The mips 64bit instructions DSLL, DSRA, DSRL, DEXT and DINS get transformed by the assembler or through codegen direct object output to other variants based on the value of the immediate values of the operands.

If the code is generated as assembler, this transformation does not occur assuming that it will occur later in the assembler.

This code was originally called from  MipsAsmPrinter.cpp and we needed to check for OutStreamer.hasRawTextSupport(). This was not a good place for it and has been moved to MCTargetDesc/MipsMCCodeEmitter.cpp where both direct object and the assembler use it it automagically.

The test cases have been checked in for a number of weeks now.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165067 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/Mips/CMakeLists.txt

@@ -22,7 +22,6 @@ add_llvm_target(MipsCodeGen
   MipsAsmPrinter.cpp
   MipsCodeEmitter.cpp
   MipsDelaySlotFiller.cpp
-  MipsDirectObjLower.cpp
   MipsELFWriterInfo.cpp
   MipsJITInfo.cpp
   MipsInstrInfo.cpp

lib/Target/Mips/MCTargetDesc/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_llvm_library(LLVMMipsDesc
   MipsAsmBackend.cpp
+  MipsDirectObjLower.cpp
   MipsMCAsmInfo.cpp
   MipsMCCodeEmitter.cpp
   MipsMCTargetDesc.cpp

lib/Target/Mips/MCTargetDesc/MipsDirectObjLower.cpp

@@ -11,8 +11,8 @@
 // left to the assembler to lower such as large shifts.
 //
 //===----------------------------------------------------------------------===//
-#include "MipsDirectObjLower.h"
 #include "MipsInstrInfo.h"
+#include "MCTargetDesc/MipsDirectObjLower.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCStreamer.h"
 
@@ -25,32 +25,28 @@ void Mips::LowerLargeShift(MCInst& Inst) {
   assert(Inst.getNumOperands() == 3 && "Invalid no. of operands for shift!");
   assert(Inst.getOperand(2).isImm());
 
-  bool isLarge = false;
-  int64_t Shift;
-  Shift = Inst.getOperand(2).getImm();
-  if (Shift > 31) {
-    Shift -= 32;
-    isLarge = true;
-  }
+  int64_t Shift = Inst.getOperand(2).getImm();
+  if (Shift <= 31)
+    return; // Do nothing
+  Shift -= 32;
 
   // saminus32
-  (Inst.getOperand(2)).setImm(Shift);
+  Inst.getOperand(2).setImm(Shift);
 
-  if (isLarge)
-    switch (Inst.getOpcode()) {
-    default:
-      // Calling function is not synchronized
-      llvm_unreachable("Unexpected shift instruction");
-    case Mips::DSLL:
-      Inst.setOpcode(Mips::DSLL32);
-      return;
-    case Mips::DSRL:
-      Inst.setOpcode(Mips::DSRL32);
-      return;
-    case Mips::DSRA:
-      Inst.setOpcode(Mips::DSRA32);
-      return;
-    }
+  switch (Inst.getOpcode()) {
+  default:
+    // Calling function is not synchronized
+    llvm_unreachable("Unexpected shift instruction");
+  case Mips::DSLL:
+    Inst.setOpcode(Mips::DSLL32);
+    return;
+  case Mips::DSRL:
+    Inst.setOpcode(Mips::DSRL32);
+    return;
+  case Mips::DSRA:
+    Inst.setOpcode(Mips::DSRA32);
+    return;
+  }
 }
 
 // Pick a DEXT or DINS instruction variant based on the pos and size operands
@@ -70,17 +66,16 @@ void Mips::LowerDextDins(MCInst& InstIn) {
   int64_t size = InstIn.getOperand(3).getImm();
 
   if (size <= 32) {
-    if ((pos < 32)) { // DEXT/DINS, do nothing
+    if (pos < 32)  // DEXT/DINS, do nothing
       return;
-    } else { // DEXTU/DINSU
-      InstIn.getOperand(2).setImm(pos - 32);
-      InstIn.setOpcode((Opcode == Mips::DEXT) ? Mips::DEXTU : Mips::DINSU);
-      return;
-    }
-  } else { // DEXTM/DINSM
-    assert(pos < 32 && "DEXT/DINS cannot have both size and pos > 32");
-    InstIn.getOperand(3).setImm(size - 32);
-    InstIn.setOpcode((Opcode == Mips::DEXT) ? Mips::DEXTM : Mips::DINSM);
+    // DEXTU/DINSU
+    InstIn.getOperand(2).setImm(pos - 32);
+    InstIn.setOpcode((Opcode == Mips::DEXT) ? Mips::DEXTU : Mips::DINSU);
     return;
   }
+  // DEXTM/DINSM
+  assert(pos < 32 && "DEXT/DINS cannot have both size and pos > 32");
+  InstIn.getOperand(3).setImm(size - 32);
+  InstIn.setOpcode((Opcode == Mips::DEXT) ? Mips::DEXTM : Mips::DINSM);
+  return;
 }

