[llvm] Spill/restore FP/BP around instructions in which they are clobbered (PR #81048)

[via llvm-commits]

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@@ -4178,3 +4178,158 @@ void X86FrameLowering::restoreWinEHStackPointersInParent(
                                   /*RestoreSP=*/IsSEH);
   }
 }
+
+static int computeSPAdjust4SpillFPBP(MachineFunction &MF,
+                                     const TargetRegisterClass *RC,
+                                     unsigned SpillRegNum) {
+  const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
+  unsigned AllocSize = TRI->getSpillSize(*RC) * SpillRegNum;
+  Align StackAlign = MF.getFrameInfo().getStackAlignment();
+  unsigned AlignedSize = alignTo(AllocSize, StackAlign);
+  return AlignedSize - AllocSize;
+}
+
+void X86FrameLowering::spillFPBPUsingSP(MachineFunction &MF,
+                                        MachineBasicBlock::iterator BeforeMI,
+                                        bool SpillFP, bool SpillBP) const {
+  const TargetRegisterClass *RC;
+  unsigned RegNum = 0;
+  MachineBasicBlock *MBB = BeforeMI->getParent();
+  DebugLoc DL = BeforeMI->getDebugLoc();
+
+  // Spill FP.
+  if (SpillFP) {
+    Register FP = TRI->getFrameRegister(MF);
+    if (STI.isTarget64BitILP32())
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zmodem wrote:

Should we have a test case covering X32?

https://github.com/llvm/llvm-project/pull/81048