[mips][microMIPS] Implement JALX instruction

[jkolek]

Summary

Implement 16-bit microMIPS jump and link exchange instruction - JALX.

[dsanders]

lib/Target/Mips/MipsInstrInfo.td

1213–1215 ↗

(On Diff #12897)

Could we fix this fixme comment? An either/or feature bit (e.g. FeatureMips3_32) would do the trick.

[jkolek]

lib/Target/Mips/MipsInstrInfo.td

1213–1215 ↗

(On Diff #12897)

We have tried to assemble JALX with GAS and it does generate valid mips32 JALX opcode without -mmicromips or -mips16 command line options. To have same behaviour as GCC current implementation is sufficient, and comment can be removed.

[jkolek]

This is first version of the patch with removed FIXME comment which says that JALX requires either MIPS16 or microMIPS in addition to MIPS32.
We have tried to assemble JALX with GAS and it does generate JALX opcode without -mmicromips or -mips16 command line options. To have same behaviour as GCC current implementation is sufficient, and comment can be removed.

[dsanders]

lib/Target/Mips/MipsInstrInfo.td

1213–1215 ↗

(On Diff #12897)

That makes sense to me. Thanks

[sstankovic]

LGTM

llvm/trunk/lib/Target/Mips/MicroMipsInstrInfo.td

let DecoderNamespace = "MicroMips", Predicates = [InMicroMips] in {
   def INS_MM : MMRel, InsBase<"ins", GPR32Opnd, uimm5, MipsIns>,
                EXT_FM_MM<0x0c>;
 
   /// Jump Instructions
   let DecoderMethod = "DecodeJumpTargetMM" in {
     def J_MM        : MMRel, JumpFJ<jmptarget_mm, "j", br, bb, "j">,
                       J_FM_MM<0x35>;
     def JAL_MM      : MMRel, JumpLink<"jal", calltarget_mm>, J_FM_MM<0x3d>;
+    def JALX_MM     : MMRel, JumpLink<"jalx", calltarget>, J_FM_MM<0x3c>;
   }
   def JR_MM   : MMRel, IndirectBranch<"jr", GPR32Opnd>, JR_FM_MM<0x3c>;
   def JALR_MM : JumpLinkReg<"jalr", GPR32Opnd>, JALR_FM_MM<0x03c>;
 
   /// Jump Instructions - Short Delay Slot
   def JALS_MM   : JumpLinkMM<"jals", calltarget_mm>, J_FM_MM<0x1d>;
   def JALRS_MM  : JumpLinkRegMM<"jalrs", GPR32Opnd>, JALR_FM_MM<0x13c>;
 

llvm/trunk/lib/Target/Mips/MipsInstrInfo.td

 def B       : UncondBranch<BEQ>;
 
 def JAL  : MMRel, JumpLink<"jal", calltarget>, FJ<3>;
 let AdditionalPredicates = [NotInMicroMips] in {
   def JALR : JumpLinkReg<"jalr", GPR32Opnd>, JALR_FM;
   def JALRPseudo : JumpLinkRegPseudo<GPR32Opnd, JALR, RA>;
 }
 
-// FIXME: JALX really requires either MIPS16 or microMIPS in addition to MIPS32.
-def JALX  : JumpLink<"jalx", calltarget>, FJ<0x1D>, ISA_MIPS32_NOT_32R6_64R6;
+def JALX : MMRel, JumpLink<"jalx", calltarget>, FJ<0x1D>,
+           ISA_MIPS32_NOT_32R6_64R6;
 def BGEZAL : MMRel, BGEZAL_FT<"bgezal", brtarget, GPR32Opnd>, BGEZAL_FM<0x11>,
              ISA_MIPS1_NOT_32R6_64R6;
 def BGEZALL : MMRel, BGEZAL_FT<"bgezall", brtarget, GPR32Opnd, 0>,
               BGEZAL_FM<0x13>, ISA_MIPS2_NOT_32R6_64R6;
 def BLTZAL : MMRel, BGEZAL_FT<"bltzal", brtarget, GPR32Opnd>, BGEZAL_FM<0x10>,
              ISA_MIPS1_NOT_32R6_64R6;
 def BLTZALL : MMRel, BGEZAL_FT<"bltzall", brtarget, GPR32Opnd, 0>,
               BGEZAL_FM<0x12>, ISA_MIPS2_NOT_32R6_64R6;

