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Make sure double to int conversion is correct.

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R=svenpanne@chromium.org
BUG=v8:2260
TEST=test-utils/Utils1

Review URL: https://chromiumcodereview.appspot.com/10820047

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12216 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
yangguo@chromium.org 2012-07-30 08:34:26 +00:00
parent a448d42428
commit 0acc9e13af
4 changed files with 32 additions and 8 deletions
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12
src/conversions.h
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@ -57,13 +57,21 @@ inline double SignedZero(bool negative) {
}
// The fast double-to-(unsigned-)int conversion routine does not guarantee
// rounding towards zero.
// For NaN and values outside the int range, return INT_MIN or INT_MAX.
inline int FastD2IChecked(double x) {
if (!(x >= INT_MIN)) return INT_MIN; // Negation to catch NaNs.
if (x > INT_MAX) return INT_MAX;
return static_cast<int>(x);
}
// The fast double-to-(unsigned-)int conversion routine does not guarantee
// rounding towards zero.
// The result is unspecified if x is infinite or NaN, or if the rounded
// integer value is outside the range of type int.
inline int FastD2I(double x) {
// The static_cast convertion from double to int used to be slow, but
// as new benchmarks show, now it is much faster than lrint().
return static_cast<int>(x);
}

2
src/elements.cc
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@ -800,7 +800,7 @@ class FastElementsAccessor
}
} else {
// Otherwise, fill the unused tail with holes.
int old_length = FastD2I(array->length()->Number());
int old_length = FastD2IChecked(array->length()->Number());
for (int i = length; i < old_length; i++) {
backing_store->set_the_hole(i);
}

10
src/runtime.cc
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@ -3755,8 +3755,8 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_SubString) {
} else {
CONVERT_DOUBLE_ARG_CHECKED(from_number, 1);
CONVERT_DOUBLE_ARG_CHECKED(to_number, 2);
start = FastD2I(from_number);
end = FastD2I(to_number);
start = FastD2IChecked(from_number);
end = FastD2IChecked(to_number);
}
RUNTIME_ASSERT(end >= start);
RUNTIME_ASSERT(start >= 0);
@ -4224,7 +4224,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_NumberToFixed) {
return *isolate->factory()->infinity_symbol();
}
CONVERT_DOUBLE_ARG_CHECKED(f_number, 1);
int f = FastD2I(f_number);
int f = FastD2IChecked(f_number);
RUNTIME_ASSERT(f >= 0);
char* str = DoubleToFixedCString(value, f);
MaybeObject* res =
@ -4249,7 +4249,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_NumberToExponential) {
return *isolate->factory()->infinity_symbol();
}
CONVERT_DOUBLE_ARG_CHECKED(f_number, 1);
int f = FastD2I(f_number);
int f = FastD2IChecked(f_number);
RUNTIME_ASSERT(f >= -1 && f <= 20);
char* str = DoubleToExponentialCString(value, f);
MaybeObject* res =
@ -4274,7 +4274,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_NumberToPrecision) {
return *isolate->factory()->infinity_symbol();
}
CONVERT_DOUBLE_ARG_CHECKED(f_number, 1);
int f = FastD2I(f_number);
int f = FastD2IChecked(f_number);
RUNTIME_ASSERT(f >= 1 && f <= 21);
char* str = DoubleToPrecisionCString(value, f);
MaybeObject* res =

16
test/cctest/test-utils.cc
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@ -55,6 +55,22 @@ TEST(Utils1) {
CHECK_EQ(-2, -8 >> 2);
CHECK_EQ(-2, static_cast<int8_t>(-8) >> 2);
CHECK_EQ(-2, static_cast<int>(static_cast<intptr_t>(-8) >> 2));
CHECK_EQ(-1000000, FastD2IChecked(-1000000.0));
CHECK_EQ(-1, FastD2IChecked(-1.0));
CHECK_EQ(0, FastD2IChecked(0.0));
CHECK_EQ(1, FastD2IChecked(1.0));
CHECK_EQ(1000000, FastD2IChecked(1000000.0));
CHECK_EQ(-1000000, FastD2IChecked(-1000000.123));
CHECK_EQ(-1, FastD2IChecked(-1.234));
CHECK_EQ(0, FastD2IChecked(0.345));
CHECK_EQ(1, FastD2IChecked(1.234));
CHECK_EQ(1000000, FastD2IChecked(1000000.123));
CHECK_EQ(INT_MAX, FastD2IChecked(1.0e100));
CHECK_EQ(INT_MIN, FastD2IChecked(-1.0e100));
CHECK_EQ(INT_MIN, FastD2IChecked(NAN));
}