Reviewers: rossberg,
Message:
PTAL.
Description:
Fix and cleanup can_be_minus_zero computation
Please review this at https://codereview.chromium.org/18434004/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/hydrogen-instructions.cc
A + test/mjsunit/compiler/minus-zero.js
Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index
932fd47af13fc12bf081f3bb232063edd59ee7d2..b3266cfd768aba039c109726ca5018ee7b33cb46
100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -1736,9 +1736,10 @@ Range* HValue::InferRange(Zone* zone) {
result = new(zone) Range(Smi::kMinValue, Smi::kMaxValue);
result->set_can_be_minus_zero(false);
} else {
- // Untagged integer32 cannot be -0, all other representations can.
result = new(zone) Range();
- result->set_can_be_minus_zero(!representation().IsInteger32());
+ result->set_can_be_minus_zero(!CheckFlag(kAllUsesTruncatingToInt32));
+ // TODO(jkummerow): The range cannot be minus zero when the upper type
+ // bound is Integer32.
}
return result;
}
@@ -1756,7 +1757,8 @@ Range* HChange::InferRange(Zone* zone) {
Range* result = (input_range != NULL)
? input_range->Copy(zone)
: HValue::InferRange(zone);
- if (to().IsInteger32()) result->set_can_be_minus_zero(false);
+ result->set_can_be_minus_zero(!to().IsSmiOrInteger32() ||
+ !CheckFlag(kAllUsesTruncatingToInt32));
return result;
}
@@ -1801,9 +1803,9 @@ Range* HAdd::InferRange(Zone* zone) {
CheckFlag(kAllUsesTruncatingToInt32)) {
ClearFlag(kCanOverflow);
}
- if (!CheckFlag(kAllUsesTruncatingToInt32)) {
- res->set_can_be_minus_zero(a->CanBeMinusZero() &&
b->CanBeMinusZero());
- }
+ res->set_can_be_minus_zero(!CheckFlag(kAllUsesTruncatingToInt32) &&
+ a->CanBeMinusZero() &&
+ b->CanBeMinusZero());
return res;
} else {
return HValue::InferRange(zone);
@@ -1820,9 +1822,9 @@ Range* HSub::InferRange(Zone* zone) {
CheckFlag(kAllUsesTruncatingToInt32)) {
ClearFlag(kCanOverflow);
}
- if (!CheckFlag(kAllUsesTruncatingToInt32)) {
- res->set_can_be_minus_zero(a->CanBeMinusZero() && b->CanBeZero());
- }
+ res->set_can_be_minus_zero(!CheckFlag(kAllUsesTruncatingToInt32) &&
+ a->CanBeMinusZero() &&
+ b->CanBeZero());
return res;
} else {
return HValue::InferRange(zone);
@@ -1841,11 +1843,9 @@ Range* HMul::InferRange(Zone* zone) {
// precise and therefore not the same as converting to Double and
back.
ClearFlag(kCanOverflow);
}
- if (!CheckFlag(kAllUsesTruncatingToInt32)) {
- bool m0 = (a->CanBeZero() && b->CanBeNegative()) ||
- (a->CanBeNegative() && b->CanBeZero());
- res->set_can_be_minus_zero(m0);
- }
+ res->set_can_be_minus_zero(!CheckFlag(kAllUsesTruncatingToInt32) &&
+ ((a->CanBeZero() && b->CanBeNegative()) ||
+ (a->CanBeNegative() && b->CanBeZero())));
return res;
} else {
return HValue::InferRange(zone);
@@ -1858,16 +1858,9 @@ Range* HDiv::InferRange(Zone* zone) {
Range* a = left()->range();
Range* b = right()->range();
Range* result = new(zone) Range();
- if (!CheckFlag(kAllUsesTruncatingToInt32)) {
- if (a->CanBeMinusZero()) {
- result->set_can_be_minus_zero(true);
- }
-
- if (a->CanBeZero() && b->CanBeNegative()) {
- result->set_can_be_minus_zero(true);
- }
- }
-
+ result->set_can_be_minus_zero(!CheckFlag(kAllUsesTruncatingToInt32) &&
+ (a->CanBeMinusZero() ||
+ (a->CanBeZero() &&
b->CanBeNegative())));
if (!a->Includes(kMinInt) || !b->Includes(-1)) {
ClearFlag(HValue::kCanOverflow);
}
@@ -1897,9 +1890,8 @@ Range* HMod::InferRange(Zone* zone) {
Range* result = new(zone) Range(left_can_be_negative ?