llvm/trunk/test/MC/Mips/micromips-jump-instructions.s

 # CHECK-EL: jal 1328    # encoding: [0x00,0xf4,0x98,0x02]
 # CHECK-EL: nop         # encoding: [0x00,0x00,0x00,0x00]
 # CHECK-EL: jalr $ra, $6 # encoding: [0xe6,0x03,0x3c,0x0f]
 # CHECK-EL: nop         # encoding: [0x00,0x00,0x00,0x00]
 # CHECK-EL: jr $7       # encoding: [0x07,0x00,0x3c,0x0f]
 # CHECK-EL: nop         # encoding: [0x00,0x00,0x00,0x00]
 # CHECK-EL: jr $7       # encoding: [0x07,0x00,0x3c,0x0f]
 # CHECK-EL: nop         # encoding: [0x00,0x00,0x00,0x00]
+# CHECK-EL: jalx 1328   # encoding: [0x00,0xf0,0x4c,0x01]
+# CHECK-EL: nop         # encoding: [0x00,0x00,0x00,0x00]
 # CHECK-EL: jals 1328         # encoding: [0x00,0x74,0x98,0x02]
 # CHECK-EL: nop               # encoding: [0x00,0x0c]
 # CHECK-EL: jalrs $ra, $6     # encoding: [0xe6,0x03,0x3c,0x4f]
 # CHECK-EL: nop               # encoding: [0x00,0x0c]
 # CHECK-EL: jalr $25          # encoding: [0xd9,0x45]
 # CHECK-EL: nop               # encoding: [0x00,0x00,0x00,0x00]
 # CHECK-EL: jalr $4, $25      # encoding: [0x99,0x00,0x3c,0x0f]
 # CHECK-EL: nop               # encoding: [0x00,0x00,0x00,0x00]
 #------------------------------------------------------------------------------
 # Big endian
 #------------------------------------------------------------------------------
 # CHECK-EB: j 1328      # encoding: [0xd4,0x00,0x02,0x98]
 # CHECK-EB: nop         # encoding: [0x00,0x00,0x00,0x00]
 # CHECK-EB: jal 1328    # encoding: [0xf4,0x00,0x02,0x98]
 # CHECK-EB: nop         # encoding: [0x00,0x00,0x00,0x00]
 # CHECK-EB: jalr $ra, $6 # encoding: [0x03,0xe6,0x0f,0x3c]
 # CHECK-EB: nop         # encoding: [0x00,0x00,0x00,0x00]
 # CHECK-EB: jr $7       # encoding: [0x00,0x07,0x0f,0x3c]
 # CHECK-EB: nop         # encoding: [0x00,0x00,0x00,0x00]
 # CHECK-EB: jr $7       # encoding: [0x00,0x07,0x0f,0x3c]
 # CHECK-EB: nop         # encoding: [0x00,0x00,0x00,0x00]
+# CHECK-EB: jalx 1328   # encoding: [0xf0,0x00,0x01,0x4c]
+# CHECK-EB: nop         # encoding: [0x00,0x00,0x00,0x00]
 # CHECK-EB: jals 1328         # encoding: [0x74,0x00,0x02,0x98]
 # CHECK-EB: nop               # encoding: [0x0c,0x00]
 # CHECK-EB: jalrs $ra, $6     # encoding: [0x03,0xe6,0x4f,0x3c]
 # CHECK-EB: nop               # encoding: [0x0c,0x00]
 # CHECK-EB: jalr $25          # encoding: [0x45,0xd9]
 # CHECK-EB: nop               # encoding: [0x00,0x00,0x00,0x00]
 # CHECK-EB: jalr $4, $25      # encoding: [0x00,0x99,0x0f,0x3c]
 # CHECK-EB: nop               # encoding: [0x00,0x00,0x00,0x00]
 
      j 1328
      jal 1328
      jalr $ra, $6
      jr $7
      j $7
+     jalx 1328
      jals 1328
      jalrs $ra, $6
      jal $25
      jal $4, $25