deps: V8: cherry-pick c449afa1953b

Original commit message:

    Merged: [compiler] Fix a bug in SimplifiedLowering

    Revision: ba1b2cc09ab98b51ca3828d29d19ae3b0a7c3a92

    BUG=chromium:1150649
    NOTRY=true
    NOPRESUBMIT=true
    NOTREECHECKS=true

    (cherry picked from commit 966d0eb98dd2630e861d267288fa2c63be9b5465)

    Change-Id: Ic903e61ee00b7c240bed96633d1eab582c295308
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2557985
    Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
    Commit-Queue: Georg Neis <neis@chromium.org>
    Cr-Original-Commit-Position: refs/branch-heads/8.8@{#10}
    Cr-Original-Branched-From: 2dbcdc105b963ee2501c82139eef7e0603977ff0-refs/heads/8.8.278@{#1}
    Cr-Original-Branched-From: 366d30c99049b3f1c673f8a93deb9f879d0fa9f0-refs/heads/master@{#71094}
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2624749
    Reviewed-by: Jana Grill <janagrill@chromium.org>
    Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
    Commit-Queue: Victor-Gabriel Savu <vsavu@google.com>
    Cr-Commit-Position: refs/branch-heads/8.6@{#52}
    Cr-Branched-From: a64aed2333abf49e494d2a5ce24bbd14fff19f60-refs/heads/8.6.395@{#1}
    Cr-Branched-From: a626bc036236c9bf92ac7b87dc40c9e538b087e3-refs/heads/master@{#69472}

Refs: https://github.com/v8/v8/commit/c449afa1953b5bbb68c48818433a587578d79a9b

PR-URL: https://github.com/nodejs/node/pull/38275
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Shelley Vohr <codebytere@gmail.com>

2 files changed, 34 insertions, 3 deletions

diff --git a/deps/v8/src/compiler/simplified-lowering.cc b/deps/v8/src/compiler/simplified-lowering.cc
index 9252906e70d..a9229617dad 100644
--- a/deps/v8/src/compiler/simplified-lowering.cc
+++ b/deps/v8/src/compiler/simplified-lowering.cc
@@ -1381,7 +1381,6 @@ class RepresentationSelector {
                 IsSomePositiveOrderedNumber(input1_type)
             ? CheckForMinusZeroMode::kDontCheckForMinusZero
             : CheckForMinusZeroMode::kCheckForMinusZero;
-
     NodeProperties::ChangeOp(node, simplified()->CheckedInt32Mul(mz_mode));
   }
 
@@ -1425,6 +1424,13 @@ class RepresentationSelector {
 
     Type left_feedback_type = TypeOf(node->InputAt(0));
     Type right_feedback_type = TypeOf(node->InputAt(1));
+
+    // Using Signed32 as restriction type amounts to promising there won't be
+    // signed overflow. This is incompatible with relying on a Word32
+    // truncation in order to skip the overflow check.
+    Type const restriction =
+        truncation.IsUsedAsWord32() ? Type::Any() : Type::Signed32();
+
     // Handle the case when no int32 checks on inputs are necessary (but
     // an overflow check is needed on the output). Note that we do not
     // have to do any check if at most one side can be minus zero. For
@@ -1438,7 +1444,7 @@ class RepresentationSelector {
         right_upper.Is(Type::Signed32OrMinusZero()) &&
         (left_upper.Is(Type::Signed32()) || right_upper.Is(Type::Signed32()))) {
       VisitBinop<T>(node, UseInfo::TruncatingWord32(),
-                    MachineRepresentation::kWord32, Type::Signed32());
+                    MachineRepresentation::kWord32, restriction);
     } else {
       // If the output's truncation is identify-zeros, we can pass it
       // along. Moreover, if the operation is addition and we know the
@@ -1458,8 +1464,9 @@ class RepresentationSelector {
       UseInfo right_use = CheckedUseInfoAsWord32FromHint(hint, FeedbackSource(),
                                                          kIdentifyZeros);
       VisitBinop<T>(node, left_use, right_use, MachineRepresentation::kWord32,
-                    Type::Signed32());
+                    restriction);
     }
+
     if (lower<T>()) {
       if (truncation.IsUsedAsWord32() ||
           !CanOverflowSigned32(node->op(), left_feedback_type,
diff --git a/deps/v8/test/mjsunit/compiler/regress-1150649.js b/deps/v8/test/mjsunit/compiler/regress-1150649.js
new file mode 100644
index 00000000000..a193481a3a2
--- /dev/null
+++ b/deps/v8/test/mjsunit/compiler/regress-1150649.js
@@ -0,0 +1,24 @@
+// Copyright 2020 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 foo(a) {
+  var y = 0x7fffffff;  // 2^31 - 1
+
+  // Widen the static type of y (this condition never holds).
+  if (a == NaN) y = NaN;
+
+  // The next condition holds only in the warmup run. It leads to Smi
+  // (SignedSmall) feedback being collected for the addition below.
+  if (a) y = -1;
+
+  const z = (y + 1)|0;
+  return z < 0;
+}
+
+%PrepareFunctionForOptimization(foo);
+assertFalse(foo(true));
+%OptimizeFunctionOnNextCall(foo);
+assertTrue(foo(false));