[llvm] 6082a50 - [RISCV] Mark all registers marked isConstant as reserved (#96002)

[via llvm-commits]

Author: Francis Visoiu Mistrih
Date: 2024-06-23T15:44:41-07:00
New Revision: 6082a50a9835907f5f90f1967e21dcd7f5ab30f1

URL: https://github.com/llvm/llvm-project/commit/6082a50a9835907f5f90f1967e21dcd7f5ab30f1
DIFF: https://github.com/llvm/llvm-project/commit/6082a50a9835907f5f90f1967e21dcd7f5ab30f1.diff

LOG: [RISCV] Mark all registers marked isConstant as reserved (#96002)

This makes use of the information from TableGen instead of duplicating
it in the code.

Added: 
    

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

Removed: 
    


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diff  --git a/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp b/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
index caa5dbc15f8bd..760d12103c36d 100644
--- a/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
@@ -104,14 +104,17 @@ BitVector RISCVRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
   BitVector Reserved(getNumRegs());
   auto &Subtarget = MF.getSubtarget<RISCVSubtarget>();
 
-  // Mark any registers requested to be reserved as such
   for (size_t Reg = 0; Reg < getNumRegs(); Reg++) {
+    // Mark any GPRs requested to be reserved as such
     if (Subtarget.isRegisterReservedByUser(Reg))
       markSuperRegs(Reserved, Reg);
+
+    // Mark all the registers defined as constant in TableGen as reserved.
+    if (isConstantPhysReg(Reg))
+      markSuperRegs(Reserved, Reg);
   }
 
   // Use markSuperRegs to ensure any register aliases are also reserved
-  markSuperRegs(Reserved, RISCV::X0); // zero
   markSuperRegs(Reserved, RISCV::X2); // sp
   markSuperRegs(Reserved, RISCV::X3); // gp
   markSuperRegs(Reserved, RISCV::X4); // tp
@@ -136,7 +139,6 @@ BitVector RISCVRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
   markSuperRegs(Reserved, RISCV::VTYPE);
   markSuperRegs(Reserved, RISCV::VXSAT);
   markSuperRegs(Reserved, RISCV::VXRM);
-  markSuperRegs(Reserved, RISCV::VLENB); // vlenb (constant)
 
   // Floating point environment registers.
   markSuperRegs(Reserved, RISCV::FRM);