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[ABI] Optimize out the witness table pattern for resilient conformances.

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Resilient conformances now put all witnesses into the resilient witness
table, so optimize away the witness table pattern for such cases. Teach
the runtime to fill in the protocol conformance descriptor, because that’s
the only bit of real information that would be in the pattern.

This is a minor optimization enabled by rdar://problem/46282080.
This commit is contained in:
Doug Gregor
2018-12-03 20:16:18 -08:00
parent c0519c7185
commit f2dd852f94
7 changed files with 45 additions and 41 deletions
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18
stdlib/public/runtime/Metadata.cpp
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@@ -4069,12 +4069,18 @@ WitnessTableCacheEntry::allocate(
// Advance the address point; the private storage area is accessed via
// negative offsets.
auto table = fullTable + privateSizeInWords;
auto pattern = reinterpret_cast<void * const *>(
&*conformance->getWitnessTablePattern());
// Fill in the provided part of the requirements from the pattern.
for (size_t i = 0, e = numPatternWitnesses; i < e; ++i) {
table[i] = pattern[i];
if (auto pattern =
reinterpret_cast<void * const *>(
&*conformance->getWitnessTablePattern())) {
// Fill in the provided part of the requirements from the pattern.
for (size_t i = 0, e = numPatternWitnesses; i < e; ++i) {
table[i] = pattern[i];
}
} else {
// Put the conformance descriptor in place. Instantiation will fill in the
// rest.
assert(numPatternWitnesses == 0);
table[0] = (void *)conformance;
}
// Copy any instantiation arguments that correspond to conditional