MicroMIPS Compact Branch Instructions BEQZC and BNEZC

[jkolek]

Summary

Implement microMIPS compact branch instructions BEQZC and BNEZC.

[jkolek]

lib/Target/Mips/MicroMipsInstrInfo.td

32

These instructions doesn't have specified selection pattern, the usage implementation is in http://reviews.llvm.org/D3566.

[dsanders]

LGTM

[jkolek]

Closed by commit rL215636 (authored by zjovanovic).

lib/Target/Mips/MicroMipsInstrFormats.td

   let Inst{10-6}  = fr;
   let Inst{5-0}   = funct;
 }
+
+class COMPACT_BRANCH_FM_MM<bits<5> funct> {
+  bits<5>  rs;
+  bits<16> offset;
+
+  bits<32> Inst;
+
+  let Inst{31-26} = 0x10;
+  let Inst{25-21} = funct;
+  let Inst{20-16} = rs;
+  let Inst{15-0}  = offset;
+}

lib/Target/Mips/MicroMipsInstrInfo.td

   let DecoderMethod = "DecodeBranchTargetMM";
 }
 
+class CompactBranchMM<string opstr, DAGOperand opnd, PatFrag cond_op,
+                      RegisterOperand RO> :
+  InstSE<(outs), (ins RO:$rs, opnd:$offset),
+         !strconcat(opstr, "\t$rs, $offset"), [], IIBranch, FrmI> {
+  let isBranch = 1;
+  let isTerminator = 1;
+  let hasDelaySlot = 0;
+  let Defs = [AT];
+}
+
 let canFoldAsLoad = 1 in
 class LoadLeftRightMM<string opstr, SDNode OpNode, RegisterOperand RO,
                       Operand MemOpnd> :

          NoItinerary, FrmOther, opstr>;
 
 let DecoderNamespace = "MicroMips", Predicates = [InMicroMips] in {
+  /// Compact Branch Instructions
+  def BEQZC_MM : CompactBranchMM<"beqzc", brtarget_mm, seteq, GPR32Opnd>,
+                 COMPACT_BRANCH_FM_MM<0x7>;
+  def BNEZC_MM : CompactBranchMM<"bnezc", brtarget_mm, setne, GPR32Opnd>,
+                 COMPACT_BRANCH_FM_MM<0x5>;
+
   /// Arithmetic Instructions (ALU Immediate)
   def ADDiu_MM : MMRel, ArithLogicI<"addiu", simm16, GPR32Opnd>,
                  ADDI_FM_MM<0xc>;

test/MC/Mips/micromips-compact-branch-instructions.s

+# RUN: llvm-mc %s -triple=mipsel -show-encoding -mattr=micromips | \
+# RUN: FileCheck -check-prefix=CHECK-EL %s
+# RUN: llvm-mc %s -triple=mips -show-encoding -mattr=micromips | \
+# RUN: FileCheck -check-prefix=CHECK-EB %s
+# Check that the assembler can handle the documented syntax
+# for compact branch instructions.
+#------------------------------------------------------------------------------
+# MicroMIPS 32-bit Compact Branch Instructions
+#------------------------------------------------------------------------------
+# Little endian
+#------------------------------------------------------------------------------
+# CHECK-EL: beqzc   $9, 1332        # encoding: [0xe9,0x40,0x9a,0x02]
+# CHECK-EL: bnezc   $9, 1332        # encoding: [0xa9,0x40,0x9a,0x02]
+#------------------------------------------------------------------------------
+# Big endian
+#------------------------------------------------------------------------------
+# CHECK-EB: beqzc   $9, 1332        # encoding: [0x40,0xe9,0x02,0x9a]
+# CHECK-EB: bnezc   $9, 1332        # encoding: [0x40,0xa9,0x02,0x9a]
+
+    beqzc   $9, 1332
+    bnezc   $9, 1332