[X86] Remove fast-isel code for handling i8 shifts. This is handled by auto generated code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316797 91177308-0d34-0410-b5e6-96231b3b80d8

Author: topperc

lib/Target/X86/X86FastISel.cpp

@@ -1785,16 +1785,9 @@ bool X86FastISel::X86SelectBranch(const Instruction *I) {
 bool X86FastISel::X86SelectShift(const Instruction *I) {
   unsigned CReg = 0, OpReg = 0;
   const TargetRegisterClass *RC = nullptr;
-  if (I->getType()->isIntegerTy(8)) {
-    CReg = X86::CL;
-    RC = &X86::GR8RegClass;
-    switch (I->getOpcode()) {
-    case Instruction::LShr: OpReg = X86::SHR8rCL; break;
-    case Instruction::AShr: OpReg = X86::SAR8rCL; break;
-    case Instruction::Shl:  OpReg = X86::SHL8rCL; break;
-    default: return false;
-    }
-  } else if (I->getType()->isIntegerTy(16)) {
+  assert(!I->getType()->isIntegerTy(8) &&
+         "i8 shifts should be handled by autogenerated table");
+  if (I->getType()->isIntegerTy(16)) {
     CReg = X86::CX;
     RC = &X86::GR16RegClass;
     switch (I->getOpcode()) {
@@ -1839,10 +1832,10 @@ bool X86FastISel::X86SelectShift(const Instruction *I) {
 
   // The shift instruction uses X86::CL. If we defined a super-register
   // of X86::CL, emit a subreg KILL to precisely describe what we're doing here.
-  if (CReg != X86::CL)
-    BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
-            TII.get(TargetOpcode::KILL), X86::CL)
-      .addReg(CReg, RegState::Kill);
+  assert(CReg != X86::CL && "CReg should be a super register of CL");
+  BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
+          TII.get(TargetOpcode::KILL), X86::CL)
+    .addReg(CReg, RegState::Kill);
 
   unsigned ResultReg = createResultReg(RC);
   BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(OpReg), ResultReg)