[arm64] Fix another ubfx corner case.

This issue was fixed in VisitWord64And in 2f8ad11f. Port the fix to
VisitWord32And.

BUG=

Review-Url: https://codereview.chromium.org/2815853002
Cr-Commit-Position: refs/heads/master@{#44636}

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

@@ -919,7 +919,8 @@ void InstructionSelector::VisitWord32And(Node* node) {
     uint32_t mask = m.right().Value();
     uint32_t mask_width = base::bits::CountPopulation32(mask);
     uint32_t mask_msb = base::bits::CountLeadingZeros32(mask);
-    if ((mask_width != 0) && (mask_msb + mask_width == 32)) {
+    if ((mask_width != 0) && (mask_width != 32) &&
+        (mask_msb + mask_width == 32)) {
       // The mask must be contiguous, and occupy the least-significant bits.
       DCHECK_EQ(0u, base::bits::CountTrailingZeros32(mask));
 

test/cctest/compiler/test-run-machops.cc

@@ -6778,6 +6778,14 @@ TEST(Regression6028) {
   CHECK_EQ(1, m.Call());
 }
 
+TEST(Regression5951_32bit) {
+  BufferedRawMachineAssemblerTester<int32_t> m(MachineType::Int32());
+  m.Return(m.Word32And(m.Word32Shr(m.Parameter(0), m.Int32Constant(0)),
+                       m.Int32Constant(0xffffffff)));
+  int32_t input = 1234;
+  CHECK_EQ(input, m.Call(input));
+}
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8