lib/Target/Mips/MCTargetDesc/MipsMCCodeEmitter.cpp

@@ -13,6 +13,7 @@
 //
 #define DEBUG_TYPE "mccodeemitter"
 #include "MCTargetDesc/MipsBaseInfo.h"
+#include "MCTargetDesc/MipsDirectObjLower.h"
 #include "MCTargetDesc/MipsFixupKinds.h"
 #include "MCTargetDesc/MipsMCTargetDesc.h"
 #include "llvm/ADT/APFloat.h"
@@ -109,16 +110,35 @@ void MipsMCCodeEmitter::
 EncodeInstruction(const MCInst &MI, raw_ostream &OS,
                   SmallVectorImpl<MCFixup> &Fixups) const
 {
-  uint32_t Binary = getBinaryCodeForInstr(MI, Fixups);
+
+  // Non-pseudo instructions that get changed for direct object
+  // only based on operand values.
+  // If this list of instructions get much longer we will move
+  // the check to a function call. Until then, this is more efficient.
+  MCInst TmpInst = MI;
+  switch (MI.getOpcode()) {
+  // If shift amount is >= 32 it the inst needs to be lowered further
+  case Mips::DSLL:
+  case Mips::DSRL:
+  case Mips::DSRA:
+    Mips::LowerLargeShift(TmpInst);
+    break;
+    // Double extract instruction is chosen by pos and size operands
+  case Mips::DEXT:
+  case Mips::DINS:
+    Mips::LowerDextDins(TmpInst);
+  }
+
+  uint32_t Binary = getBinaryCodeForInstr(TmpInst, Fixups);
 
   // Check for unimplemented opcodes.
-  // Unfortunately in MIPS both NOT and SLL will come in with Binary == 0
+  // Unfortunately in MIPS both NOP and SLL will come in with Binary == 0
   // so we have to special check for them.
-  unsigned Opcode = MI.getOpcode();
+  unsigned Opcode = TmpInst.getOpcode();
   if ((Opcode != Mips::NOP) && (Opcode != Mips::SLL) && !Binary)
     llvm_unreachable("unimplemented opcode in EncodeInstruction()");
 
-  const MCInstrDesc &Desc = MCII.get(MI.getOpcode());
+  const MCInstrDesc &Desc = MCII.get(TmpInst.getOpcode());
   uint64_t TSFlags = Desc.TSFlags;
 
   // Pseudo instructions don't get encoded and shouldn't be here

lib/Target/Mips/MipsAsmPrinter.cpp

@@ -15,7 +15,6 @@
 #define DEBUG_TYPE "mips-asm-printer"
 #include "Mips.h"
 #include "MipsAsmPrinter.h"
-#include "MipsDirectObjLower.h"
 #include "MipsInstrInfo.h"
 #include "MipsMCInstLower.h"
 #include "InstPrinter/MipsInstPrinter.h"
@@ -77,22 +76,6 @@ void MipsAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     MCInst TmpInst0;
     MCInstLowering.Lower(I++, TmpInst0);
 
-    // Direct object specific instruction lowering
-    if (!OutStreamer.hasRawTextSupport()){
-      switch (TmpInst0.getOpcode()) {
-      // If shift amount is >= 32 it the inst needs to be lowered further
-      case Mips::DSLL:
-      case Mips::DSRL:
-      case Mips::DSRA:
-        Mips::LowerLargeShift(TmpInst0);
-        break;
-        // Double extract instruction is chosen by pos and size operands
-      case Mips::DEXT:
-      case Mips::DINS:
-        Mips::LowerDextDins(TmpInst0);
-      }
-    }
-
     OutStreamer.EmitInstruction(TmpInst0);
   } while ((I != E) && I->isInsideBundle()); // Delay slot check
 }