In cmMakefile::PushScope, a copy of the closure of keys initialized
in the parent scope is made. In PopScope, essentially the same copy
is inserted back into the parent. That means a lot of duplication
of strings and a lot of string comparisons. None of it is needed,
because the cmDefinitions keys already provide a canonical
representation of what is initialized.
The removal of the separate container also makes the variable handling
code more easy to reason about in general.
Before this patch, configuring llvm uses 200 KiB for the VarInitStack.
Overall peak memory consumption goes from 35.5 MiB to 35.1 MiB.
Presumably the intention here is to attempt to optimize memory by not
storing what is not needed. However, all keys need to be tracked
anyway to implement initialization tracking, and this special case
gets in the way of simplifying the implementation of that.
This doesn't change any observable effects because values set
to 0 are considered not to exist by the cmDefinitions API.
d7923b82 Use std::unordered_map instead of hash_map where available.
820777af Tests: Don't rely on ordering of targets in maps.
921d74d8 AutoGen: Don't iterate over a container while populating it.
fa9eb814 cmLocalGenerator: Remove redundant path access.
1933f3d1 cmLocalGenerator: Remove redundant path conversions.
9e4b6cc2 cmState: Store computed relative paths to to current directories.
991f5e49 cmState::Snapshot: Store components for current directories.
57bdc1a2 cmState: Compute and store directory components.
61d52e6e cmListFileBacktrace: Hide the context-stack implementation detail.
a271f7f1 cmTarget: Simplify CMP0023 message loop.
f4300cd4 cmTarget: Simplify output computation.
65a42849 cmTarget: Store context in stack only if different.
9645cba3 cmListFileContext: Implement EqualityComparable.
52a8d19c cmTarget: Store only cmListFileContext for CMP0023 handling.
59ba1215 cmTarget: Remove needless iteration.
18f810a8 cmListFileContext: Sort by line before file.
e96b5d14 cmListFileContext: Implement LessThanComparable.
7eb0dfa0 cmMakefile: Use std::set::insert API to simplify CMP0054 handling.
f9785e0c cmMakefile: Simplify CMP0054 handling.
e17b5e42 cmMakefile: Add access to the top-level execution context.
1ec1bf9f if(): Test the effect of cmMakefileCall use in elseif() handling.
9b4aefad cmMakefile: Replace deques with vectors.
The backtrace will soon not be implemented in terms of a stack of
cmListFileContext objects. Keep the cmListFileContext in the API
for convenience for now.
The PushTLLCommandTrace method is called once per link item for a single
target_link_libraries command. Avoid storing copies of identical
execution contexts and rely on the uniqueness while printing output.
Our <LANG>_COMPILER and <LANG>_<TARGET_TYPE>_LINKER rule generation has
access to a specific cmTarget so the results may depend on it. Instead
generate separate rules for each target using an encoded target name.
In particular, this makes CTEST_USE_LAUNCHERS report proper target
information.
Stephen Kelly
Brad King
Kitware Robot