Fix arm64 bug in 31bit Smis

Change-Id: Id73e9e4862d3b7751b6867183a43cfa7a0cdef52
Bug: v8:8344
Reviewed-on: https://chromium-review.googlesource.com/c/1355145
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57966}

include/v8-internal.h

@@ -86,11 +86,14 @@ struct SmiTagging<8> {
   }
 };
 
-#if defined(V8_COMPRESS_POINTERS) || defined(V8_31BIT_SMIS_ON_64BIT_ARCH)
+#if defined(V8_COMPRESS_POINTERS)
 static_assert(
     kApiSystemPointerSize == kApiInt64Size,
     "Pointer compression can be enabled only for 64-bit architectures");
-typedef SmiTagging<4> PlatformSmiTagging;
+#endif
+
+#if defined(V8_COMPRESS_POINTERS) || defined(V8_31BIT_SMIS_ON_64BIT_ARCH)
+typedef SmiTagging<kApiIntSize> PlatformSmiTagging;
 #else
 typedef SmiTagging<kApiSystemPointerSize> PlatformSmiTagging;
 #endif

src/compiler/effect-control-linearizer.cc

@@ -3926,6 +3926,9 @@ Node* EffectControlLinearizer::SmiMaxValueConstant() {
 }
 
 Node* EffectControlLinearizer::SmiShiftBitsConstant() {
+  if (machine()->Is64() && SmiValuesAre31Bits()) {
+    return __ Int32Constant(kSmiShiftSize + kSmiTagSize);
+  }
   return __ IntPtrConstant(kSmiShiftSize + kSmiTagSize);
 }