[turbofan] Reland of `Add alignment parameter to StackSlot operator`

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

Index: test/cctest/compiler/test-run-machops.cc
diff --git a/test/cctest/compiler/test-run-machops.cc b/test/cctest/compiler/test-run-machops.cc
index 2092dc9c63631b4494444263245d2db4c33f7c3b..3da6b261d781afd70d91c71e433e17fad9cd9cc5 100644
--- a/test/cctest/compiler/test-run-machops.cc
+++ b/test/cctest/compiler/test-run-machops.cc
@@ -6739,6 +6739,34 @@ TEST(ParentFramePointer) {
   CHECK_EQ(1, r.Call(1));
 }
 
+#if V8_HOST_ARCH_MIPS || V8_HOST_ARCH_MIPS64
+
+TEST(StackSlotAlignment) {
+  RawMachineAssemblerTester<int32_t> r;
+  RawMachineLabel tlabel;
+  RawMachineLabel flabel;
+  RawMachineLabel merge;
+
+  int alignments[] = {4, 8, 16};
+  int alignment_count = arraysize(alignments);
+
+  Node* alignment_counter = r.Int32Constant(0);
+  for (int i = 0; i < alignment_count; i++) {
+    for (int j = 0; j < 5; j++) {
+      Node* stack_slot =
+          r.StackSlot(MachineRepresentation::kWord32, alignments[i]);
+      alignment_counter = r.Int32Add(
+          alignment_counter,
+          r.Word32And(stack_slot, r.Int32Constant(alignments[i] - 1)));
+    }
+  }
+
+  r.Return(alignment_counter);
+  CHECK_EQ(0, r.Call(1));
+}
+
+#endif  // V8_HOST_ARCH_MIPS || V8_HOST_ARCH_MIPS64
+
 #if V8_TARGET_ARCH_64_BIT
 
 TEST(Regression5923) {