[clang] [llvm] [RISCV] Support frame pointers in SiFive CLIC preemptible handlers (PR #221318)

[Sam Elliott via cfe-commits]

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@@ -1456,15 +1433,12 @@ void RISCVFrameLowering::emitEpilogue(MachineFunction &MF,
   if (NeedsDwarfCFI && hasFP(MF))
     CFIBuilder.buildDefCFA(SPReg, RealStackSize);
 
-  // With a frame pointer, restore the SiFive CLIC CSRs through X5.
-  if (hasFP(MF))
-    emitSiFiveCLICPreemptibleRestores(MF, MBB, FirstScalarCSRRestoreInsn, DL);
-
   // Skip to after the restores of scalar callee-saved registers
   // FIXME: assumes exactly one instruction is used to restore each
   // callee-saved register.
   MBBI = std::next(FirstScalarCSRRestoreInsn,
-                   getUnmanagedCSI(MF, CSI, PreferAscendingLS).size());
+                   getScalarSpillCSI(MF, CSI, PreferAscendingLS).size());
+  emitSiFiveCLICPreemptibleRestores(MF, MBB, MBBI, DL);
   CFIBuilder.setInsertPoint(MBBI);
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lenary wrote:

I don't think I understand why we're moving MBBI but not the CFIBuilder's insert point. I sort of think of those two as atomically representing each other -- can we move the `setInsertPoint` one line earlier, and then pass the `CFIBuilder` into `emitSiFiveCLICPreemptibleRestores` so we don't have to create a new one?

https://github.com/llvm/llvm-project/pull/221318