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RemoteMirror: Project some multi-payload enums (#30357)

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* First part of multi-payload enum support

This handles multi-payload enums with fixed
layouts that don't use spare payload bits.
It includes XI calculations that allow us to
handle single-payload enums where the payload
ultimately includes a multi-payload enum
(For example, on 32-bit platforms, String uses
a multi-payload enum, so this now supports single-payload
enums carrying Strings.)
This commit is contained in:
tbkka
2020-03-11 18:48:39 -07:00
committed by GitHub
parent 80820cc7d6
commit ee36c1cc3e
6 changed files with 232 additions and 52 deletions
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47
include/swift/Reflection/ReflectionContext.h
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@@ -788,7 +788,7 @@ public:
return false;
} else {
// No payload: Payload area is reused for more cases
unsigned PayloadTag = 0;
uint32_t PayloadTag = 0;
auto PayloadTagSize = std::min(PayloadSize, decltype(PayloadSize)(sizeof(PayloadTag)));
if (!getReader().readInteger(EnumAddress, PayloadTagSize, &PayloadTag)) {
return false;
@@ -801,7 +801,50 @@ public:
}
case RecordKind::MultiPayloadEnum: {
// TODO: Support multipayload enums
// Collect basic statistics about the enum
unsigned long PayloadCaseCount = 0;
unsigned long NonPayloadCaseCount = 0;
unsigned long PayloadSize = 0;
for (auto Field : Fields) {
if (Field.TR != 0) {
PayloadCaseCount += 1;
if (Field.TI.getSize() > PayloadSize) {
PayloadSize = Field.TI.getSize();
}
} else {
NonPayloadCaseCount += 1;
}
}
if (EnumSize > PayloadSize) {
// If the compiler laid this out with a separate tag, use that.
unsigned tag = 0;
auto TagSize = EnumSize - PayloadSize;
auto TagAddress = remote::RemoteAddress(EnumAddress.getAddressData() + PayloadSize);
if (!getReader().readInteger(TagAddress, TagSize, &tag)
|| tag >= Fields.size()) {
return false;
}
if (tag < PayloadCaseCount) {
*CaseIndex = tag;
return true;
}
auto PayloadTagSize = std::min(PayloadSize, 4UL);
// Treat the tag as a page selector; payload carries the offset within the page
auto Page = tag - PayloadCaseCount;
// Zero for 32-bit because we'll never have more than one page
auto PageSize = PayloadTagSize >= 4 ? 0 : 1 << (PayloadSize * 8U);
auto PageStart = Page * PageSize;
unsigned PayloadTag;
if (!getReader().readInteger(EnumAddress, PayloadTagSize, &PayloadTag)) {
return false;
}
*CaseIndex = PageStart + PayloadTag + PayloadCaseCount;
return true;
} else {
// XXX TODO: If the payloads have common spare bits (e.g., all pointers)
// then use those to decode the case.
return false;
}
break;
}