-positive_bound : 0,
a->CanBePositive() ? positive_bound :
0);
- if (left_can_be_negative && !CheckFlag(kAllUsesTruncatingToInt32)) {
- result->set_can_be_minus_zero(true);
- }
+ result->set_can_be_minus_zero(!CheckFlag(kAllUsesTruncatingToInt32) &&
+ left_can_be_negative);
if (!a->Includes(kMinInt) || !b->Includes(-1)) {
ClearFlag(HValue::kCanOverflow);
@@ -2432,7 +2424,9 @@ Range* HBitwise::InferRange(Zone* zone) {
? static_cast<int32_t>(-limit) : 0;
return new(zone) Range(min, static_cast<int32_t>(limit - 1));
}
- return HValue::InferRange(zone);
+ Range* result = HValue::InferRange(zone);
+ result->set_can_be_minus_zero(false);
+ return result;
}
const int32_t kDefaultMask = static_cast<int32_t>(0xffffffff);
int32_t left_mask = (left()->range() != NULL)
@@ -2444,9 +2438,11 @@ Range* HBitwise::InferRange(Zone* zone) {
int32_t result_mask = (op() == Token::BIT_AND)
? left_mask & right_mask
: left_mask | right_mask;
- return (result_mask >= 0)
- ? new(zone) Range(0, result_mask)
- : HValue::InferRange(zone);
+ if (result_mask >= 0) return new(zone) Range(0, result_mask);
+
+ Range* result = HValue::InferRange(zone);
+ result->set_can_be_minus_zero(false);
+ return result;
}
@@ -2458,7 +2454,6 @@ Range* HSar::InferRange(Zone* zone) {
? left()->range()->Copy(zone)
: new(zone) Range();
result->Sar(c->Integer32Value());
- result->set_can_be_minus_zero(false);
return result;
}
}
@@ -2483,7 +2478,6 @@ Range* HShr::InferRange(Zone* zone) {
? left()->range()->Copy(zone)
: new(zone) Range();
result->Sar(c->Integer32Value());
- result->set_can_be_minus_zero(false);
return result;
}
}
@@ -2500,7 +2494,6 @@ Range* HShl::InferRange(Zone* zone) {
? left()->range()->Copy(zone)
: new(zone) Range();
result->Shl(c->Integer32Value());
- result->set_can_be_minus_zero(false);
return result;
}
}
Index: test/mjsunit/compiler/minus-zero.js
diff --git a/test/mjsunit/regress/regress-crbug-173974.js
b/test/mjsunit/compiler/minus-zero.js
similarity index 91%
copy from test/mjsunit/regress/regress-crbug-173974.js
copy to test/mjsunit/compiler/minus-zero.js
index
905bd6058a0ad0fe2ebe10e4c7dafbe9945cbe3b..6efceb54e36834c217732a7974f0c5d2a2cca132
100644
--- a/test/mjsunit/regress/regress-crbug-173974.js
+++ b/test/mjsunit/compiler/minus-zero.js
@@ -27,10 +27,11 @@
// Flags: --allow-natives-syntax
-function f() {
- var count = "";
- count[0] --;
+function add(x, y) {
+ return x + y;
}
-f();
-%OptimizeFunctionOnNextCall(f);
-f();
+
+assertEquals(0, add(0, 0));
+assertEquals(0, add(0, 0));
+%OptimizeFunctionOnNextCall(add);
+assertEquals(-0, add(-0, -0));
--
--
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