AArch64: Relax assert about large shift sizes.

The reason why these large shift sizes happen is because OpaqueConstants
currently inhibit alot of DAG combining, but that has to be addressed in
another commit (like the proposal in D6946).

Differential Revision: http://reviews.llvm.org/D6940

llvm-svn: 230355

1 files changed, 9 insertions, 3 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp b/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
index ed49f6fc634..a6bac6446f2 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
@@ -1397,8 +1397,10 @@ static bool isBitfieldExtractOpFromAnd(SelectionDAG *CurDAG, SDNode *N,
   } else
     return false;
 
-  assert((BiggerPattern || (Srl_imm > 0 && Srl_imm < VT.getSizeInBits())) &&
-         "bad amount in shift node!");
+  // Bail out on large immediates. This happens when no proper
+  // combining/constant folding was performed.
+  if (!BiggerPattern && (Srl_imm <= 0 || Srl_imm >= VT.getSizeInBits()))
+    return false;
 
   LSB = Srl_imm;
   MSB = Srl_imm + (VT == MVT::i32 ? countTrailingOnes<uint32_t>(And_imm)
@@ -1502,7 +1504,11 @@ static bool isBitfieldExtractOpFromShr(SDNode *N, unsigned &Opc, SDValue &Opd0,
   } else
     return false;
 
-  assert(Shl_imm < VT.getSizeInBits() && "bad amount in shift node!");
+  // Missing combines/constant folding may have left us with strange
+  // constants.
+  if (Shl_imm >= VT.getSizeInBits())
+    return false;
+
   uint64_t Srl_imm = 0;
   if (!isIntImmediate(N->getOperand(1), Srl_imm))
     return false;