[mips] Print instructions "beq", "bne" and "or" using assembler pseudo

instructions "beqz", "bnez" and "move", when possible.

beq $2, $zero, $L1 => beqz $2, $L1
bne $2, $zero, $L1 => bnez $2, $L1
or  $2, $3, $zero  => move $2, $3



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187229 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 57 insertions, 1 deletions

diff --git a/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp b/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp
index fc23cd3..27fbb1a 100644
--- a/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp
+++ b/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp
@@ -26,6 +26,12 @@ using namespace llvm;
 #define PRINT_ALIAS_INSTR
 #include "MipsGenAsmWriter.inc"
 
+template<unsigned R>
+static bool isReg(const MCInst &MI, unsigned OpNo) {
+  assert(MI.getOperand(OpNo).isReg() && "Register operand expected.");
+  return MI.getOperand(OpNo).getReg() == R;
+}
+
 const char* Mips::MipsFCCToString(Mips::CondCode CC) {
   switch (CC) {
   case FCOND_F:
@@ -80,7 +86,7 @@ void MipsInstPrinter::printInst(const MCInst *MI, raw_ostream &O,
   }
 
   // Try to print any aliases first.
-  if (!printAliasInstr(MI, O))
+  if (!printAliasInstr(MI, O) && !printAlias(*MI, O))
     printInstruction(MI, O);
   printAnnotation(O, Annot);
 
@@ -209,3 +215,47 @@ printFCCOperand(const MCInst *MI, int opNum, raw_ostream &O) {
   const MCOperand& MO = MI->getOperand(opNum);
   O << MipsFCCToString((Mips::CondCode)MO.getImm());
 }
+
+bool MipsInstPrinter::printAlias(const char *Str, const MCInst &MI,
+                                 unsigned OpNo, raw_ostream &OS) {
+  OS << "\t" << Str << "\t";
+  printOperand(&MI, OpNo, OS);
+  return true;
+}
+
+bool MipsInstPrinter::printAlias(const char *Str, const MCInst &MI,
+                                 unsigned OpNo0, unsigned OpNo1,
+                                 raw_ostream &OS) {
+  printAlias(Str, MI, OpNo0, OS);
+  OS << ", ";
+  printOperand(&MI, OpNo1, OS);
+  return true;
+}
+
+bool MipsInstPrinter::printAlias(const MCInst &MI, raw_ostream &OS) {
+  switch (MI.getOpcode()) {
+  case Mips::BEQ:
+    if (isReg<Mips::ZERO>(MI, 1) && printAlias("beqz", MI, 0, 2, OS))
+      return true;
+    break;
+  case Mips::BEQ64:
+    if (isReg<Mips::ZERO_64>(MI, 1) && printAlias("beqz", MI, 0, 2, OS))
+      return true;
+    break;
+  case Mips::BNE:
+    if (isReg<Mips::ZERO>(MI, 1) && printAlias("bnez", MI, 0, 2, OS))
+      return true;
+    break;
+  case Mips::BNE64:
+    if (isReg<Mips::ZERO_64>(MI, 1) && printAlias("bnez", MI, 0, 2, OS))
+      return true;
+    break;
+  case Mips::OR:
+    if (isReg<Mips::ZERO>(MI, 2) && printAlias("move", MI, 0, 1, OS))
+      return true;
+    break;
+  default: return false;
+  }
+
+  return false;
+}
diff --git a/lib/Target/Mips/InstPrinter/MipsInstPrinter.h b/lib/Target/Mips/InstPrinter/MipsInstPrinter.h
index d1b561f..783db73 100644
--- a/lib/Target/Mips/InstPrinter/MipsInstPrinter.h
+++ b/lib/Target/Mips/InstPrinter/MipsInstPrinter.h
@@ -97,6 +97,12 @@ private:
   void printMemOperand(const MCInst *MI, int opNum, raw_ostream &O);
   void printMemOperandEA(const MCInst *MI, int opNum, raw_ostream &O);
   void printFCCOperand(const MCInst *MI, int opNum, raw_ostream &O);
+
+  bool printAlias(const char *Str, const MCInst &MI, unsigned OpNo,
+                  raw_ostream &OS);
+  bool printAlias(const char *Str, const MCInst &MI, unsigned OpNo0,
+                  unsigned OpNo1, raw_ostream &OS);
+  bool printAlias(const MCInst &MI, raw_ostream &OS);
 };
 } // end namespace llvm