[PATCH] D62597: [mips] Extend range of register indexes accepted by cfcmsa/ctcmsa

[Simon Atanasyan via Phabricator via llvm-commits]

atanasyan created this revision.
atanasyan added a reviewer: Petar.Avramovic.
Herald added subscribers: arphaman, jrtc27, hiraditya, arichardson, sdardis.
Herald added a project: LLVM.

The `cfcmsa` and `ctcmsa` instructions accept index of MSA control register. The MIPS64 SIMD Architecture define eight MSA control registers. But register index for `cfcmsa` and `ctcmsa` instructions might be any number in 0..31 range. If the index is greater then 7, `cfcmsa` writes zero to the destination registers and `ctcmsa` does nothing [1].

[1] MIPS Architecture for Programmers Volume IV-j: The MIPS64 SIMD Architecture Module
https://www.mips.com/?do-download=the-mips64-simd-architecture-module


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D62597

Files:
  llvm/lib/Target/Mips/MipsRegisterInfo.td
  llvm/lib/Target/Mips/MipsSEISelDAGToDAG.cpp
  llvm/test/CodeGen/Mips/msa/elm_cxcmsa.ll


Index: llvm/test/CodeGen/Mips/msa/elm_cxcmsa.ll
===================================================================
--- llvm/test/CodeGen/Mips/msa/elm_cxcmsa.ll
+++ llvm/test/CodeGen/Mips/msa/elm_cxcmsa.ll
@@ -84,6 +84,15 @@
 ; CHECK: cfcmsa $[[R1:[0-9]+]], $7
 ; CHECK: .size msa_unmap_cfcmsa_test
 ;
+define i32 @msa_invalid_reg_cfcmsa_test() nounwind {
+entry:
+  %0 = tail call i32 @llvm.mips.cfcmsa(i32 8)
+  ret i32 %0
+}
+
+; CHECK-LABEL: msa_invalid_reg_cfcmsa_test:
+; CHECK: cfcmsa ${{[0-9]+}}, $8
+;
 define void @msa_ir_ctcmsa_test() nounwind {
 entry:
   tail call void @llvm.mips.ctcmsa(i32 0, i32 1)
@@ -164,5 +173,14 @@
 ; CHECK: ctcmsa $7
 ; CHECK: .size msa_unmap_ctcmsa_test
 ;
+define void @msa_invalid_reg_ctcmsa_test() nounwind {
+entry:
+  tail call void @llvm.mips.ctcmsa(i32 8, i32 1)
+  ret void
+}
+
+; CHECK: msa_invalid_reg_ctcmsa_test:
+; CHECK: ctcmsa $8
+;
 declare i32 @llvm.mips.cfcmsa(i32) nounwind
 declare void @llvm.mips.ctcmsa(i32, i32) nounwind
Index: llvm/lib/Target/Mips/MipsSEISelDAGToDAG.cpp
===================================================================
--- llvm/lib/Target/Mips/MipsSEISelDAGToDAG.cpp
+++ llvm/lib/Target/Mips/MipsSEISelDAGToDAG.cpp
@@ -75,18 +75,8 @@
 }
 
 unsigned MipsSEDAGToDAGISel::getMSACtrlReg(const SDValue RegIdx) const {
-  switch (cast<ConstantSDNode>(RegIdx)->getZExtValue()) {
-  default:
-    llvm_unreachable("Could not map int to register");
-  case 0: return Mips::MSAIR;
-  case 1: return Mips::MSACSR;
-  case 2: return Mips::MSAAccess;
-  case 3: return Mips::MSASave;
-  case 4: return Mips::MSAModify;
-  case 5: return Mips::MSARequest;
-  case 6: return Mips::MSAMap;
-  case 7: return Mips::MSAUnmap;
-  }
+  uint64_t RegNum = cast<ConstantSDNode>(RegIdx)->getZExtValue();
+  return Mips::MSACtrlRegClass.getRegister(RegNum);
 }
 
 bool MipsSEDAGToDAGISel::replaceUsesWithZeroReg(MachineRegisterInfo *MRI,
Index: llvm/lib/Target/Mips/MipsRegisterInfo.td
===================================================================
--- llvm/lib/Target/Mips/MipsRegisterInfo.td
+++ llvm/lib/Target/Mips/MipsRegisterInfo.td
@@ -258,6 +258,11 @@
   def MSARequest : MipsReg<5, "5">;
   def MSAMap     : MipsReg<6, "6">;
   def MSAUnmap   : MipsReg<7, "7">;
+  // MSA-ASE fake control registers.
+  // These registers do not exist, but instructions like `cfcmsa`
+  // and `ctcmsa` allows to specify them.
+  foreach I = 8-31 in
+  def MSA#I : MipsReg<#I, ""#I>;
 
   // Octeon multiplier and product registers
   def MPL0 : MipsReg<0, "mpl0">;
@@ -438,7 +443,8 @@
                                 (decimate (sequence "W%u", 0, 31), 2)>;
 
 def MSACtrl: RegisterClass<"Mips", [i32], 32, (add
-  MSAIR, MSACSR, MSAAccess, MSASave, MSAModify, MSARequest, MSAMap, MSAUnmap)>;
+  MSAIR, MSACSR, MSAAccess, MSASave, MSAModify, MSARequest, MSAMap, MSAUnmap,
+  (sequence "MSA%u", 8, 31))>, Unallocatable;
 
 // Hi/Lo Registers
 def LO32 : RegisterClass<"Mips", [i32], 32, (add LO0)>;


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