[mips] Remove codegen support for branch likely instructions.

[sdardis]

Summary

This patch disables codegen support for branch likely instructions to
address a potential bug. These branches were unselectable as
they had the same patterns as the normal branches but came after them
when ISel was concerned.

The branch likely instructions were marked as having no delay
slots when they have annulling delay slots. The delay slot filler
does not currently handle annulling delay slot branches, so this
would lead to wrong codegen if these branches were generated.

[atanasyan]

LGTM

lib/Target/Mips/MipsInstrFPU.td

class SWXC1_FT<string opstr, RegisterOperand DRC,
   InstSE<(outs), (ins DRC:$fs, PtrRC:$base, PtrRC:$index),
          !strconcat(opstr, "\t$fs, ${index}(${base})"),
          [(OpNode DRC:$fs, (add iPTR:$base, iPTR:$index))], Itin,
          FrmFI, opstr>, HARDFLOAT {
   let AddedComplexity = 20;
 }
 
 class BC1F_FT<string opstr, DAGOperand opnd, InstrItinClass Itin,
-              SDPatternOperator Op = null_frag, bit DelaySlot = 1> :
+              SDPatternOperator Op = null_frag> :
   InstSE<(outs), (ins FCCRegsOpnd:$fcc, opnd:$offset),
          !strconcat(opstr, "\t$fcc, $offset"),
          [(MipsFPBrcond Op, FCCRegsOpnd:$fcc, bb:$offset)], Itin,
          FrmFI, opstr>, HARDFLOAT {
   let isBranch = 1;
   let isTerminator = 1;
-  let hasDelaySlot = DelaySlot;
+  let hasDelaySlot = 1;
+  let Defs = [AT];
+  let hasFCCRegOperand = 1;
+}
+
+class BC1XL_FT<string opstr, DAGOperand opnd, InstrItinClass Itin> :
+  InstSE<(outs), (ins FCCRegsOpnd:$fcc, opnd:$offset),
+         !strconcat(opstr, "\t$fcc, $offset"), [], Itin,
+         FrmFI, opstr>, HARDFLOAT {
+  let isBranch = 1;
+  let isTerminator = 1;
+  let hasDelaySlot = 1;
   let Defs = [AT];
   let hasFCCRegOperand = 1;
 }
 
 class CEQS_FT<string typestr, RegisterClass RC, InstrItinClass Itin,
               SDPatternOperator OpNode = null_frag>  :
   InstSE<(outs), (ins RC:$fs, RC:$ft, condcode:$cond),
          !strconcat("c.$cond.", typestr, "\t$fs, $ft"),

 //===----------------------------------------------------------------------===//
 // Mips branch codes. These correspond to condcode in MipsInstrInfo.h.
 // They must be kept in synch.
 def MIPS_BRANCH_F  : PatLeaf<(i32 0)>;
 def MIPS_BRANCH_T  : PatLeaf<(i32 1)>;
 
 def BC1F : MMRel, BC1F_FT<"bc1f", brtarget, II_BC1F, MIPS_BRANCH_F>,
            BC1F_FM<0, 0>, ISA_MIPS1_NOT_32R6_64R6;
-def BC1FL : MMRel, BC1F_FT<"bc1fl", brtarget, II_BC1FL, MIPS_BRANCH_F, 0>,
+def BC1FL : MMRel, BC1XL_FT<"bc1fl", brtarget, II_BC1FL>,
             BC1F_FM<1, 0>, ISA_MIPS2_NOT_32R6_64R6;
 def BC1T : MMRel, BC1F_FT<"bc1t", brtarget, II_BC1T, MIPS_BRANCH_T>,
            BC1F_FM<0, 1>, ISA_MIPS1_NOT_32R6_64R6;
-def BC1TL : MMRel, BC1F_FT<"bc1tl", brtarget, II_BC1TL, MIPS_BRANCH_T, 0>,
+def BC1TL : MMRel, BC1XL_FT<"bc1tl", brtarget, II_BC1TL>,
             BC1F_FM<1, 1>, ISA_MIPS2_NOT_32R6_64R6;
 
 /// Floating Point Compare
 let AdditionalPredicates = [NotInMicroMips] in {
   def FCMP_S32 : MMRel, CEQS_FT<"s", FGR32, II_C_CC_S, MipsFPCmp>, CEQS_FM<16>,
                  ISA_MIPS1_NOT_32R6_64R6 {
 
   // FIXME: This is a required to work around the fact that these instructions

lib/Target/Mips/MipsInstrInfo.td

class SW_FT3<string opstr, RegisterOperand RC, InstrItinClass Itin,
   InstSE<(outs), (ins RC:$rt, mem:$addr), !strconcat(opstr, "\t$rt, $addr"),
          [(OpNode RC:$rt, addrDefault:$addr)], Itin, FrmFI, opstr> {
   let DecoderMethod = "DecodeFMem3";
   let mayStore = 1;
 }
 
