Doubleword Shift Left Logical Plus 32

Mips shift instructions DSLL, DSRL and DSRA are transformed into
DSLL32, DSRL32 and DSRA32 respectively if the shift amount is between
32 and 63

Here is a description of DSLL:

Purpose: Doubleword Shift Left Logical Plus 32
To execute a left-shift of a doubleword by a fixed amount--32 to 63 bits

Description: GPR[rd] <- GPR[rt] << (sa+32)

The 64-bit doubleword contents of GPR rt are shifted left, inserting
 zeros into the emptied bits; the result is placed in
GPR rd. The bit-shift amount in the range 0 to 31 is specified by sa.

This patch implements the direct object output of these instructions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160277 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/Mips/Mips64InstrInfo.td

@@ -109,6 +109,11 @@ def DSRA     : shift_rotate_imm64<0x3b, 0x00, "dsra", sra>;
 def DSLLV    : shift_rotate_reg<0x14, 0x00, "dsllv", shl, CPU64Regs>;
 def DSRLV    : shift_rotate_reg<0x16, 0x00, "dsrlv", srl, CPU64Regs>;
 def DSRAV    : shift_rotate_reg<0x17, 0x00, "dsrav", sra, CPU64Regs>;
+let Pattern = []<dag> in {
+def DSLL32   : shift_rotate_imm64<0x3c, 0x00, "dsll32", shl>;
+def DSRL32   : shift_rotate_imm64<0x3e, 0x00, "dsrl32", srl>;
+def DSRA32   : shift_rotate_imm64<0x3f, 0x00, "dsra32", sra>;
+}
 }
 // Rotate Instructions
 let Predicates = [HasMips64r2, HasStandardEncoding],

lib/Target/Mips/MipsAsmPrinter.cpp

@@ -13,9 +13,10 @@
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "mips-asm-printer"
-#include "MipsAsmPrinter.h"
 #include "Mips.h"
+#include "MipsAsmPrinter.h"
 #include "MipsInstrInfo.h"
+#include "MipsMCInstLower.h"
 #include "InstPrinter/MipsInstPrinter.h"
 #include "MCTargetDesc/MipsBaseInfo.h"
 #include "llvm/ADT/SmallString.h"
@@ -57,6 +58,25 @@ void MipsAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     return;
   }
 
+  // Direct object specific instruction lowering
+  if (!OutStreamer.hasRawTextSupport())
+    switch (MI->getOpcode()) {
+    case Mips::DSLL:
+    case Mips::DSRL:
+    case Mips::DSRA:
+      assert(MI->getNumOperands() == 3 &&
+             "Invalid no. of machine operands for shift!");
+      assert(MI->getOperand(2).isImm());
+      int64_t Shift = MI->getOperand(2).getImm();
+      if (Shift > 31) {
+        MCInst TmpInst0;
+        MCInstLowering.LowerLargeShift(MI, TmpInst0, Shift - 32);
+        OutStreamer.EmitInstruction(TmpInst0);
+        return;
+      }
+      break;
+    }
+
   MachineBasicBlock::const_instr_iterator I = MI;
   MachineBasicBlock::const_instr_iterator E = MI->getParent()->instr_end();
 

lib/Target/Mips/MipsMCInstLower.cpp

@@ -158,3 +158,32 @@ void MipsMCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {
       OutMI.addOperand(MCOp);
   }
 }
+
+// If the D<shift> instruction has a shift amount that is greater
+// than 31 (checked in calling routine), lower it to a D<shift>32 instruction
+void MipsMCInstLower::LowerLargeShift(const MachineInstr *MI,
+                                      MCInst& Inst,
+                                      int64_t Shift) {
+  // rt
+  Inst.addOperand(LowerOperand(MI->getOperand(0)));
+  // rd
+  Inst.addOperand(LowerOperand(MI->getOperand(1)));
+  // saminus32
+  Inst.addOperand(MCOperand::CreateImm(Shift));
+
+  switch (MI->getOpcode()) {
+  default:
+    // Calling function is not synchronized
+    llvm_unreachable("Unexpected shift instruction");
+    break;
+  case Mips::DSLL:
+    Inst.setOpcode(Mips::DSLL32);
+    break;
+  case Mips::DSRL:
+    Inst.setOpcode(Mips::DSRL32);
+    break;
+  case Mips::DSRA:
+    Inst.setOpcode(Mips::DSRA32);
+    break;
+  }
+}

lib/Target/Mips/MipsMCInstLower.h

@@ -33,6 +33,8 @@ public:
   MipsMCInstLower(MipsAsmPrinter &asmprinter);
   void Initialize(Mangler *mang, MCContext *C);
   void Lower(const MachineInstr *MI, MCInst &OutMI) const;
+  void LowerLargeShift(const MachineInstr *MI, MCInst &Inst, int64_t Shift);
+
 private:
   MCOperand LowerSymbolOperand(const MachineOperand &MO,
                                MachineOperandType MOTy, unsigned Offset) const;

test/MC/Mips/mips64shift.ll

@@ -0,0 +1,45 @@
+; RUN: llc -march=mips64el -filetype=obj -mcpu=mips64r2 %s -o - | llvm-objdump -disassemble -triple mips64el - | FileCheck %s
+
+
+define i64 @f3(i64 %a0) nounwind readnone {
+entry:
+; CHECK: dsll ${{[0-9]+}}, ${{[0-9]+}}, 10
+  %shl = shl i64 %a0, 10
+  ret i64 %shl
+}
+
+define i64 @f4(i64 %a0) nounwind readnone {
+entry:
+; CHECK: dsra ${{[0-9]+}}, ${{[0-9]+}}, 10
+  %shr = ashr i64 %a0, 10
+  ret i64 %shr
+}
+
+define i64 @f5(i64 %a0) nounwind readnone {
+entry:
+; CHECK: dsrl ${{[0-9]+}}, ${{[0-9]+}}, 10
+  %shr = lshr i64 %a0, 10
+  ret i64 %shr
+}
+
+define i64 @f6(i64 %a0) nounwind readnone {
+entry:
+; CHECK: dsll32 ${{[0-9]+}}, ${{[0-9]+}}, 8
+  %shl = shl i64 %a0, 40
+  ret i64 %shl
+}
+
+define i64 @f7(i64 %a0) nounwind readnone {
+entry:
+; CHECK: dsra32 ${{[0-9]+}}, ${{[0-9]+}}, 8
+  %shr = ashr i64 %a0, 40
+  ret i64 %shr
+}
+
+define i64 @f8(i64 %a0) nounwind readnone {
+entry:
+; CHECK: dsrl32 ${{[0-9]+}}, ${{[0-9]+}}, 8
+  %shr = lshr i64 %a0, 40
+  ret i64 %shr
+}
+