Reviewers: dcarney,
Message:
PTAL
Description:
Ensure we don't underflow in BCE
BUG=469148
LOG=y
Please review this at https://codereview.chromium.org/1023123003/
Base URL: https://chromium.googlesource.com/v8/v8.git@master
Affected files (+37, -1 lines):
M src/hydrogen-bce.cc
A test/mjsunit/regress/regress-bce-underflow.js
Index: src/hydrogen-bce.cc
diff --git a/src/hydrogen-bce.cc b/src/hydrogen-bce.cc
index
18bd0affb6ee2d2ba7a29e6000f576cc23352784..3bf8e9f03904c76ca9ee406cf5a4dbfed517148b
100644
--- a/src/hydrogen-bce.cc
+++ b/src/hydrogen-bce.cc
@@ -56,7 +56,8 @@ class BoundsCheckKey : public ZoneObject {
constant = HConstant::cast(check->index());
}
- if (constant != NULL && constant->HasInteger32Value()) {
+ if (constant != NULL && constant->HasInteger32Value() &&
+ constant->Integer32Value() != kMinInt) {
*offset = is_sub ? - constant->Integer32Value()
: constant->Integer32Value();
} else {
Index: test/mjsunit/regress/regress-bce-underflow.js
diff --git a/test/mjsunit/regress/regress-bce-underflow.js
b/test/mjsunit/regress/regress-bce-underflow.js
new file mode 100644
index
0000000000000000000000000000000000000000..daa776005e7b5bcb165cd04f2c6abf226fc720b3
--- /dev/null
+++ b/test/mjsunit/regress/regress-bce-underflow.js
@@ -0,0 +1,35 @@
+// Copyright 2015 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 f(a, i, bool) {
+ var result;
+ if (bool) {
+ // Make sure i - -0x80000000 doesn't overflow in BCE, missing a check
for
+ // x-0 later on.
+ result = f2(a, 0x7fffffff, i, i, -0x80000000);
+ } else {
+ result = f2(a, -3, 4, i, 0);
+ }
+ return result;
+}
+
+function f2(a, c, x, i, d) {
+ return a[x + c] + a[x - 0] + a[i - d];
+}
+
+
+var a = [];
+var i = 0;
+a.push(i++);
+a.push(i++);
+a.push(i++);
+a.push(i++);
+a.push(i++);
+f(a, 0, false);
+f(a, 0, false);
+f(a, 0, false);
+%OptimizeFunctionOnNextCall(f);
+%DebugPrint(f(a, -0x7fffffff, true));
--
--
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