================
@@ -596,6 +600,90 @@ bool BPFMIPreEmitPeephole::adjustBranch() {
return Changed;
}
+static const unsigned CallerSavedRegs[] = {BPF::R0, BPF::R1, BPF::R2,
+ BPF::R3, BPF::R4, BPF::R5};
+
+struct BPFFastCall {
+ MachineInstr *MI;
+ unsigned LiveCallerSavedRegs;
+};
+
+static void collectBPFFastCalls(const TargetRegisterInfo *TRI,
+ LivePhysRegs &LiveRegs, MachineBasicBlock &BB,
+ SmallVectorImpl<BPFFastCall> &Calls) {
+ LiveRegs.init(*TRI);
+ LiveRegs.addLiveOuts(BB);
+ Calls.clear();
+ for (MachineInstr &MI : llvm::reverse(BB)) {
+ unsigned LiveCallerSavedRegs;
+ if (!MI.isCall())
+ goto NextInsn;
+ LiveCallerSavedRegs = 0;
+ for (MCRegister R : CallerSavedRegs) {
+ bool DoSpillFill = !MI.definesRegister(R, TRI) && LiveRegs.contains(R);
+ if (!DoSpillFill)
+ continue;
+ LiveCallerSavedRegs |= 1 << R;
+ }
+ if (LiveCallerSavedRegs)
+ Calls.push_back({&MI, LiveCallerSavedRegs});
+ NextInsn:
+ LiveRegs.stepBackward(MI);
+ }
+}
+
+static int64_t computeMinFixedObjOffset(MachineFrameInfo &MFI,
+ unsigned SlotSize) {
+ int64_t MinFixedObjOffset = 0;
+ // Same logic as in X86FrameLowering::adjustFrameForMsvcCxxEh()
+ for (int I = MFI.getObjectIndexBegin(); I < MFI.getObjectIndexEnd(); ++I) {
+ if (MFI.isDeadObjectIndex(I))
+ continue;
+ MinFixedObjOffset = std::min(MinFixedObjOffset, MFI.getObjectOffset(I));
+ }
+ MinFixedObjOffset -=
+ (SlotSize + MinFixedObjOffset % SlotSize) & (SlotSize - 1);
+ return MinFixedObjOffset;
+}
+
+bool BPFMIPreEmitPeephole::insertMissingCallerSavedSpills() {
+ MachineFrameInfo &MFI = MF->getFrameInfo();
+ SmallVector<BPFFastCall, 8> Calls;
+ LivePhysRegs LiveRegs;
+ const unsigned SlotSize = 8;
+ int64_t MinFixedObjOffset = computeMinFixedObjOffset(MFI, SlotSize);
+ bool Changed = false;
+ for (MachineBasicBlock &BB : *MF) {
+ collectBPFFastCalls(TRI, LiveRegs, BB, Calls);
+ Changed |= !Calls.empty();
----------------
yonghong-song wrote:
Calls.empty() does not mean changed unless there are actual fill/spill, right?
https://github.com/llvm/llvm-project/pull/101228
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