[SelectionDAG][Mips][Sparc] Don't allow SimplifyDemandedBits to constant fold TargetConstant nodes to a Constant.

Summary:
After the switch in SimplifyDemandedBits, it tries to create a
constant when possible. If the original node is a TargetConstant
the default in the switch will call computeKnownBits on the
TargetConstant which will succeed. This results in the
TargetConstant becoming a Constant. But TargetConstant exists to
avoid being changed.

I've fixed the two cases that relied on this in tree by explicitly
making the nodes constant instead of target constant. The Sparc
case is an old bug. The Mips case was recently introduced now that
ImmArg on intrinsics gets turned into a TargetConstant when the
SelectionDAG is created. I've removed the ImmArg since it lowers
to generic code.

Reviewers: arsenm, RKSimon, spatel

Subscribers: jyknight, sdardis, wdng, arichardson, hiraditya, fedor.sergeev, jrtc27, atanasyan, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67802

llvm-svn: 372409

Author: topperc

llvm/include/llvm/IR/IntrinsicsMips.td

@@ -1260,16 +1260,16 @@ def int_mips_insve_d : GCCBuiltin<"__builtin_msa_insve_d">,
 
 def int_mips_ld_b : GCCBuiltin<"__builtin_msa_ld_b">,
   Intrinsic<[llvm_v16i8_ty], [llvm_ptr_ty, llvm_i32_ty],
-  [IntrReadMem, IntrArgMemOnly, ImmArg<1>]>;
+  [IntrReadMem, IntrArgMemOnly]>;
 def int_mips_ld_h : GCCBuiltin<"__builtin_msa_ld_h">,
   Intrinsic<[llvm_v8i16_ty], [llvm_ptr_ty, llvm_i32_ty],
-  [IntrReadMem, IntrArgMemOnly, ImmArg<1>]>;
+  [IntrReadMem, IntrArgMemOnly]>;
 def int_mips_ld_w : GCCBuiltin<"__builtin_msa_ld_w">,
   Intrinsic<[llvm_v4i32_ty], [llvm_ptr_ty, llvm_i32_ty],
-  [IntrReadMem, IntrArgMemOnly, ImmArg<1>]>;
+  [IntrReadMem, IntrArgMemOnly]>;
 def int_mips_ld_d : GCCBuiltin<"__builtin_msa_ld_d">,
   Intrinsic<[llvm_v2i64_ty], [llvm_ptr_ty, llvm_i32_ty],
-  [IntrReadMem, IntrArgMemOnly, ImmArg<1>]>;
+  [IntrReadMem, IntrArgMemOnly]>;
 
 def int_mips_ldi_b : GCCBuiltin<"__builtin_msa_ldi_b">,
   Intrinsic<[llvm_v16i8_ty], [llvm_i32_ty], [IntrNoMem, ImmArg<0>]>;
@@ -1684,16 +1684,16 @@ def int_mips_srlri_d : GCCBuiltin<"__builtin_msa_srlri_d">,
 
 def int_mips_st_b : GCCBuiltin<"__builtin_msa_st_b">,
   Intrinsic<[], [llvm_v16i8_ty, llvm_ptr_ty, llvm_i32_ty],
-  [IntrArgMemOnly, ImmArg<2>]>;
+  [IntrArgMemOnly]>;
 def int_mips_st_h : GCCBuiltin<"__builtin_msa_st_h">,
   Intrinsic<[], [llvm_v8i16_ty, llvm_ptr_ty, llvm_i32_ty],
-  [IntrArgMemOnly, ImmArg<2>]>;
+  [IntrArgMemOnly]>;
 def int_mips_st_w : GCCBuiltin<"__builtin_msa_st_w">,
   Intrinsic<[], [llvm_v4i32_ty, llvm_ptr_ty, llvm_i32_ty],
-  [IntrArgMemOnly, ImmArg<2>]>;
+  [IntrArgMemOnly]>;
 def int_mips_st_d : GCCBuiltin<"__builtin_msa_st_d">,
   Intrinsic<[], [llvm_v2i64_ty, llvm_ptr_ty, llvm_i32_ty],
-  [IntrArgMemOnly, ImmArg<2>]>;
+  [IntrArgMemOnly]>;
 
 def int_mips_subs_s_b : GCCBuiltin<"__builtin_msa_subs_s_b">,
   Intrinsic<[llvm_v16i8_ty], [llvm_v16i8_ty, llvm_v16i8_ty], [IntrNoMem]>;

llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp

@@ -805,6 +805,8 @@ bool TargetLowering::SimplifyDemandedBits(
 
   KnownBits Known2, KnownOut;
   switch (Op.getOpcode()) {
+  case ISD::TargetConstant:
+    llvm_unreachable("Can't simplify this node");
   case ISD::SCALAR_TO_VECTOR: {
     if (!DemandedElts[0])
       return TLO.CombineTo(Op, TLO.DAG.getUNDEF(VT));

llvm/lib/Target/Sparc/SparcISelLowering.cpp

@@ -2244,7 +2244,7 @@ SDValue SparcTargetLowering::LowerF128Compare(SDValue LHS, SDValue RHS,
     return DAG.getNode(SPISD::CMPICC, DL, MVT::Glue, Result, RHS);
   }
   case SPCC::FCC_UL : {
-    SDValue Mask   = DAG.getTargetConstant(1, DL, Result.getValueType());
+    SDValue Mask   = DAG.getConstant(1, DL, Result.getValueType());
     Result = DAG.getNode(ISD::AND, DL, Result.getValueType(), Result, Mask);
     SDValue RHS    = DAG.getTargetConstant(0, DL, Result.getValueType());
     SPCC = SPCC::ICC_NE;
@@ -2277,14 +2277,14 @@ SDValue SparcTargetLowering::LowerF128Compare(SDValue LHS, SDValue RHS,
     return DAG.getNode(SPISD::CMPICC, DL, MVT::Glue, Result, RHS);
   }
   case SPCC::FCC_LG :  {
-    SDValue Mask   = DAG.getTargetConstant(3, DL, Result.getValueType());
+    SDValue Mask   = DAG.getConstant(3, DL, Result.getValueType());
     Result = DAG.getNode(ISD::AND, DL, Result.getValueType(), Result, Mask);
     SDValue RHS    = DAG.getTargetConstant(0, DL, Result.getValueType());
     SPCC = SPCC::ICC_NE;
     return DAG.getNode(SPISD::CMPICC, DL, MVT::Glue, Result, RHS);
   }
   case SPCC::FCC_UE : {
-    SDValue Mask   = DAG.getTargetConstant(3, DL, Result.getValueType());
+    SDValue Mask   = DAG.getConstant(3, DL, Result.getValueType());
     Result = DAG.getNode(ISD::AND, DL, Result.getValueType(), Result, Mask);
     SDValue RHS    = DAG.getTargetConstant(0, DL, Result.getValueType());
     SPCC = SPCC::ICC_E;