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[BOLT] Drop converting return profile to call cont (#129477)

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The workaround was not implemented for BAT case, and it is no longer
needed with pre-aggregated traces, alternatively, the effect can be
achieved with `infer-fall-throughs` with old pre-aggregated format
(branches + ranges).

Test Plan: updated callcont-fallthru.s
This commit is contained in:
Amir Ayupov
2025-05-06 22:21:53 -07:00
committed by GitHub
parent 9e7d529607
commit 54aa16d293
3 changed files with 7 additions and 67 deletions
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47
bolt/lib/Profile/DataAggregator.cpp
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@@ -720,23 +720,6 @@ bool DataAggregator::doBranch(uint64_t From, uint64_t To, uint64_t Count,
: isReturn(Func.disassembleInstructionAtOffset(Offset));
};
// Returns whether \p Offset in \p Func may be a call continuation excluding
// entry points and landing pads.
auto checkCallCont = [&](const BinaryFunction &Func, const uint64_t Offset) {
// No call continuation at a function start.
if (!Offset)
return false;
// FIXME: support BAT case where the function might be in empty state
// (split fragments declared non-simple).
if (!Func.hasCFG())
return false;
// The offset should not be an entry point or a landing pad.
const BinaryBasicBlock *ContBB = Func.getBasicBlockAtOffset(Offset);
return ContBB && !ContBB->isEntryPoint() && !ContBB->isLandingPad();
};
// Mutates \p Addr to an offset into the containing function, performing BAT
// offset translation and parent lookup.
//
@@ -749,8 +732,7 @@ bool DataAggregator::doBranch(uint64_t From, uint64_t To, uint64_t Count,
Addr -= Func->getAddress();
bool IsRetOrCallCont =
IsFrom ? checkReturn(*Func, Addr) : checkCallCont(*Func, Addr);
bool IsRet = IsFrom && checkReturn(*Func, Addr);
if (BAT)
Addr = BAT->translate(Func->getAddress(), Addr, IsFrom);
@@ -761,24 +743,16 @@ bool DataAggregator::doBranch(uint64_t From, uint64_t To, uint64_t Count,
NumColdSamples += Count;
if (!ParentFunc)
return std::pair{Func, IsRetOrCallCont};
return std::pair{Func, IsRet};
return std::pair{ParentFunc, IsRetOrCallCont};
return std::pair{ParentFunc, IsRet};
};
uint64_t ToOrig = To;
auto [FromFunc, IsReturn] = handleAddress(From, /*IsFrom*/ true);
auto [ToFunc, IsCallCont] = handleAddress(To, /*IsFrom*/ false);
auto [ToFunc, _] = handleAddress(To, /*IsFrom*/ false);
if (!FromFunc && !ToFunc)
return false;
// Record call to continuation trace.
if (NeedsConvertRetProfileToCallCont && FromFunc != ToFunc &&
(IsReturn || IsCallCont)) {
LBREntry First{ToOrig - 1, ToOrig - 1, false};
LBREntry Second{ToOrig, ToOrig, false};
return doTrace(First, Second, Count);
}
// Ignore returns.
if (IsReturn)
return true;
@@ -1235,21 +1209,14 @@ std::error_code DataAggregator::parseAggregatedLBREntry() {
ErrorOr<StringRef> TypeOrErr = parseString(FieldSeparator);
if (std::error_code EC = TypeOrErr.getError())
return EC;
// Pre-aggregated profile with branches and fallthroughs needs to convert
// return profile into call to continuation fall-through.
auto Type = AggregatedLBREntry::BRANCH;
if (TypeOrErr.get() == "B") {
NeedsConvertRetProfileToCallCont = true;
auto Type = AggregatedLBREntry::TRACE;
if (LLVM_LIKELY(TypeOrErr.get() == "T")) {
} else if (TypeOrErr.get() == "B") {
Type = AggregatedLBREntry::BRANCH;
} else if (TypeOrErr.get() == "F") {
NeedsConvertRetProfileToCallCont = true;
Type = AggregatedLBREntry::FT;
} else if (TypeOrErr.get() == "f") {
NeedsConvertRetProfileToCallCont = true;
Type = AggregatedLBREntry::FT_EXTERNAL_ORIGIN;
} else if (TypeOrErr.get() == "T") {
// Trace is expanded into B and [Ff]
Type = AggregatedLBREntry::TRACE;
} else {
reportError("expected T, B, F or f");
return make_error_code(llvm::errc::io_error);