[RISCV] Remove shadow register list passed to AllocateReg when allocating FP register...

The _F and _D registers are already sub/super registers. When one gets allocated all its aliases are already marked as allocated. We don't need to explicitly shadow it too.

I believe shadow is for calling conventions like 64-bit Windows on X86 where have rules like this

CCIfType<[i32], CCAssignToRegWithShadow<[ECX , EDX , R8D , R9D ],
                                         [XMM0, XMM1, XMM2, XMM3]>>

For that calling convention the argument number determines which register is used regardless of how many scalars or vectors came before it.

Removing this removes a question I had in D90738.

Differential Revision: https://reviews.llvm.org/D90801

diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 17b3a16..72ecf55 100644 (file)
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -1669,9 +1669,9 @@ static bool CC_RISCV(const DataLayout &DL, RISCVABI::ABI ABI, unsigned ValNo,
   // Allocate to a register if possible, or else a stack slot.
   Register Reg;
   if (ValVT == MVT::f32 && !UseGPRForF32)
-    Reg = State.AllocateReg(ArgFPR32s, ArgFPR64s);
+    Reg = State.AllocateReg(ArgFPR32s);
   else if (ValVT == MVT::f64 && !UseGPRForF64)
-    Reg = State.AllocateReg(ArgFPR64s, ArgFPR32s);
+    Reg = State.AllocateReg(ArgFPR64s);
   else
     Reg = State.AllocateReg(ArgGPRs);
   unsigned StackOffset =