[llvm] [RISCV][MC] Name the vector tuple registers (PR #102726)

[Brandon Wu via llvm-commits]

https://github.com/4vtomat created https://github.com/llvm/llvm-project/pull/102726

Currently vector tuple registers don't have the specified names, the
default name is, for example: `VRN3M2` -> `V8M2_V10M2_V12M2`, however
it's equivalent to `v8` in the assembly.


>From 87c226a66a8a25b19f6414c53ad1fe18ceb926dc Mon Sep 17 00:00:00 2001
From: Brandon Wu <brandon.wu at sifive.com>
Date: Fri, 9 Aug 2024 22:51:46 -0700
Subject: [PATCH] [RISCV][MC] Name the vector tuple registers

Currently vector tuple registers don't have the specified names, the
default name is, for example: `VRN3M2` -> `V8M2_V10M2_V12M2`, however
it's equivalent to `v8` in the assembly.
---
 llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp  | 13 -------------
 llvm/lib/Target/RISCV/RISCVRegisterInfo.td | 17 +++++++++++++----
 2 files changed, 13 insertions(+), 17 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp b/llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp
index 93677433c04405..cca2676de61dd1 100644
--- a/llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp
+++ b/llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp
@@ -1008,19 +1008,6 @@ static bool lowerRISCVVMachineInstrToMCInst(const MachineInstr *MI,
       } else if (RISCV::FPR64RegClass.contains(Reg)) {
         Reg = TRI->getSubReg(Reg, RISCV::sub_32);
         assert(Reg && "Superregister does not exist");
-      } else if (RISCV::VRN2M1RegClass.contains(Reg) ||
-                 RISCV::VRN2M2RegClass.contains(Reg) ||
-                 RISCV::VRN2M4RegClass.contains(Reg) ||
-                 RISCV::VRN3M1RegClass.contains(Reg) ||
-                 RISCV::VRN3M2RegClass.contains(Reg) ||
-                 RISCV::VRN4M1RegClass.contains(Reg) ||
-                 RISCV::VRN4M2RegClass.contains(Reg) ||
-                 RISCV::VRN5M1RegClass.contains(Reg) ||
-                 RISCV::VRN6M1RegClass.contains(Reg) ||
-                 RISCV::VRN7M1RegClass.contains(Reg) ||
-                 RISCV::VRN8M1RegClass.contains(Reg)) {
-        Reg = TRI->getSubReg(Reg, RISCV::sub_vrm1_0);
-        assert(Reg && "Subregister does not exist");
       }
 
       MCOp = MCOperand::createReg(Reg);
diff --git a/llvm/lib/Target/RISCV/RISCVRegisterInfo.td b/llvm/lib/Target/RISCV/RISCVRegisterInfo.td
index b12634c24622f4..efdf6bebfce301 100644
--- a/llvm/lib/Target/RISCV/RISCVRegisterInfo.td
+++ b/llvm/lib/Target/RISCV/RISCVRegisterInfo.td
@@ -423,10 +423,12 @@ class IndexSet<int tuple_index, int nf, int lmul, bit isV0 = false> {
 
 // This class returns a list of vector register collections.
 // For example, for NF = 2 and LMUL = 4,
-// it will return
+// L would be:
 //   ([ V8M4, V12M4, V16M4, V20M4, V24M4, V4M4],
 //    [V12M4, V16M4, V20M4, V24M4, V28M4, V8M4])
-//
+// Names are the starting register of each register list,
+// in this example:
+//   ["v8", "v12", "v16", "v20", "v24", "v4"]
 class VRegList<list<dag> LIn, int start, int nf, int lmul, bit isV0> {
   list<dag> L =
     !if(!ge(start, nf),
@@ -440,6 +442,9 @@ class VRegList<list<dag> LIn, int start, int nf, int lmul, bit isV0> {
                 !listsplat("",
                   !size(IndexSet<start, nf, lmul, isV0>.R)))],
           VRegList<LIn, !add(start, 1), nf, lmul, isV0>.L));
+  list<string> Names =
+    !if(!ge(start, nf), [],
+        !foreach(i, IndexSet<start, nf, lmul, isV0>.R, "v" # i));
 }
 
 // Vector registers
@@ -491,12 +496,16 @@ def VCSR : RISCVRegisterClass<[XLenVT], 32,
 
 foreach m = [1, 2, 4] in {
   foreach n = NFList<m>.L in {
+    defvar RegListWOV0 = VRegList<[], 0, n, m, false>;
+    defvar RegListWV0 = VRegList<[], 0, n, m, true>;
     def "VN" # n # "M" # m # "NoV0": RegisterTuples<
                                        SubRegSet<n, m>.L,
-                                       VRegList<[], 0, n, m, false>.L>;
+                                       RegListWOV0.L,
+                                       RegListWOV0.Names>;
     def "VN" # n # "M" # m # "V0" : RegisterTuples<
                                        SubRegSet<n, m>.L,
-                                       VRegList<[], 0, n, m, true>.L>;
+                                       RegListWV0.L,
+                                       RegListWV0.Names>;
   }
 }