This patch adds the -Xclang option
"-fexperimental-debug-variable-locations" and same LLVM CodeGen option,
to pick which variable location tracking solution to use.
Right now all the switch does is pick which LiveDebugValues
implementation to use, the normal VarLoc one or the instruction
referencing one in rGae6f78824031. Over time, the aim is to add fragments
of support in aid of the value-tracking RFC:
http://lists.llvm.org/pipermail/llvm-dev/2020-February/139440.html
also controlled by this command line switch. That will slowly move
variable locations to be defined by an instruction calculating a value,
and a DBG_INSTR_REF instruction referring to that value. Thus, this is
going to grow into a "use the new kind of variable locations" switch,
rather than just "use the new LiveDebugValues implementation".
Differential Revision: https://reviews.llvm.org/D83048
This patch imports the instruction-referencing implementation of
LiveDebugValues proposed here:
http://lists.llvm.org/pipermail/llvm-dev/2020-June/142368.html
The new implementation is unreachable in this patch, it's the next patch
that enables it behind a command line switch. Briefly, rather than
tracking variable locations by just their location as the 'VarLoc'
implementation does, this implementation does it by value:
* Each value defined in a function is numbered, and propagated through
dataflow,
* Each DBG_VALUE reads a machine value number from a machine location,
* Variable _values_ are propagated through dataflow,
* Variable values are translated back into locations, DBG_VALUEs
inserted to specify where those locations are.
The ultimate aim of this is to enable referring to variable values
throughout post-isel code, rather than locations. Those patches will
build on top of this new LiveDebugValues implementation in later patches
-- it can't be done with the VarLoc implementation as we don't have
value information, only locations.
Differential Revision: https://reviews.llvm.org/D83047
This patch renames the current LiveDebugValues class to "VarLocBasedLDV"
and removes the pass-registration code from it. It creates a separate
LiveDebugValues class that deals with pass registration and management,
that calls through to VarLocBasedLDV::ExtendRanges when
runOnMachineFunction is called. This is done through the "LDVImpl"
abstract class, so that a future patch can install the new
instruction-referencing LiveDebugValues implementation and have it
picked at runtime.
No functional change is intended, just shuffling responsibilities.
Differential Revision: https://reviews.llvm.org/D83046
This is a pure file move of LiveDebugValues.cpp ahead of the pass being
refactored, with an experimental new implementation to follow.
The motivation for these changes can be found here:
http://lists.llvm.org/pipermail/llvm-dev/2020-June/142368.html
And the other related changes can be found in the phabricator stack for
this revision:
Differential Revision: https://reviews.llvm.org/D83304
Simon Pilgrim