 // Conditional Branch
 class CBranch<string opstr, DAGOperand opnd, PatFrag cond_op,
-              RegisterOperand RO, bit DelaySlot = 1> :
+              RegisterOperand RO> :
   InstSE<(outs), (ins RO:$rs, RO:$rt, opnd:$offset),
          !strconcat(opstr, "\t$rs, $rt, $offset"),
          [(brcond (i32 (cond_op RO:$rs, RO:$rt)), bb:$offset)], II_BCC,
          FrmI, opstr> {
   let isBranch = 1;
   let isTerminator = 1;
-  let hasDelaySlot = DelaySlot;
+  let hasDelaySlot = 1;
+  let Defs = [AT];
+  bit isCTI = 1;
+}
+
+class CBranchLikely<string opstr, DAGOperand opnd, RegisterOperand RO> :
+  InstSE<(outs), (ins RO:$rs, RO:$rt, opnd:$offset),
+         !strconcat(opstr, "\t$rs, $rt, $offset"), [], II_BCC, FrmI, opstr> {
+  let isBranch = 1;
+  let isTerminator = 1;
+  let hasDelaySlot = 1;
   let Defs = [AT];
   bit isCTI = 1;
 }
 
 class CBranchZero<string opstr, DAGOperand opnd, PatFrag cond_op,
-                  RegisterOperand RO, bit DelaySlot = 1> :
+                  RegisterOperand RO> :
   InstSE<(outs), (ins RO:$rs, opnd:$offset),
          !strconcat(opstr, "\t$rs, $offset"),
          [(brcond (i32 (cond_op RO:$rs, 0)), bb:$offset)], II_BCCZ,
          FrmI, opstr> {
   let isBranch = 1;
   let isTerminator = 1;
-  let hasDelaySlot = DelaySlot;
+  let hasDelaySlot = 1;
+  let Defs = [AT];
+  bit isCTI = 1;
+}
+
+class CBranchZeroLikely<string opstr, DAGOperand opnd, RegisterOperand RO> :
+  InstSE<(outs), (ins RO:$rs, opnd:$offset),
+         !strconcat(opstr, "\t$rs, $offset"), [], II_BCCZ, FrmI, opstr> {
+  let isBranch = 1;
+  let isTerminator = 1;
+  let hasDelaySlot = 1;
   let Defs = [AT];
   bit isCTI = 1;
 }
 
 // SetCC
 class SetCC_R<string opstr, PatFrag cond_op, RegisterOperand RO> :
   InstSE<(outs GPR32Opnd:$rd), (ins RO:$rs, RO:$rt),
          !strconcat(opstr, "\t$rd, $rs, $rt"),
class JumpLinkRegPseudo<RegisterOperand RO, Instruction JALRInst,
     PseudoSE<(outs), (ins RO:$rs), [(MipsJmpLink RO:$rs)], II_JALR>,
     PseudoInstExpansion<(JALRInst RetReg, ResRO:$rs)>;
 
   class JumpLinkReg<string opstr, RegisterOperand RO>:
     InstSE<(outs RO:$rd), (ins RO:$rs), !strconcat(opstr, "\t$rd, $rs"),
            [], II_JALR, FrmR, opstr>;
 
   class BGEZAL_FT<string opstr, DAGOperand opnd,
-                  RegisterOperand RO, bit DelaySlot = 1> :
+                  RegisterOperand RO> :
     InstSE<(outs), (ins RO:$rs, opnd:$offset),
            !strconcat(opstr, "\t$rs, $offset"), [], II_BCCZAL, FrmI, opstr> {
-    let hasDelaySlot = DelaySlot;
+    let hasDelaySlot = 1;
   }
 
 }
 
 let isCall = 1, isTerminator = 1, isReturn = 1, isBarrier = 1, hasDelaySlot = 1,
     hasExtraSrcRegAllocReq = 1, isCTI = 1, Defs = [AT] in {
   class TailCall<Instruction JumpInst, DAGOperand Opnd> :
     PseudoSE<(outs), (ins calltarget:$target), [], II_J>,

 def SC : SCBase<"sc", GPR32Opnd>, LW_FM<0x38>, PTR_32, ISA_MIPS2_NOT_32R6_64R6;
 }
 
