[LTS-M86][compiler][x64] Fix bug in InstructionSelector::ChangeInt32ToInt64

GeorgNeis · Commit Bot · commit 3066b7b2fcb3 · 2021-04-13T16:32:17.000Z
(cherry picked from commit 02f84c7) No-Try: true No-Presubmit: true No-Tree-Checks: true Bug: chromium:1196683 Change-Id: Ib4ea738b47b64edc81450583be4c80a41698c3d1 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2820971 Commit-Queue: Georg Neis <neis@chromium.org> Reviewed-by: Nico Hartmann <nicohartmann@chromium.org> Cr-Original-Commit-Position: refs/heads/master@{#73903} Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2821959 Commit-Queue: Jana Grill <janagrill@chromium.org> Reviewed-by: Georg Neis <neis@chromium.org> Reviewed-by: Victor-Gabriel Savu <vsavu@google.com> Cr-Commit-Position: refs/branch-heads/8.6@{#75} Cr-Branched-From: a64aed2-refs/heads/8.6.395@{#1} Cr-Branched-From: a626bc0-refs/heads/master@{#69472}
diff --git a/src/compiler/backend/x64/instruction-selector-x64.cc b/src/compiler/backend/x64/instruction-selector-x64.cc
@@ -1279,7 +1279,9 @@ void InstructionSelector::VisitChangeInt32ToInt64(Node* node) {
         opcode = load_rep.IsSigned() ? kX64Movsxwq : kX64Movzxwq;
         break;
       case MachineRepresentation::kWord32:
-        opcode = load_rep.IsSigned() ? kX64Movsxlq : kX64Movl;
+        // ChangeInt32ToInt64 must interpret its input as a _signed_ 32-bit
+        // integer, so here we must sign-extend the loaded value in any case.
+        opcode = kX64Movsxlq;
         break;
       default:
         UNREACHABLE();
diff --git a/test/mjsunit/compiler/regress-1196683.js b/test/mjsunit/compiler/regress-1196683.js
@@ -0,0 +1,56 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax
+
+
+(function() {
+  const arr = new Uint32Array([2**31]);
+  function foo() {
+    return (arr[0] ^ 0) + 1;
+  }
+  %PrepareFunctionForOptimization(foo);
+  assertEquals(-(2**31) + 1, foo());
+  %OptimizeFunctionOnNextCall(foo);
+  assertEquals(-(2**31) + 1, foo());
+});
+
+
+// The remaining tests already passed without the bugfix.
+
+
+(function() {
+  const arr = new Uint16Array([2**15]);
+  function foo() {
+    return (arr[0] ^ 0) + 1;
+  }
+  %PrepareFunctionForOptimization(foo);
+  assertEquals(2**15 + 1, foo());
+  %OptimizeFunctionOnNextCall(foo);
+  assertEquals(2**15 + 1, foo());
+})();
+
+
+(function() {
+  const arr = new Uint8Array([2**7]);
+  function foo() {
+    return (arr[0] ^ 0) + 1;
+  }
+  %PrepareFunctionForOptimization(foo);
+  assertEquals(2**7 + 1, foo());
+  %OptimizeFunctionOnNextCall(foo);
+  assertEquals(2**7 + 1, foo());
+})();
+
+
+(function() {
+  const arr = new Int32Array([-(2**31)]);
+  function foo() {
+    return (arr[0] >>> 0) + 1;
+  }
+  %PrepareFunctionForOptimization(foo);
+  assertEquals(2**31 + 1, foo());
+  %OptimizeFunctionOnNextCall(foo);
+  assertEquals(2**31 + 1, foo());
+})();
