[llvm] ce1270f - [RISCV] Remove shadow register list passed to AllocateReg when allocating FP registers for calling convention

[Craig Topper via llvm-commits]

Author: Craig Topper
Date: 2020-11-05T09:49:42-08:00
New Revision: ce1270fc7e3d71f5769d4f9d151b275c6733c89d

URL: https://github.com/llvm/llvm-project/commit/ce1270fc7e3d71f5769d4f9d151b275c6733c89d
DIFF: https://github.com/llvm/llvm-project/commit/ce1270fc7e3d71f5769d4f9d151b275c6733c89d.diff

LOG: [RISCV] Remove shadow register list passed to AllocateReg when allocating FP registers for calling convention

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

Added: 
    

Modified: 
    llvm/lib/Target/RISCV/RISCVISelLowering.cpp

Removed: 
    


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diff  --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 17b3a168b9cb..72ecf55e672b 100644
--- 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 =