[ARM] Assert that ARMDAGToDAGISel creates valid UBFX/SBFX nodes.

We don't ever check these again (unless you're using
-fno-integrated-as), so make sure the extracted bits are well-defined.

I don't think it's possible to trigger any of the assertions on trunk,
but it's difficult to prove.  (The first one depends on DAGCombine to
minimize the number of set bits in AND masks; I think the others are
mathematically impossible to hit.)

llvm-svn: 335931

diff --git a/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp b/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
index b5eb57c..081d4ff 100644 (file)
--- a/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
+++ b/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
@@ -2337,6 +2337,7 @@ bool ARMDAGToDAGISel::tryV6T2BitfieldExtractOp(SDNode *N, bool isSigned) {
           return true;
         }
 
+        assert(LSB + Width + 1 <= 32 && "Shouldn't create an invalid ubfx");
         SDValue Ops[] = { N->getOperand(0).getOperand(0),
                           CurDAG->getTargetConstant(LSB, dl, MVT::i32),
                           CurDAG->getTargetConstant(Width, dl, MVT::i32),
@@ -2361,6 +2362,7 @@ bool ARMDAGToDAGISel::tryV6T2BitfieldExtractOp(SDNode *N, bool isSigned) {
       if (LSB < 0)
         return false;
       SDValue Reg0 = CurDAG->getRegister(0, MVT::i32);
+      assert(LSB + Width + 1 <= 32 && "Shouldn't create an invalid ubfx");
       SDValue Ops[] = { N->getOperand(0).getOperand(0),
                         CurDAG->getTargetConstant(LSB, dl, MVT::i32),
                         CurDAG->getTargetConstant(Width, dl, MVT::i32),
@@ -2382,6 +2384,7 @@ bool ARMDAGToDAGISel::tryV6T2BitfieldExtractOp(SDNode *N, bool isSigned) {
       // Note: The width operand is encoded as width-1.
       unsigned Width = MSB - LSB;
       SDValue Reg0 = CurDAG->getRegister(0, MVT::i32);
+      assert(Srl_imm + Width + 1 <= 32 && "Shouldn't create an invalid ubfx");
       SDValue Ops[] = { N->getOperand(0).getOperand(0),
                         CurDAG->getTargetConstant(Srl_imm, dl, MVT::i32),
                         CurDAG->getTargetConstant(Width, dl, MVT::i32),
@@ -2402,6 +2405,7 @@ bool ARMDAGToDAGISel::tryV6T2BitfieldExtractOp(SDNode *N, bool isSigned) {
       return false;
 
     SDValue Reg0 = CurDAG->getRegister(0, MVT::i32);
+    assert(LSB + Width <= 32 && "Shouldn't create an invalid ubfx");
     SDValue Ops[] = { N->getOperand(0).getOperand(0),
                       CurDAG->getTargetConstant(LSB, dl, MVT::i32),
                       CurDAG->getTargetConstant(Width - 1, dl, MVT::i32),