Before this change, stepping through the code
1 foo(x,
2 f(a)
3 f(b)
4 )
would visit the code in the order 2, 3, 4, with the function call
being on line 4. After this patch the order is 2, 3, 1 with the
function call being on line 1. This is both closer to what clang
generates for simialar C code and more useful to the programmer since
it is easier to understand which function is being called in a nested
expression.
rdar://problem/35430708
This commit changes how inline information is stored in SILDebugScope
from a tree to a linear chain of inlined call sites (similar to what
LLVM is using). This makes creating inlined SILDebugScopes slightly
more expensive, but makes lowering SILDebugScopes into LLVM metadata
much faster because entire inlined-at chains can now be cached. This
means that SIL is no longer preserve the inlining history (i.e., ((a
was inlined into b) was inlined into c) is represented the same as (a
was inlined into (b was inlined into c)), but this information was not
used by anyone.
On my late 2012 i7 iMac, this saves about 4 seconds when compiling the
RelWithDebInfo x86_64 swift standard library — or 40% of IRGen time.
rdar://problem/28311051
Instead of appending a character for each substitution, we now prefix the substitution with the repeat count, e.g.
AbbbbB -> A5B
The same is done for known-type substitutions, e.g.
SiSiSi -> S3i
This significantly shrinks mangled names which contain large lists of the same type, like
func foo(_ x: (Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int))
rdar://problem/30707433
inlined-at chain.
The previous implementation was only correct for cases where the inliner
inlined bottom-up in the call graph, which happened to cover the majority
of all cases.
rdar://problem/24462475