 /// Jump and Branch Instructions
 def J       : MMRel, JumpFJ<jmptarget, "j", br, bb, "j">, FJ<2>,
               AdditionalRequires<[RelocNotPIC]>, IsBranch;
 def JR      : MMRel, IndirectBranch<"jr", GPR32Opnd>, MTLO_FM<8>, ISA_MIPS1_NOT_32R6_64R6; 
 def BEQ     : MMRel, CBranch<"beq", brtarget, seteq, GPR32Opnd>, BEQ_FM<4>;
-def BEQL    : MMRel, CBranch<"beql", brtarget, seteq, GPR32Opnd, 0>,
+def BEQL    : MMRel, CBranchLikely<"beql", brtarget, GPR32Opnd>,
               BEQ_FM<20>, ISA_MIPS2_NOT_32R6_64R6;
 def BNE     : MMRel, CBranch<"bne", brtarget, setne, GPR32Opnd>, BEQ_FM<5>;
-def BNEL    : MMRel, CBranch<"bnel", brtarget, setne, GPR32Opnd, 0>,
+def BNEL    : MMRel, CBranchLikely<"bnel", brtarget, GPR32Opnd>,
               BEQ_FM<21>, ISA_MIPS2_NOT_32R6_64R6;
 def BGEZ    : MMRel, CBranchZero<"bgez", brtarget, setge, GPR32Opnd>,
               BGEZ_FM<1, 1>;
-def BGEZL   : MMRel, CBranchZero<"bgezl", brtarget, setge, GPR32Opnd, 0>,
+def BGEZL   : MMRel, CBranchZeroLikely<"bgezl", brtarget, GPR32Opnd>,
               BGEZ_FM<1, 3>, ISA_MIPS2_NOT_32R6_64R6;
 def BGTZ    : MMRel, CBranchZero<"bgtz", brtarget, setgt, GPR32Opnd>,
               BGEZ_FM<7, 0>;
-def BGTZL   : MMRel, CBranchZero<"bgtzl", brtarget, setgt, GPR32Opnd, 0>,
+def BGTZL   : MMRel, CBranchZeroLikely<"bgtzl", brtarget, GPR32Opnd>,
               BGEZ_FM<23, 0>, ISA_MIPS2_NOT_32R6_64R6;
 def BLEZ    : MMRel, CBranchZero<"blez", brtarget, setle, GPR32Opnd>,
               BGEZ_FM<6, 0>;
-def BLEZL   : MMRel, CBranchZero<"blezl", brtarget, setle, GPR32Opnd, 0>,
+def BLEZL   : MMRel, CBranchZeroLikely<"blezl", brtarget, GPR32Opnd>,
               BGEZ_FM<22, 0>, ISA_MIPS2_NOT_32R6_64R6;
 def BLTZ    : MMRel, CBranchZero<"bltz", brtarget, setlt, GPR32Opnd>,
               BGEZ_FM<1, 0>;
-def BLTZL   : MMRel, CBranchZero<"bltzl", brtarget, setlt, GPR32Opnd, 0>,
+def BLTZL   : MMRel, CBranchZeroLikely<"bltzl", brtarget, GPR32Opnd>,
               BGEZ_FM<1, 2>, ISA_MIPS2_NOT_32R6_64R6;
 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>;
 }
 
 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>,
+def BGEZALL : MMRel, BGEZAL_FT<"bgezall", brtarget, GPR32Opnd>,
               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>,
+def BLTZALL : MMRel, BGEZAL_FT<"bltzall", brtarget, GPR32Opnd>,
               BGEZAL_FM<0x12>, ISA_MIPS2_NOT_32R6_64R6;
 def BAL_BR : BAL_BR_Pseudo<BGEZAL>;
 
 let Predicates = [NotInMicroMips] in { 
   def TAILCALL : TailCall<J, jmptarget>;
 }
 
 def TAILCALLREG : TailCallReg<GPR32Opnd>;

test/MC/Mips/mips-jump-delay-slots.s

-# Verify that every branch and jump instruction is followed by a delay slot
-# except for the branch likely instructions.
+# Verify that every branch and jump instruction is followed by a delay slot.
 #
 # RUN: llvm-mc %s -triple=mips-unknown-linux -mcpu=mips32r2 | FileCheck %s
 
         .set noat
         # CHECK: b 1332
         # CHECK: nop
         b 1332
         # CHECK: bc1f 1332
# RUN: llvm-mc %s -triple=mips-unknown-linux -mcpu=mips32r2 | FileCheck %s
         # CHECK: bnez $11, 1332
         # CHECK: nop
         bnez $11,1332
         # CHECK: beqz $11, 1332
         # CHECK: nop
         beqz $11,1332
 
         # CHECK: bc1fl 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         bc1fl 1332
         # CHECK: bc1fl 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         bc1fl $fcc0, 1332
         # CHECK: bc1fl $fcc3, 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         bc1fl $fcc3, 1332
         # CHECK: bc1tl 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         bc1tl 1332
         # CHECK: bc1tl 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         bc1tl $fcc0, 1332
         # CHECK: bc1tl $fcc3, 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         bc1tl $fcc3, 1332
         # CHECK: beql $9, $6, 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         beql $9,$6,1332
         # CHECK: beql $9, $zero, 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         beqzl $9,1332
         # CHECK: bnel $9, $6, 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         bnel $9,$6,1332
         # CHECK: bnel $9, $zero, 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         bnezl $9,1332
         # CHECK: bgezl $6, 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         bgezl $6,1332
         # CHECK: bgtzl $6, 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         bgtzl $6,1332
         # CHECK: blezl $6, 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         blezl $6,1332
         # CHECK: bltzl $6, 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         bltzl $6,1332
         # CHECK: bgezall $6, 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         bgezall $6,1332
         # CHECK: bltzall $6, 1332
-        # CHECK-NOT: nop
+        # CHECK: nop
         bltzall $6,1332
 
         # CHECK: j 1328
         # CHECK: nop
         j 1328
         # CHECK: jal 1328
         # CHECK: nop
         jal 1328