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.

llvm-svn: 160277

1 files changed, 29 insertions, 0 deletions

diff --git a/llvm/lib/Target/Mips/MipsMCInstLower.cpp b/llvm/lib/Target/Mips/MipsMCInstLower.cpp
index b6042af619d..c49d5308a5b 100644
--- a/llvm/lib/Target/Mips/MipsMCInstLower.cpp
+++ b/llvm/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;
+  }
+}