From 1d04ca7987ef0abb5be07b11e3bb9c9e756a1fce Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanaka@mips.com>
Date: Fri, 6 Sep 2013 23:40:15 +0000
Subject: [PATCH] [mips] Make "b" (unconditional branch) a pseudo. "b" is an
 assembly idiom, which is equivalent to "beq $zero, $zero, offset".

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190220 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp |  5 ++++-
 lib/Target/Mips/MipsCodeEmitter.cpp             |  4 ++++
 lib/Target/Mips/MipsInstrFormats.td             | 11 -----------
 lib/Target/Mips/MipsInstrInfo.td                |  9 +++++----
 4 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp b/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp
index 755a948f722..231d48520ef 100644
--- a/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp
+++ b/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp
@@ -230,8 +230,11 @@ bool MipsInstPrinter::printAlias(const char *Str, const MCInst &MI,
 bool MipsInstPrinter::printAlias(const MCInst &MI, raw_ostream &OS) {
   switch (MI.getOpcode()) {
   case Mips::BEQ:
+    // beq $zero, $zero, $L2 => b $L2
     // beq $r0, $zero, $L2 => beqz $r0, $L2
-    return isReg<Mips::ZERO>(MI, 1) && printAlias("beqz", MI, 0, 2, OS);
+    return isReg<Mips::ZERO>(MI, 0) && isReg<Mips::ZERO>(MI, 1) &&
+           printAlias("b", MI, 2, OS) ||
+           isReg<Mips::ZERO>(MI, 1) && printAlias("beqz", MI, 0, 2, OS);
   case Mips::BEQ64:
     // beq $r0, $zero, $L2 => beqz $r0, $L2
     return isReg<Mips::ZERO_64>(MI, 1) && printAlias("beqz", MI, 0, 2, OS);
diff --git a/lib/Target/Mips/MipsCodeEmitter.cpp b/lib/Target/Mips/MipsCodeEmitter.cpp
index eed11559256..0f1917a327d 100644
--- a/lib/Target/Mips/MipsCodeEmitter.cpp
+++ b/lib/Target/Mips/MipsCodeEmitter.cpp
@@ -323,6 +323,10 @@ bool MipsCodeEmitter::expandPseudos(MachineBasicBlock::instr_iterator &MI,
     BuildMI(MBB, &*MI, MI->getDebugLoc(), II->get(Mips::SLL), Mips::ZERO)
       .addReg(Mips::ZERO).addImm(0);
     break;
+  case Mips::B:
+    BuildMI(MBB, &*MI, MI->getDebugLoc(), II->get(Mips::BEQ)).addReg(Mips::ZERO)
+      .addReg(Mips::ZERO).addOperand(MI->getOperand(0));
+    break;
   case Mips::JALRPseudo:
     BuildMI(MBB, &*MI, MI->getDebugLoc(), II->get(Mips::JALR), Mips::RA)
       .addReg(MI->getOperand(0).getReg());
diff --git a/lib/Target/Mips/MipsInstrFormats.td b/lib/Target/Mips/MipsInstrFormats.td
index f87d70e403e..c536264d77c 100644
--- a/lib/Target/Mips/MipsInstrFormats.td
+++ b/lib/Target/Mips/MipsInstrFormats.td
@@ -297,17 +297,6 @@ class BGEZ_FM<bits<6> op, bits<5> funct> {
   let Inst{15-0}  = offset;
 }
 
-class B_FM {
-  bits<16> offset;
-
-  bits<32> Inst;
-
-  let Inst{31-26} = 4;
-  let Inst{25-21} = 0;
-  let Inst{20-16} = 0;
-  let Inst{15-0}  = offset;
-}
-
 class SLTI_FM<bits<6> op> : StdArch {
   bits<5> rt;
   bits<5> rs;
diff --git a/lib/Target/Mips/MipsInstrInfo.td b/lib/Target/Mips/MipsInstrInfo.td
index 8b985a81c6e..83c78857992 100644
--- a/lib/Target/Mips/MipsInstrInfo.td
+++ b/lib/Target/Mips/MipsInstrInfo.td
@@ -542,9 +542,9 @@ class JumpFJ<DAGOperand opnd, string opstr, SDPatternOperator operator,
 }
 
 // Unconditional branch
-class UncondBranch<string opstr> :
-  InstSE<(outs), (ins brtarget:$offset), !strconcat(opstr, "\t$offset"),
-         [(br bb:$offset)], IIBranch, FrmI> {
+class UncondBranch<Instruction BEQInst> :
+  PseudoSE<(outs), (ins brtarget:$offset), [(br bb:$offset)], IIBranch>,
+  PseudoInstExpansion<(BEQInst ZERO, ZERO, brtarget:$offset)> {
   let isBranch = 1;
   let isTerminator = 1;
   let isBarrier = 1;
@@ -966,13 +966,13 @@ def SC : SCBase<"sc", GPR32Opnd>, LW_FM<0x38>;
 def J       : JumpFJ<jmptarget, "j", br, bb>, FJ<2>,
               Requires<[RelocStatic, HasStdEnc]>, IsBranch;
 def JR      : IndirectBranch<GPR32Opnd>, MTLO_FM<8>;
-def B       : UncondBranch<"b">, B_FM;
 def BEQ     : CBranch<"beq", seteq, GPR32Opnd>, BEQ_FM<4>;
 def BNE     : CBranch<"bne", setne, GPR32Opnd>, BEQ_FM<5>;
 def BGEZ    : CBranchZero<"bgez", setge, GPR32Opnd>, BGEZ_FM<1, 1>;
 def BGTZ    : CBranchZero<"bgtz", setgt, GPR32Opnd>, BGEZ_FM<7, 0>;
 def BLEZ    : CBranchZero<"blez", setle, GPR32Opnd>, BGEZ_FM<6, 0>;
 def BLTZ    : CBranchZero<"bltz", setlt, GPR32Opnd>, BGEZ_FM<1, 0>;
+def B       : UncondBranch<BEQ>;
 
 def JAL  : JumpLink<"jal">, FJ<3>;
 def JALR : JumpLinkReg<"jalr", GPR32Opnd>, JALR_FM;
@@ -1100,6 +1100,7 @@ def : InstAlias<"mfc0 $rt, $rd", (MFC0 GPR32Opnd:$rt, GPR32Opnd:$rd, 0), 0>;
 def : InstAlias<"mtc0 $rt, $rd", (MTC0 GPR32Opnd:$rt, GPR32Opnd:$rd, 0), 0>;
 def : InstAlias<"mfc2 $rt, $rd", (MFC2 GPR32Opnd:$rt, GPR32Opnd:$rd, 0), 0>;
 def : InstAlias<"mtc2 $rt, $rd", (MTC2 GPR32Opnd:$rt, GPR32Opnd:$rd, 0), 0>;
+def : InstAlias<"b $offset", (BEQ ZERO, ZERO, brtarget:$offset), 0>;
 def : InstAlias<"bnez $rs,$offset",
                 (BNE GPR32Opnd:$rs, ZERO, brtarget:$offset), 0>;
 def : InstAlias<"beqz $rs,$offset",
-- 
2.34.1