Debug info diet! #3350
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Debug info diet! #3350
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…(NFC-ish) Background ---------- Now that Swift AST type support in LLDB has matured, we can stop emitting DWARF type information by default to reduce compile time and ibject file size. A future commit will change -g to emit only AST type references. The full set of debug options will be -gnone -gline-tables-only -g // AST types (= everything that LLDB needs) -gdwarf-types // AST types + DWARF types (for legacy debuggers)
rdar://problem/25498103
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@swift-ci Please test |
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Would we still emit line tables in DWARF? |
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Of course! This is only about getting rid of type information that is redundant with the swift AST modules. This is quite similar to what we do in clang with -gmodules: Instead of describing the layout and structure of all types we only emit a forward-declaration of the type (and its mangled name) so it can be found in the Swift AST module. |
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@swift-ci Please test OS X platform |
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@swift-ci Please test OS X platform |
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What's in this pull request?
Now that Swift AST type support in LLDB has matured, we can stop emitting DWARF
type information by default to reduce compile time and ibject file size.
A future commit will change -g to emit only AST type references.
Note that the size difference between -gdwarf-types and -g is measurable, but not really significant in the bigger picture since DWARF is already a highly compressed format. On a Release Swift.o (x86_64 stdlib) emitting the AST types only saves ~100kb of debug info.
Resolved bug number: rdar://problem/25498103
Validation Testing
@swift-ci Please test and merge