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https://github.com/c64scene-ar/llvm-6502.git
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Simplify handling of relocations
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28090 91177308-0d34-0410-b5e6-96231b3b80d8
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9e062ed516
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@ -57,6 +57,8 @@ namespace {
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void emitExternalSymbolAddress(const char *ES, bool isPCRelative,
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bool isTailCall);
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void emitDisplacementField(const MachineOperand *RelocOp, int DispVal);
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void emitRegModRMByte(unsigned ModRMReg, unsigned RegOpcodeField);
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void emitSIBByte(unsigned SS, unsigned Index, unsigned Base);
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void emitConstant(unsigned Val, unsigned Size);
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@ -211,19 +213,39 @@ void Emitter::emitConstant(unsigned Val, unsigned Size) {
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}
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}
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/// isDisp8 - Return true if this signed displacement fits in a 8-bit
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/// sign-extended field.
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static bool isDisp8(int Value) {
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return Value == (signed char)Value;
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}
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void Emitter::emitDisplacementField(const MachineOperand *RelocOp,
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int DispVal) {
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// If this is a simple integer displacement that doesn't require a relocation,
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// emit it now.
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if (!RelocOp) {
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emitConstant(DispVal, 4);
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return;
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}
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// Otherwise, this is something that requires a relocation. Emit it as such
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// now.
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if (RelocOp->isGlobalAddress()) {
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emitGlobalAddressForPtr(RelocOp->getGlobal(), RelocOp->getOffset());
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} else {
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assert(0 && "Unknown value to relocate!");
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}
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}
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void Emitter::emitMemModRMByte(const MachineInstr &MI,
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unsigned Op, unsigned RegOpcodeField) {
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const MachineOperand &Op3 = MI.getOperand(Op+3);
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GlobalValue *GV = 0;
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int DispVal = 0;
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const MachineOperand *DispForReloc = 0;
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// Figure out what sort of displacement we have to handle here.
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if (Op3.isGlobalAddress()) {
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GV = Op3.getGlobal();
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DispVal = Op3.getOffset();
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DispForReloc = &Op3;
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} else if (Op3.isConstantPoolIndex()) {
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DispVal += MCE.getConstantPoolEntryAddress(Op3.getConstantPoolIndex());
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DispVal += Op3.getOffset();
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@ -244,27 +266,21 @@ void Emitter::emitMemModRMByte(const MachineInstr &MI,
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if (BaseReg == 0) { // Just a displacement?
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// Emit special case [disp32] encoding
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MCE.emitByte(ModRMByte(0, RegOpcodeField, 5));
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if (GV)
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emitGlobalAddressForPtr(GV, DispVal);
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else
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emitConstant(DispVal, 4);
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emitDisplacementField(DispForReloc, DispVal);
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} else {
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unsigned BaseRegNo = getX86RegNum(BaseReg);
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if (GV) {
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// Emit the most general non-SIB encoding: [REG+disp32]
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MCE.emitByte(ModRMByte(2, RegOpcodeField, BaseRegNo));
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emitGlobalAddressForPtr(GV, DispVal);
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} else if (DispVal == 0 && BaseRegNo != N86::EBP) {
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if (!DispForReloc && DispVal == 0 && BaseRegNo != N86::EBP) {
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// Emit simple indirect register encoding... [EAX] f.e.
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MCE.emitByte(ModRMByte(0, RegOpcodeField, BaseRegNo));
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} else if (isDisp8(DispVal)) {
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} else if (!DispForReloc && isDisp8(DispVal)) {
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// Emit the disp8 encoding... [REG+disp8]
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MCE.emitByte(ModRMByte(1, RegOpcodeField, BaseRegNo));
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emitConstant(DispVal, 1);
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} else {
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// Emit the most general non-SIB encoding: [REG+disp32]
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MCE.emitByte(ModRMByte(2, RegOpcodeField, BaseRegNo));
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emitConstant(DispVal, 4);
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emitDisplacementField(DispForReloc, DispVal);
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}
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}
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@ -278,8 +294,8 @@ void Emitter::emitMemModRMByte(const MachineInstr &MI,
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// MOD=0, BASE=5, to JUST get the index, scale, and displacement.
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MCE.emitByte(ModRMByte(0, RegOpcodeField, 4));
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ForceDisp32 = true;
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} else if (GV) {
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// Emit the normal disp32 encoding...
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} else if (DispForReloc) {
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// Emit the normal disp32 encoding.
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MCE.emitByte(ModRMByte(2, RegOpcodeField, 4));
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ForceDisp32 = true;
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} else if (DispVal == 0 && BaseReg != X86::EBP) {
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@ -314,13 +330,10 @@ void Emitter::emitMemModRMByte(const MachineInstr &MI,
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}
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// Do we need to output a displacement?
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if (DispVal != 0 || ForceDisp32 || ForceDisp8) {
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if (!ForceDisp32 && isDisp8(DispVal))
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emitConstant(DispVal, 1);
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else if (GV)
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emitGlobalAddressForPtr(GV, DispVal);
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else
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emitConstant(DispVal, 4);
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if (ForceDisp8) {
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emitConstant(DispVal, 1);
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} else if (DispVal != 0 || ForceDisp32) {
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emitDisplacementField(DispForReloc, DispVal);
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}
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}
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}
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@ -420,6 +433,7 @@ void Emitter::emitInstruction(const MachineInstr &MI) {
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if (MI.getNumOperands() == 2) {
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const MachineOperand &MO1 = MI.getOperand(1);
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if (Value *V = MO1.getVRegValueOrNull()) {
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assert(0 && "??");
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assert(sizeOfImm(Desc) == 4 &&
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"Don't know how to emit non-pointer values!");
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emitGlobalAddressForPtr(cast<GlobalValue>(V));
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