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[MC] Simplify the logic of applying fixup for fragments, NFCI 

Replace mutiple `if else`  clauses with a `switch` clause and remove redundant checks. Before this patch, we need to add a statement like `if(!isa<MCxxxFragment>(Frag)) `  here each time we add a new kind of `MCEncodedFragment` even if it has no fixups. After this patch, we don't need to do that.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D83366
This commit is contained in:
Shengchen Kan 2020-07-09 15:06:27 +08:00
parent a60c31fd62
commit e59e39b7c4
1 changed files with 45 additions and 36 deletions
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81
llvm/lib/MC/MCAssembler.cpp
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@ -820,48 +820,57 @@ void MCAssembler::layout(MCAsmLayout &Layout) {
// Evaluate and apply the fixups, generating relocation entries as necessary.
for (MCSection &Sec : *this) {
for (MCFragment &Frag : Sec) {
// Data and relaxable fragments both have fixups. So only process
// those here.
// FIXME: Is there a better way to do this? MCEncodedFragmentWithFixups
// being templated makes this tricky.
if (isa<MCEncodedFragment>(&Frag) &&
isa<MCCompactEncodedInstFragment>(&Frag))
continue;
if (!isa<MCEncodedFragment>(&Frag) && !isa<MCCVDefRangeFragment>(&Frag) &&
!isa<MCAlignFragment>(&Frag))
continue;
ArrayRef<MCFixup> Fixups;
MutableArrayRef<char> Contents;
const MCSubtargetInfo *STI = nullptr;
if (auto *FragWithFixups = dyn_cast<MCDataFragment>(&Frag)) {
Fixups = FragWithFixups->getFixups();
Contents = FragWithFixups->getContents();
STI = FragWithFixups->getSubtargetInfo();
assert(!FragWithFixups->hasInstructions() || STI != nullptr);
} else if (auto *FragWithFixups = dyn_cast<MCRelaxableFragment>(&Frag)) {
Fixups = FragWithFixups->getFixups();
Contents = FragWithFixups->getContents();
STI = FragWithFixups->getSubtargetInfo();
assert(!FragWithFixups->hasInstructions() || STI != nullptr);
} else if (auto *FragWithFixups = dyn_cast<MCCVDefRangeFragment>(&Frag)) {
Fixups = FragWithFixups->getFixups();
Contents = FragWithFixups->getContents();
} else if (auto *FragWithFixups = dyn_cast<MCDwarfLineAddrFragment>(&Frag)) {
Fixups = FragWithFixups->getFixups();
Contents = FragWithFixups->getContents();
} else if (auto *AF = dyn_cast<MCAlignFragment>(&Frag)) {
// Process MCAlignFragment and MCEncodedFragmentWithFixups here.
switch (Frag.getKind()) {
default:
continue;
case MCFragment::FT_Align: {
MCAlignFragment &AF = cast<MCAlignFragment>(Frag);
// Insert fixup type for code alignment if the target define
// shouldInsertFixupForCodeAlign target hook.
if (Sec.UseCodeAlign() && AF->hasEmitNops()) {
getBackend().shouldInsertFixupForCodeAlign(*this, Layout, *AF);
}
if (Sec.UseCodeAlign() && AF.hasEmitNops())
getBackend().shouldInsertFixupForCodeAlign(*this, Layout, AF);
continue;
} else if (auto *FragWithFixups =
dyn_cast<MCDwarfCallFrameFragment>(&Frag)) {
Fixups = FragWithFixups->getFixups();
Contents = FragWithFixups->getContents();
} else
llvm_unreachable("Unknown fragment with fixups!");
}
case MCFragment::FT_Data: {
MCDataFragment &DF = cast<MCDataFragment>(Frag);
Fixups = DF.getFixups();
Contents = DF.getContents();
STI = DF.getSubtargetInfo();
assert(!DF.hasInstructions() || STI != nullptr);
break;
}
case MCFragment::FT_Relaxable: {
MCRelaxableFragment &RF = cast<MCRelaxableFragment>(Frag);
Fixups = RF.getFixups();
Contents = RF.getContents();
STI = RF.getSubtargetInfo();
assert(!RF.hasInstructions() || STI != nullptr);
break;
}
case MCFragment::FT_CVDefRange: {
MCCVDefRangeFragment &CF = cast<MCCVDefRangeFragment>(Frag);
Fixups = CF.getFixups();
Contents = CF.getContents();
break;
}
case MCFragment::FT_Dwarf: {
MCDwarfLineAddrFragment &DF = cast<MCDwarfLineAddrFragment>(Frag);
Fixups = DF.getFixups();
Contents = DF.getContents();
break;
}
case MCFragment::FT_DwarfFrame: {
MCDwarfCallFrameFragment &DF = cast<MCDwarfCallFrameFragment>(Frag);
Fixups = DF.getFixups();
Contents = DF.getContents();
break;
}
}
for (const MCFixup &Fixup : Fixups) {
uint64_t FixedValue;
bool IsResolved;