private void compileDelaySlot(
CompilerContext context, MethodVisitor mv, CodeInstruction delaySlotCodeInstruction) {
if (delaySlotCodeInstruction == null) {
log.error(String.format("Cannot find delay slot instruction at 0x%08X", getAddress() + 4));
return;
}
if (delaySlotCodeInstruction.hasFlags(Instruction.FLAG_HAS_DELAY_SLOT)) {
// Issue a warning when compiling an instruction having a delay slot inside a delay slot.
// See http://code.google.com/p/pcsx2/source/detail?r=5541
String lineSeparator = System.getProperty("line.separator");
log.warn(
String.format(
"Instruction in a delay slot having a delay slot:%s%s%s%s",
lineSeparator, this, lineSeparator, delaySlotCodeInstruction));
}
delaySlotCodeInstruction.setIsDelaySlot(true);
Label delaySlotLabel = null;
if (delaySlotCodeInstruction.hasLabel()) {
delaySlotLabel = delaySlotCodeInstruction.getLabel();
delaySlotCodeInstruction.forceNewLabel();
}
delaySlotCodeInstruction.compile(context, mv);
if (delaySlotLabel != null) {
delaySlotCodeInstruction.setLabel(delaySlotLabel);
} else if (delaySlotCodeInstruction.hasLabel()) {
delaySlotCodeInstruction.forceNewLabel();
}
context.setCodeInstruction(this);
context.skipInstructions(1, false);
}
private int getBranchingOpcodeBranch2(
CompilerContext context, MethodVisitor mv, int branchingOpcode, int notBranchingOpcode) {
// Retrieve the registers for the branching opcode before executing
// the delay slot instruction, as it might theoretically modify the
// content of these registers.
branchingOpcode = loadRegistersForBranchingOpcodeBranch2(context, mv, branchingOpcode);
CodeInstruction delaySlotCodeInstruction = getDelaySlotCodeInstruction(context);
if (delaySlotCodeInstruction != null
&& delaySlotCodeInstruction.hasFlags(Instruction.FLAG_HAS_DELAY_SLOT)) {
// We are compiling a sequence where the delay instruction has itself a delay slot:
// beq $reg1, $reg2, label
// jr $ra
// nop
// Handle the sequence by inserting one nop between the instructions:
// bne $reg1, $reg2, label
// nop
// jr $ra
// nop
String lineSeparator = System.getProperty("line.separator");
log.warn(
String.format(
"Instruction in a delay slot having a delay slot:%s%s%s%s",
lineSeparator, this, lineSeparator, delaySlotCodeInstruction));
} else {
compileDelaySlot(context, mv, delaySlotCodeInstruction);
}
if (branchingOpcode == Opcodes.GOTO && getBranchingTo() == getAddress()) {
context.visitLogInfo(
mv,
String.format("Pausing emulator - branch to self (death loop) at 0x%08X", getAddress()));
context.visitPauseEmuWithStatus(mv, Emulator.EMU_STATUS_JUMPSELF);
}
return branchingOpcode;
}
private void compileBranch(CompilerContext context, MethodVisitor mv) {
int branchingOpcode = getBranchingOpcode(context, mv);
if (branchingOpcode != Opcodes.NOP) {
CodeInstruction branchingToCodeInstruction =
context.getCodeBlock().getCodeInstruction(getBranchingTo());
// Fallback when branching to the 2nd instruction of a native code sequence whose
// 1st instruction is the delay slot instruction.
// In such a case, assume a branch to the native code sequence.
if (branchingToCodeInstruction == null) {
CodeInstruction nativeCodeInstruction = context.getCodeInstruction(getBranchingTo() - 4);
if (nativeCodeInstruction != null
&& nativeCodeInstruction instanceof NativeCodeInstruction) {
NativeCodeSequence nativeCodeSequence =
((NativeCodeInstruction) nativeCodeInstruction).getNativeCodeSequence();
if (getDelaySlotCodeInstruction(context).getOpcode()
== nativeCodeSequence.getFirstOpcode()) {
if (log.isDebugEnabled()) {
log.debug(
String.format(
"0x%08X: branching to the 2nd instruction of a native code sequence, assuming the 1st instruction",
getAddress()));
}
branchingToCodeInstruction = nativeCodeInstruction;
}
}
}
if (branchingToCodeInstruction != null) {
// Some applications do have branches to delay slot instructions
// (probably from programmers that didn't know/care about delay slots).
//
// Handle a branch to a NOP in a delay slot: just skip the NOP and assume the branch
// is to the instruction following the NOP.
// E.g.:
// 0x00000000 b 0x00000014 -> branching to a NOP in a delay slot, assume a branch to
// 0x00000018
// 0x00000004 nop
// ...
// 0x00000010 b 0x00000020
// 0x00000014 nop
// 0x00000018 something
//
if (branchingToCodeInstruction.getInsn() == Instructions.NOP) {
CodeInstruction beforeBranchingToCodeInstruction =
context.getCodeBlock().getCodeInstruction(getBranchingTo() - 4);
if (beforeBranchingToCodeInstruction != null
&& beforeBranchingToCodeInstruction.hasFlags(Instruction.FLAG_HAS_DELAY_SLOT)) {
if (log.isDebugEnabled()) {
log.debug(
String.format(
"0x%08X: branching to a NOP in a delay slot, correcting to the next instruction",
getAddress()));
}
branchingToCodeInstruction =
context.getCodeBlock().getCodeInstruction(getBranchingTo() + 4);
}
}
context.visitJump(branchingOpcode, branchingToCodeInstruction);
} else {
context.visitJump(branchingOpcode, getBranchingTo());
}
}
}