[llvm] [RISCV][WIP] Let RA do the CSR saves. (PR #90819)

[Michael Maitland via llvm-commits]

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@@ -1164,6 +1170,7 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &MF) {
 void PEI::insertPrologEpilogCode(MachineFunction &MF) {
   const TargetFrameLowering &TFI = *MF.getSubtarget().getFrameLowering();
 
+  TFI.emitCFIsForCSRsHandledByRA(MF, RDA);
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michaelmaitland wrote:

It might be nice to add a comment explaining that CSRs that are handled by RA still need CFI information and emitPrologue does not emit CFI info for those, since the CSRs may no longer be located in the prologue.

https://github.com/llvm/llvm-project/pull/90819