Subzero, MIPS32: Intrinsic call Ctlz for i32

src/IceTargetLoweringMIPS32.cpp

 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 /// \brief Implements the TargetLoweringMIPS32 class, which consists almost
@@ skipping 2828 matching lines @@
   }
   case Intrinsics::Bswap: {
     UnimplementedLoweringError(this, Instr);
     return;
   }
   case Intrinsics::Ctpop: {
     llvm::report_fatal_error("Ctpop should have been prelowered.");
     return;
   }
   case Intrinsics::Ctlz: {
-    UnimplementedLoweringError(this, Instr);
-    return;
+    auto *Src = Instr->getArg(0);
+    const Type SrcTy = Src->getType();

[Jim Stichnoth, 2016/09/22 18:18:24]

This gives an error in a MINIMAL build (make -f Makefile.standalone MINIMAL=1)
because SrcTy is only used inside an assert.

That said, I think the assert should just be removed because it is handled more
strongly in the "default:" case below.

[obucinac, 2016/09/22 18:58:16]

Maybe this would do...

+    assert(SrcTy == IceType_i32 || SrcTy == IceType_i64);
+    switch (Src->getType()) {
+    case IceType_i32: {
+      auto *T = I32Reg();
+      auto *SrcR = legalizeToReg(Src);
+      _clz(T, SrcR);
+      _mov(Dest, T);
+      break;
+    }
+    case IceType_i64: {
+      UnimplementedLoweringError(this, Instr);
+      break;
+    }
+    default:
+      llvm::report_fatal_error("Control flow should never have reached here.");
+    }
+    break;
   }
   case Intrinsics::Cttz: {
     UnimplementedLoweringError(this, Instr);
     return;
   }
   case Intrinsics::Fabs: {
     if (isScalarFloatingType(DestTy)) {
       Variable *T = makeReg(DestTy);
       if (DestTy == IceType_f32) {
         _abs_s(T, legalizeToReg(Instr->getArg(0)));
@@ skipping 880 matching lines @@
   Str << "\t.set\t"
       << "nomips16\n";
 }
 
 SmallBitVector TargetMIPS32::TypeToRegisterSet[RCMIPS32_NUM];
 SmallBitVector TargetMIPS32::TypeToRegisterSetUnfiltered[RCMIPS32_NUM];
 SmallBitVector TargetMIPS32::RegisterAliases[RegMIPS32::Reg_NUM];
 
 } // end of namespace MIPS32
 } // end of namespace Ice