From 2946549a2817681f9117662139cc0f2241939965 Mon Sep 17 00:00:00 2001
From: Jush Lu <jush.msn@gmail.com>
Date: Fri, 3 Aug 2012 02:37:48 +0000
Subject: [PATCH] [arm-fast-isel] Add support for shl, lshr, and ashr.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161230 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMFastISel.cpp        | 62 +++++++++++++++++++++++++++++++++++
 test/CodeGen/ARM/fast-isel-shifter.ll | 50 ++++++++++++++++++++++++++++
 2 files changed, 112 insertions(+)
 create mode 100644 test/CodeGen/ARM/fast-isel-shifter.ll

diff --git a/lib/Target/ARM/ARMFastISel.cpp b/lib/Target/ARM/ARMFastISel.cpp
index ca8ffea9fc0..29f90b768ee 100644
--- a/lib/Target/ARM/ARMFastISel.cpp
+++ b/lib/Target/ARM/ARMFastISel.cpp
@@ -167,6 +167,7 @@ class ARMFastISel : public FastISel {
     bool SelectRet(const Instruction *I);
     bool SelectTrunc(const Instruction *I);
     bool SelectIntExt(const Instruction *I);
+    bool SelectShift(const Instruction *I, ARM_AM::ShiftOpc ShiftTy);
 
     // Utility routines.
   private:
@@ -2613,6 +2614,61 @@ bool ARMFastISel::SelectIntExt(const Instruction *I) {
   return true;
 }
 
+bool ARMFastISel::SelectShift(const Instruction *I,
+                              ARM_AM::ShiftOpc ShiftTy) {
+  // We handle thumb2 mode by target independent selector
+  // or SelectionDAG ISel.
+  if (isThumb2)
+    return false;
+
+  // Only handle i32 now.
+  EVT DestVT = TLI.getValueType(I->getType(), true);
+  if (DestVT != MVT::i32)
+    return false;
+
+  unsigned Opc = ARM::MOVsr;
+  unsigned ShiftImm;
+  Value *Src2Value = I->getOperand(1);
+  if (const ConstantInt *CI = dyn_cast<ConstantInt>(Src2Value)) {
+    ShiftImm = CI->getZExtValue();
+
+    // Fall back to selection DAG isel if the shift amount
+    // is zero or greater than the width of the value type.
+    if (ShiftImm == 0 || ShiftImm >=32)
+      return false;
+
+    Opc = ARM::MOVsi;
+  }
+
+  Value *Src1Value = I->getOperand(0);
+  unsigned Reg1 = getRegForValue(Src1Value);
+  if (Reg1 == 0) return false;
+
+  unsigned Reg2;
+  if (Opc == ARM::MOVsr) {
+    Reg2 = getRegForValue(Src2Value);
+    if (Reg2 == 0) return false;
+  }
+
+  unsigned ResultReg = createResultReg(TLI.getRegClassFor(MVT::i32));
+  if(ResultReg == 0) return false;
+
+  MachineInstrBuilder MIB = BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+                                    TII.get(Opc), ResultReg)
+                            .addReg(Reg1);
+
+  if (Opc == ARM::MOVsi)
+    MIB.addImm(ARM_AM::getSORegOpc(ShiftTy, ShiftImm));
+  else if (Opc == ARM::MOVsr) {
+    MIB.addReg(Reg2);
+    MIB.addImm(ARM_AM::getSORegOpc(ShiftTy, 0));
+  }
+
+  AddOptionalDefs(MIB);
+  UpdateValueMap(I, ResultReg);
+  return true;
+}
+
 // TODO: SoftFP support.
 bool ARMFastISel::TargetSelectInstruction(const Instruction *I) {
 
@@ -2673,6 +2729,12 @@ bool ARMFastISel::TargetSelectInstruction(const Instruction *I) {
     case Instruction::ZExt:
     case Instruction::SExt:
       return SelectIntExt(I);
+    case Instruction::Shl:
+      return SelectShift(I, ARM_AM::lsl);
+    case Instruction::LShr:
+      return SelectShift(I, ARM_AM::lsr);
+    case Instruction::AShr:
+      return SelectShift(I, ARM_AM::asr);
     default: break;
   }
   return false;
diff --git a/test/CodeGen/ARM/fast-isel-shifter.ll b/test/CodeGen/ARM/fast-isel-shifter.ll
new file mode 100644
index 00000000000..111818b289e
--- /dev/null
+++ b/test/CodeGen/ARM/fast-isel-shifter.ll
@@ -0,0 +1,50 @@
+; RUN: llc < %s -O0 -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=armv7-apple-ios | FileCheck %s --check-prefix=ARM
+
+define i32 @shl() nounwind ssp {
+entry:
+; ARM: shl
+; ARM: lsl r0, r0, #2
+  %shl = shl i32 -1, 2
+  ret i32 %shl
+}
+
+define i32 @shl_reg(i32 %src1, i32 %src2) nounwind ssp {
+entry:
+; ARM: shl_reg
+; ARM: lsl r0, r0, r1
+  %shl = shl i32 %src1, %src2
+  ret i32 %shl
+}
+
+define i32 @lshr() nounwind ssp {
+entry:
+; ARM: lshr
+; ARM: lsr r0, r0, #2
+  %lshr = lshr i32 -1, 2
+  ret i32 %lshr
+}
+
+define i32 @lshr_reg(i32 %src1, i32 %src2) nounwind ssp {
+entry:
+; ARM: lshr_reg
+; ARM: lsr r0, r0, r1
+  %lshr = lshr i32 %src1, %src2
+  ret i32 %lshr
+}
+
+define i32 @ashr() nounwind ssp {
+entry:
+; ARM: ashr
+; ARM: asr r0, r0, #2
+  %ashr = ashr i32 -1, 2
+  ret i32 %ashr
+}
+
+define i32 @ashr_reg(i32 %src1, i32 %src2) nounwind ssp {
+entry:
+; ARM: ashr_reg
+; ARM: asr r0, r0, r1
+  %ashr = ashr i32 %src1, %src2
+  ret i32 %ashr
+}
+
-- 
2.11.0