The effect of this tiny change is that local variables will be described
by llvm.dbg.values, which will get lowered into an accurate location list
instead of a stack slot that is valid for the entire scope of the variable.
This means the debugger can now accurately track the liveness of variables
knowing exactly when they are initialized and when there values go away.
Function arguments are still kept in stack slots because (1) they are
already initialized at the function entry and (2) LLDB really needs self
to be available at all times for the expression evaluator.
This was made possible by recent advancements in LLVM such as the live
debug variables pass and various related bugfixes.
<rdar://problem/15746520>
The effect of this tiny change is that local variables will be described
by llvm.dbg.values, which will get lowered into an accurate location list
instead of a stack slot that is valid for the entire scope of the variable.
This means the debugger can now accurately track the liveness of variables
knowing exactly when they are initialized and when there values go away.
Function arguments are still kept in stack slots because (1) they are
already initialized at the function entry and (2) LLDB really needs self
to be available at all times for the expression evaluator.
This was made possible by recent advancements in LLVM such as the live
debug variables pass and various related bugfixes.
<rdar://problem/15746520>
And include some supplementary mangling changes:
- Give the first generic param (depth=0, index=0) a single character mangling. Even after removing the self type from method declaration types, 'Self' still shows up very frequently in protocol requirement signatures.
- Fix the mangling of generic parameter counts to elide the count when there's only one parameter at the starting depth of the mangling.
Together these carve another 154KB out of a debug standard library. There's some awkwardness in demangled strings that I'll clean up in subsequent commits; since decl types now only mangle the number of generic params at their own depth, it's context-dependent what depths those represent, which we get wrong now. Currying markers are also wrong, but since free function currying is going away, we can mangle the partial application thunks in different ways.
Swift SVN r32896
