[mips][mips64r6] ssnop is deprecated on MIPS32r6/MIPS64r6

[dsanders]

Summary

Depends on D4120

[zoran.jovanovic]

LGTM

[vmedic]

LGTM

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

#include "MipsGenAsmMatcher.inc"
   bool isN64() const { return STI.getFeatureBits() & Mips::FeatureN64; }
 
   bool isMicroMips() const {
     return STI.getFeatureBits() & Mips::FeatureMicroMips;
   }
 
   bool hasMips4() const { return STI.getFeatureBits() & Mips::FeatureMips4; }
   bool hasMips32() const { return STI.getFeatureBits() & Mips::FeatureMips32; }
+  bool hasMips32r6() const {
+    return STI.getFeatureBits() & Mips::FeatureMips32r6;
+  }
+  bool hasMips64r6() const {
+    return STI.getFeatureBits() & Mips::FeatureMips64r6;
+  }
 
   bool parseRegister(unsigned &RegNum);
 
   bool eatComma(StringRef ErrorStr);
 
   int matchCPURegisterName(StringRef Symbol);
 
   int matchRegisterByNumber(unsigned RegNum, unsigned RegClass);
case Mips::BC1T_MM:
       if (!isIntN(isMicroMips() ? 17 : 18, Offset.getImm()))
         return Error(IDLoc, "branch target out of range");
       if (OffsetToAlignment(Offset.getImm(), 1LL << (isMicroMips() ? 1 : 2)))
         return Error(IDLoc, "branch to misaligned address");
       break;
     }
   }
 
+  // SSNOP is deprecated on MIPS32r6/MIPS64r6
+  // We still accept it but it is a normal nop.
+  if (hasMips32r6() && Inst.getOpcode() == Mips::SSNOP) {
+    std::string ISA = hasMips64r6() ? "MIPS64r6" : "MIPS32r6";
+    Warning(IDLoc, "ssnop is deprecated for " + ISA + " and is equivalent to a "
+                                                      "nop instruction");
+  }
+
   if (MCID.hasDelaySlot() && Options.isReorder()) {
     // If this instruction has a delay slot and .set reorder is active,
     // emit a NOP after it.
     Instructions.push_back(Inst);
     MCInst NopInst;
     NopInst.setOpcode(Mips::SLL);
     NopInst.addOperand(MCOperand::CreateReg(Mips::ZERO));
     NopInst.addOperand(MCOperand::CreateReg(Mips::ZERO));

lib/Target/Mips/Mips32r6InstrInfo.td

 //=- Mips32r6InstrInfo.td - Mips32r6 Instruction Information -*- tablegen -*-=//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file describes Mips32r6 instructions.
 //
 //===----------------------------------------------------------------------===//
 
 include "Mips32r6InstrFormats.td"
 
 // Notes about removals/changes from MIPS32r6:
-// Unclear: ssnop
 // Reencoded: jr -> jalr
 // Reencoded: jr.hb -> jalr.hb
 // Reencoded: sdbbp
 
 def brtarget21 : Operand<OtherVT> {
   let EncoderMethod = "getBranchTarget21OpValue";
   let OperandType = "OPERAND_PCREL";
   let DecoderMethod = "DecodeBranchTarget21";

test/MC/Mips/mips32r6/valid.s

 # Instructions that are valid
 #
 # Branches have some unusual encoding rules in MIPS32r6 so we need to test:
 #   rs == 0
 #   rs != 0
 #   rt == 0
 #   rt != 0
 #   rs < rt
 #   rs == rt
 #   rs > rt
 # appropriately for each branch instruction
 #
-# RUN: llvm-mc %s -triple=mips-unknown-linux -show-encoding -mcpu=mips32r6 | FileCheck %s
+# RUN: llvm-mc %s -triple=mips-unknown-linux -show-encoding -mcpu=mips32r6 2> %t0 | FileCheck %s
+# RUN: FileCheck %s -check-prefix=WARNING < %t0
 
