[llvm] [clang] [RISCV] CodeGen of RVE and ilp32e/lp64e ABIs (PR #76777)

[Wang Pengcheng via cfe-commits]

================
@@ -985,9 +1003,10 @@ void RISCVFrameLowering::determineCalleeSaves(MachineFunction &MF,
     };
 
     for (auto Reg : CSRegs)
-      SavedRegs.set(Reg);
+      if (Reg < RISCV::X16 || !Subtarget.isRVE())
----------------
wangpc-pp wrote:

The psABI says:
> If used with an ISA that has any of the registers x16-x31 and f0-f31, then these registers are considered temporaries.

So I think we should.

https://github.com/llvm/llvm-project/pull/76777