Lower 64-bit immediates using MipsAnalyzeImmediate that has just been added.

Add a test case to show fewer instructions are needed to load an immediate
with the new way of loading immediates.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148908 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 42 insertions, 31 deletions

diff --git a/lib/Target/Mips/Mips64InstrInfo.td b/lib/Target/Mips/Mips64InstrInfo.td
index 56d2b42..1a57756 100644
--- a/lib/Target/Mips/Mips64InstrInfo.td
+++ b/lib/Target/Mips/Mips64InstrInfo.td
@@ -31,19 +31,6 @@ def Subtract32 : SDNodeXForm<imm, [{
 // shamt must fit in 6 bits.
 def immZExt6 : ImmLeaf<i32, [{return Imm == (Imm & 0x3f);}]>;
 
-// Is a 32-bit int.
-def immSExt32 : ImmLeaf<i64, [{return isInt<32>(Imm);}]>;
-
-// Transformation Function - get the higher 16 bits.
-def HIGHER : SDNodeXForm<imm, [{
-  return getImm(N, (N->getZExtValue() >> 32) & 0xFFFF);
-}]>;
-
-// Transformation Function - get the highest 16 bits.
-def HIGHEST : SDNodeXForm<imm, [{
-  return getImm(N, (N->getZExtValue() >> 48) & 0xFFFF);
-}]>;
-
 //===----------------------------------------------------------------------===//
 // Instructions specific format
 //===----------------------------------------------------------------------===//
@@ -213,24 +200,6 @@ def SLL64_64 : FR<0x0, 0x00, (outs CPU64Regs:$rd), (ins CPU64Regs:$rt),
 //  Arbitrary patterns that map to one or more instructions
 //===----------------------------------------------------------------------===//
 
-// Small immediates
-def : Pat<(i64 immSExt16:$in),
-          (DADDiu ZERO_64, imm:$in)>;
-def : Pat<(i64 immZExt16:$in),
-          (ORi64 ZERO_64, imm:$in)>;
-def : Pat<(i64 immLow16Zero:$in),
-          (LUi64 (HI16 imm:$in))>;
-
-// 32-bit immediates
-def : Pat<(i64 immSExt32:$imm),
-          (ORi64 (LUi64 (HI16 imm:$imm)), (LO16 imm:$imm))>;
-
-// Arbitrary immediates
-def : Pat<(i64 imm:$imm),
-          (ORi64 (DSLL (ORi64 (DSLL (ORi64 (LUi64 (HIGHEST imm:$imm)),
-           (HIGHER imm:$imm)), 16), (HI16 imm:$imm)), 16),
-           (LO16 imm:$imm))>;
-
 // extended loads
 let Predicates = [NotN64] in {
   def : Pat<(i64 (extloadi1  addr:$src)), (LB64 addr:$src)>;
diff --git a/lib/Target/Mips/MipsISelDAGToDAG.cpp b/lib/Target/Mips/MipsISelDAGToDAG.cpp
index 0194ed5..bdb7ca4 100644
--- a/lib/Target/Mips/MipsISelDAGToDAG.cpp
+++ b/lib/Target/Mips/MipsISelDAGToDAG.cpp
@@ -13,6 +13,7 @@
 
 #define DEBUG_TYPE "mips-isel"
 #include "Mips.h"
+#include "MipsAnalyzeImmediate.h"
 #include "MipsMachineFunction.h"
 #include "MipsRegisterInfo.h"
 #include "MipsSubtarget.h"
@@ -317,6 +318,47 @@ SDNode* MipsDAGToDAGISel::Select(SDNode *Node) {
     break;
   }
 
+  case ISD::Constant: {
+    const ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Node);
+    unsigned Size = CN->getValueSizeInBits(0);
+
+    if (Size == 32)
+      break;
+
+    MipsAnalyzeImmediate AnalyzeImm;
+    int64_t Imm = CN->getSExtValue();
+
+    const MipsAnalyzeImmediate::InstSeq &Seq =
+      AnalyzeImm.Analyze(Imm, Size, false);
+    
+    MipsAnalyzeImmediate::InstSeq::const_iterator Inst = Seq.begin();
+    DebugLoc DL = CN->getDebugLoc();
+    SDNode *RegOpnd;
+    SDValue ImmOpnd = CurDAG->getTargetConstant(SignExtend64<16>(Inst->ImmOpnd),
+                                                MVT::i64);
+
+    // The first instruction can be a LUi which is different from other
+    // instructions (ADDiu, ORI and SLL) in that it does not have a register
+    // operand.
+    if (Inst->Opc == Mips::LUi64)
+      RegOpnd = CurDAG->getMachineNode(Inst->Opc, DL, MVT::i64, ImmOpnd);
+    else
+      RegOpnd =
+        CurDAG->getMachineNode(Inst->Opc, DL, MVT::i64,
+                               CurDAG->getRegister(Mips::ZERO_64, MVT::i64),
+                               ImmOpnd);
+
+    // The remaining instructions in the sequence are handled here.
+    for (++Inst; Inst != Seq.end(); ++Inst) {
+      ImmOpnd = CurDAG->getTargetConstant(SignExtend64<16>(Inst->ImmOpnd),
+                                          MVT::i64);
+      RegOpnd = CurDAG->getMachineNode(Inst->Opc, DL, MVT::i64,
+                                       SDValue(RegOpnd, 0), ImmOpnd);
+    }
+
+    return RegOpnd;
+  }
+
   case MipsISD::ThreadPointer: {
     EVT PtrVT = TLI.getPointerTy();
     unsigned RdhwrOpc, SrcReg, DestReg;