         .set noat
         # FIXME: Add the instructions carried forward from older ISA's
         addiupc $4, 100          # CHECK: addiupc $4, 100     # encoding: [0xec,0x80,0x00,0x19]
         align   $4, $2, $3, 2    # CHECK: align $4, $2, $3, 2 # encoding: [0x7c,0x43,0x22,0xa0]
         aluipc  $3, 56           # CHECK: aluipc $3, 56       # encoding: [0xec,0x7f,0x00,0x38]
         aui     $3,$2,-23        # CHECK: aui $3, $2, -23     # encoding: [0x3c,0x62,0xff,0xe9]
         auipc   $3, -1           # CHECK: auipc $3, -1        # encoding: [0xec,0x7e,0xff,0xff]
# RUN: FileCheck %s -check-prefix=WARNING < %t0
         ldc2    $8, -701($at)    # CHECK: ldc2 $8, -701($1)      # encoding: [0x49,0xc8,0x0d,0x43]
         lwc2    $18,-841($a2)    # CHECK: lwc2 $18, -841($6)     # encoding: [0x49,0x52,0x34,0xb7]
         sdc2    $20,629($s2)     # CHECK: sdc2 $20, 629($18)     # encoding: [0x49,0xf4,0x92,0x75]
         swc2    $25,304($s0)     # CHECK: swc2 $25, 304($16)     # encoding: [0x49,0x79,0x81,0x30]
         ll      $v0,-153($s2)    # CHECK: ll $2, -153($18)       # encoding: [0x7e,0x42,0xb3,0xb6]
         sc      $15,-40($s3)     # CHECK: sc $15, -40($19)       # encoding: [0x7e,0x6f,0xec,0x26]
         clo     $11,$a1          # CHECK: clo $11, $5            # encoding: [0x00,0xa0,0x58,0x51]
         clz     $sp,$gp          # CHECK: clz $sp, $gp           # encoding: [0x03,0x80,0xe8,0x50]
+        ssnop                    # WARNING: [[@LINE]]:9: warning: ssnop is deprecated for MIPS32r6 and is equivalent to a nop instruction
+        ssnop                    # CHECK: ssnop                  # encoding: [0x00,0x00,0x00,0x40]

test/MC/Mips/mips64r6/valid.s

 # Instructions that are valid
 #
 # Branches have some unusual encoding rules in MIPS32r6 so we need to test:
 #   rs == 0
 #   rs != 0
 #   rt == 0
 #   rt != 0
 #   rs < rt
 #   rs == rt
 #   rs > rt
 # appropriately for each branch instruction
 #
-# RUN: llvm-mc %s -triple=mips-unknown-linux -show-encoding -mcpu=mips64r6 | FileCheck %s
+# RUN: llvm-mc %s -triple=mips-unknown-linux -show-encoding -mcpu=mips64r6 2> %t0 | FileCheck %s
+# RUN: FileCheck %s -check-prefix=WARNING < %t0
 
         .set noat
         # FIXME: Add the instructions carried forward from older ISA's
         addiupc $4, 100          # CHECK: addiupc $4, 100     # encoding: [0xec,0x80,0x00,0x19]
         align   $4, $2, $3, 2    # CHECK: align $4, $2, $3, 2 # encoding: [0x7c,0x43,0x22,0xa0]
         aluipc  $3, 56           # CHECK: aluipc $3, 56       # encoding: [0xec,0x7f,0x00,0x38]
         aui     $3,$2,-23        # CHECK: aui $3, $2, -23     # encoding: [0x3c,0x62,0xff,0xe9]
         auipc   $3, -1           # CHECK: auipc $3, -1        # encoding: [0xec,0x7e,0xff,0xff]
# RUN: FileCheck %s -check-prefix=WARNING < %t0
         ll      $v0,-153($s2)    # CHECK: ll $2, -153($18)       # encoding: [0x7e,0x42,0xb3,0xb6]
         lld     $zero,112($ra)   # CHECK: lld $zero, 112($ra)    # encoding: [0x7f,0xe0,0x38,0x37]
         sc      $15,-40($s3)     # CHECK: sc $15, -40($19)       # encoding: [0x7e,0x6f,0xec,0x26]
         scd     $15,-51($sp)     # CHECK: scd $15, -51($sp)      # encoding: [0x7f,0xaf,0xe6,0xa7]
         clo     $11,$a1          # CHECK: clo $11, $5            # encoding: [0x00,0xa0,0x58,0x51]
         clz     $sp,$gp          # CHECK: clz $sp, $gp           # encoding: [0x03,0x80,0xe8,0x50]
         dclo    $s2,$a2          # CHECK: dclo $18, $6           # encoding: [0x00,0xc0,0x90,0x53]
         dclz    $s0,$25          # CHECK: dclz $16, $25          # encoding: [0x03,0x20,0x80,0x52]
+        ssnop                    # WARNING: [[@LINE]]:9: warning: ssnop is deprecated for MIPS64r6 and is equivalent to a nop instruction
+        ssnop                    # CHECK: ssnop                  # encoding: [0x00,0x00,0x00,0x40]