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[BOLT] Use ULEB128 encoding for PIE/DSO exception tables #116911

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Merged
merged 2 commits into from
Nov 20, 2024
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[BOLT] Use ULEB128 encoding for PIE/DSO exception tables #116911

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0c3cda3
[BOLT] Use ULEB128 encoding for PIE/DSO exception tables
maksfb Nov 20, 2024
04fb452
fixup! [BOLT] Use ULEB128 encoding for PIE/DSO exception tables
maksfb Nov 20, 2024
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23 changes: 15 additions & 8 deletions bolt/lib/Core/BinaryEmitter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -959,9 +959,9 @@ void BinaryEmitter::emitLSDA(BinaryFunction &BF, const FunctionFragment &FF) {
if (NeedsLPAdjustment)
LPOffsetExpr = MCBinaryExpr::createAdd(
LPOffsetExpr, MCConstantExpr::create(1, *BC.Ctx), *BC.Ctx);
Streamer.emitValue(LPOffsetExpr, 4);
Streamer.emitULEB128Value(LPOffsetExpr);
} else {
Streamer.emitIntValue(0, 4);
Streamer.emitULEB128IntValue(0);
}
};
}
Expand All @@ -976,10 +976,12 @@ void BinaryEmitter::emitLSDA(BinaryFunction &BF, const FunctionFragment &FF) {
Streamer.emitLabel(TTBaseRefLabel);
}

// Emit the landing pad call site table. We use signed data4 since we can emit
// a landing pad in a different part of the split function that could appear
// earlier in the address space than LPStart.
Streamer.emitIntValue(dwarf::DW_EH_PE_sdata4, 1);
// Emit encoding of entries in the call site table. The format is used for the
// call site start, length, and corresponding landing pad.
if (BC.HasFixedLoadAddress)
Streamer.emitIntValue(dwarf::DW_EH_PE_sdata4, 1);
else
Streamer.emitIntValue(dwarf::DW_EH_PE_uleb128, 1);

MCSymbol *CSTStartLabel = BC.Ctx->createTempSymbol("CSTStart");
MCSymbol *CSTEndLabel = BC.Ctx->createTempSymbol("CSTEnd");
Expand All @@ -996,8 +998,13 @@ void BinaryEmitter::emitLSDA(BinaryFunction &BF, const FunctionFragment &FF) {

// Start of the range is emitted relative to the start of current
// function split part.
Streamer.emitAbsoluteSymbolDiff(BeginLabel, StartSymbol, 4);
Streamer.emitAbsoluteSymbolDiff(EndLabel, BeginLabel, 4);
if (BC.HasFixedLoadAddress) {
Streamer.emitAbsoluteSymbolDiff(BeginLabel, StartSymbol, 4);
Streamer.emitAbsoluteSymbolDiff(EndLabel, BeginLabel, 4);
} else {
Streamer.emitAbsoluteSymbolDiffAsULEB128(BeginLabel, StartSymbol);
Streamer.emitAbsoluteSymbolDiffAsULEB128(EndLabel, BeginLabel);
}
emitLandingPad(CallSite.LP);
Streamer.emitULEB128IntValue(CallSite.Action);
}
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