[arm64][turbofan] Fix add+shr for big shift values.

src/compiler/arm64/instruction-selector-arm64.cc

Index: src/compiler/arm64/instruction-selector-arm64.cc
diff --git a/src/compiler/arm64/instruction-selector-arm64.cc b/src/compiler/arm64/instruction-selector-arm64.cc
index 8518b014eb0933e1fadcf72b20c411fcf6b29b4a..dc5d39ad5c70ec0e3a14ed149105767275243ae9 100644
--- a/src/compiler/arm64/instruction-selector-arm64.cc
+++ b/src/compiler/arm64/instruction-selector-arm64.cc
@@ -436,14 +436,16 @@ void VisitBinop(InstructionSelector* selector, Node* node,
     Matcher m_shift(right_node);
     inputs[input_count++] = g.UseRegisterOrImmediateZero(left_node);
     inputs[input_count++] = g.UseRegister(m_shift.left().node());
-    inputs[input_count++] = g.UseImmediate(m_shift.right().node());
+    inputs[input_count++] =
+        g.UseImmediate(static_cast<int>(m_shift.right().Value()));

[martyn.capewell, 2017/02/03 11:44:37]

I think this cast is implementation defined; the input is out of range of the
int, as that's the problem you're trying to solve. If we can assume the shift is
positive, a uint32_t cast would work.

[ahaas, 2017/02/03 12:46:11]

Thanks. a uint32_t cast would not help either because g.UseImmediate takes an
int parameter. I apply a bit mask now to make sure that the input value is
within int range. This is possible because shift is restricted to 6 bits
anyways.

   } else if (can_commute && TryMatchAnyShift(selector, node, left_node, &opcode,
                                              !is_add_sub)) {
     if (must_commute_cond) cont->Commute();
     Matcher m_shift(left_node);
     inputs[input_count++] = g.UseRegisterOrImmediateZero(right_node);
     inputs[input_count++] = g.UseRegister(m_shift.left().node());
-    inputs[input_count++] = g.UseImmediate(m_shift.right().node());
+    inputs[input_count++] =
+        g.UseImmediate(static_cast<int>(m_shift.right().Value()));
   } else {
     inputs[input_count++] = g.UseRegisterOrImmediateZero(left_node);
     inputs[input_count++] = g.UseRegister(right_node);