These ranges get completely jumbled by the post-ra scheduler, and it is not
really reasonable to expect it to make sense of them.
Instead, teach DwarfDebug to notice when user variables in registers are
clobbered, and terminate the ranges there.
llvm-svn: 128045
The llvm.dbg.value intrinsic refers to SSA values, not virtual registers, so we
should be able to extend the range of a value by tracking that value through
register copies. This greatly improves the debug value tracking for function
arguments that for some reason are copied to a second virtual register at the
end of the entry block.
We only extend the debug value range where its register is killed. All original
llvm.dbg.value locations are still respected.
Copies from physical registers are ignored. That should not be a problem since
the entry block already adds DBG_VALUE instructions for the virtual registers
holding the function arguments.
llvm-svn: 127912
For one, MachineBasicBlock::getFirstTerminator() doesn't understand what is
happening, and it also makes sense to have all control flow run through the
DBG_VALUE.
llvm-svn: 123277
of using a Location class with the same information.
When making a copy of a MachineOperand that was already stored in a
MachineInstr, it is necessary to clear the parent pointer on the copy. Otherwise
the register use-def lists become inconsistent.
Add MachineOperand::clearParent() to do that. An alternative would be a custom
MachineOperand copy constructor that cleared ParentMI. I didn't want to do that
because of the performance impact.
llvm-svn: 123109
Print virtual registers numbered from 0 instead of the arbitrary
FirstVirtualRegister. The first virtual register is printed as %vreg0.
TRI::NoRegister is printed as %noreg.
llvm-svn: 123107
Scan the MachineFunction for DBG_VALUE instructions, and replace them with a
data structure similar to LiveIntervals. The live range of a DBG_VALUE is
determined by propagating it down the dominator tree until a new DBG_VALUE is
found. When a DBG_VALUE lives in a register, its live range is confined to the
live range of the register's value.
LiveDebugVariables runs before coalescing, so DBG_VALUEs are not artificially
extended when registers are joined.
The missing half will recreate DBG_VALUE instructions from the intervals when
register allocation is complete.
The pass is disabled by default. It can be enabled with the temporary command
line option -live-debug-variables.
llvm-svn: 120636
This analysis is going to run immediately after LiveIntervals. It will stay
alive during register allocation and keep track of user variables mentioned in
DBG_VALUE instructions.
When the register allocator is moving values between registers and the stack, it
is very hard to keep track of DBG_VALUE instructions. We usually get it wrong.
This analysis maintains a data structure that makes it easy to update DBG_VALUE
instructions.
llvm-svn: 120385
