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Look for downward jumps for elses when scanning.

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Otherwise, we often end the function earlier than it should be.
This commit is contained in:
Unknown W. Brackets 2013-12-01 21:28:09 -08:00
parent 43be44947f
commit 1bccfa4141
1 changed files with 63 additions and 5 deletions
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68
Core/MIPS/MIPSAnalyst.cpp
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@ -238,6 +238,57 @@ namespace MIPSAnalyst {
}
}
static u32 ScanAheadForJumpback(u32 fromAddr, u32 knownStart, u32 knownEnd) {
static const u32 MAX_AHEAD_SCAN = 0x1000;
// Code might jump halfway up to before fromAddr, but after knownEnd.
// In that area, there could be another jump up to the valid range.
// So we track that for a second scan.
u32 closestJumpbackAddr = INVALIDTARGET;
u32 closestJumpbackTarget = fromAddr;
// We assume the furthest jumpback is within the func.
u32 furthestJumpbackAddr = INVALIDTARGET;
for (u32 ahead = fromAddr; ahead < fromAddr + MAX_AHEAD_SCAN; ahead += 4) {
MIPSOpcode aheadOp = Memory::Read_Instruction(ahead);
u32 target = GetBranchTargetNoRA(ahead);
if (target == INVALIDTARGET && ((aheadOp & 0xFC000000) == 0x08000000)) {
target = GetJumpTarget(ahead);
}
if (target != INVALIDTARGET) {
// Only if it comes back up to known code within this func.
if (target >= knownStart && target <= knownEnd) {
furthestJumpbackAddr = ahead;
}
// But if it jumps above fromAddr, we should scan that area too...
if (target < closestJumpbackTarget && target < fromAddr && target > knownEnd) {
closestJumpbackAddr = ahead;
closestJumpbackTarget = target;
}
}
}
if (closestJumpbackAddr != INVALIDTARGET && furthestJumpbackAddr == INVALIDTARGET) {
for (u32 behind = closestJumpbackTarget; behind < fromAddr; behind += 4) {
MIPSOpcode behindOp = Memory::Read_Instruction(behind);
u32 target = GetBranchTargetNoRA(behind);
if (target == INVALIDTARGET && ((behindOp & 0xFC000000) == 0x08000000)) {
target = GetJumpTarget(behind);
}
if (target != INVALIDTARGET) {
if (target >= knownStart && target <= knownEnd) {
furthestJumpbackAddr = closestJumpbackAddr;
}
}
}
}
return furthestJumpbackAddr;
}
void ScanForFunctions(u32 startAddr, u32 endAddr /*, std::vector<u32> knownEntries*/) {
Function currentFunction = {startAddr};
@ -283,14 +334,21 @@ namespace MIPSAnalyst {
if (looking) {
if (addr >= furthestBranch) {
u32 sureTarget = GetSureBranchTarget(addr);
// Regular j only, jals are to new funcs.
if (sureTarget == INVALIDTARGET && ((op & 0xFC000000) == 0x08000000)) {
sureTarget = GetJumpTarget(addr);
}
if (sureTarget != INVALIDTARGET && sureTarget < addr) {
end = true;
} else if (sureTarget != INVALIDTARGET) {
// Okay, we have a downward jump. Might be an else or a tail call...
// If there's a jump back upward in spitting distance of it, it's an else.
u32 jumpback = ScanAheadForJumpback(sureTarget, currentFunction.start, furthestBranch);
if (jumpback != INVALIDTARGET && jumpback > addr && jumpback > furthestBranch) {
furthestBranch = jumpback;
}
}
sureTarget = GetJumpTarget(addr);
if (sureTarget != INVALIDTARGET && sureTarget < addr && ((op&0xFC000000)==0x08000000)) {
end = true;
}
//end = true;
}
}
if (end) {