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[BOLT] support AArch64 JUMP26 createRelocation #83531

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Merged
merged 1 commit into from
Mar 4, 2024
Merged

[BOLT] support AArch64 JUMP26 createRelocation #83531

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8 changes: 8 additions & 0 deletions bolt/lib/Core/Relocation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -381,6 +381,14 @@ static uint64_t encodeValueAArch64(uint64_t Type, uint64_t Value, uint64_t PC) {
// OP 1001_01 goes in bits 31:26 of BL.
Value = ((Value >> 2) & 0x3ffffff) | 0x94000000ULL;
break;
case ELF::R_AARCH64_JUMP26:
Value -= PC;
assert(isInt<28>(Value) &&
"only PC +/- 128MB is allowed for direct branch");
// Immediate goes in bits 25:0 of B.
// OP 0001_01 goes in bits 31:26 of B.
Value = ((Value >> 2) & 0x3ffffff) | 0x14000000ULL;
break;
}
return Value;
}
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3 changes: 3 additions & 0 deletions bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp
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Expand Up @@ -1629,6 +1629,9 @@ class AArch64MCPlusBuilder : public MCPlusBuilder {
uint64_t RelType;
if (Fixup.getKind() == MCFixupKind(AArch64::fixup_aarch64_pcrel_call26))
RelType = ELF::R_AARCH64_CALL26;
else if (Fixup.getKind() ==
MCFixupKind(AArch64::fixup_aarch64_pcrel_branch26))
RelType = ELF::R_AARCH64_JUMP26;
else if (FKI.Flags & MCFixupKindInfo::FKF_IsPCRel) {
switch (FKI.TargetSize) {
default:
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43 changes: 43 additions & 0 deletions bolt/unittests/Core/BinaryContext.cpp
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Expand Up @@ -104,6 +104,49 @@ TEST_P(BinaryContextTester, FlushPendingRelocCALL26) {
EXPECT_FALSE(memcmp(Func2Call, &Vect[12], 4)) << "Wrong forward call value\n";
}

TEST_P(BinaryContextTester, FlushPendingRelocJUMP26) {
if (GetParam() != Triple::aarch64)
GTEST_SKIP();

// This test checks that encodeValueAArch64 used by flushPendingRelocations
// returns correctly encoded values for R_AARCH64_JUMP26 relocation for both
// backward and forward branches.
//
// The offsets layout is:
// 4: func1
// 8: b func1
// 12: b func2
// 16: func2

const uint64_t Size = 20;
char *Data = new char[Size];
BinarySection &BS = BC->registerOrUpdateSection(
".text", ELF::SHT_PROGBITS, ELF::SHF_EXECINSTR | ELF::SHF_ALLOC,
(uint8_t *)Data, Size, 4);
MCSymbol *RelSymbol1 = BC->getOrCreateGlobalSymbol(4, "Func1");
ASSERT_TRUE(RelSymbol1);
BS.addRelocation(8, RelSymbol1, ELF::R_AARCH64_JUMP26, 0, 0, true);
MCSymbol *RelSymbol2 = BC->getOrCreateGlobalSymbol(16, "Func2");
ASSERT_TRUE(RelSymbol2);
BS.addRelocation(12, RelSymbol2, ELF::R_AARCH64_JUMP26, 0, 0, true);

std::error_code EC;
SmallVector<char> Vect(Size);
raw_svector_ostream OS(Vect);

BS.flushPendingRelocations(OS, [&](const MCSymbol *S) {
return S == RelSymbol1 ? 4 : S == RelSymbol2 ? 16 : 0;
});

const uint8_t Func1Call[4] = {255, 255, 255, 23};
const uint8_t Func2Call[4] = {1, 0, 0, 20};

EXPECT_FALSE(memcmp(Func1Call, &Vect[8], 4))
<< "Wrong backward branch value\n";
EXPECT_FALSE(memcmp(Func2Call, &Vect[12], 4))
<< "Wrong forward branch value\n";
}

#endif

TEST_P(BinaryContextTester, BaseAddress) {
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