
.debug_loc range validity and enhance the debugging experience for
optimized code.

On Wed, Aug 12, 2015 at 11:11 AM, Vikram TV via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Hi all,
> An early implementation of extending debug ranges and providing multiple
> location support is done here: http://reviews.llvm.org/D11933
> Design document:
> https://docs.google.com/document/d/1noDVWTvTWBdYdweICPBwvwyt8QvX4KHl7j3XKNSg1nE/edit?usp=sharing
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