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[turbofan] Smartify typing of NumberToInt32 and NumberToUint32.

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According to ES5 9.5 and 9.6, NaN, -inf, +inf, -0 and 0 all truncate to
zero for both ToInt32 and ToUint32, so we can be a lot smarter in the
typer, loosing less information upon truncation (i.e. x | 0 and x >>> 0).

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/739743003

Cr-Commit-Position: refs/heads/master@{#25412}
This commit is contained in:
Benedikt Meurer 2014-11-19 08:40:22 +01:00
parent 21580e7b79
commit a39b2f5008
2 changed files with 26 additions and 11 deletions
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35
src/compiler/typer.cc
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@ -39,6 +39,18 @@ Typer::Typer(Graph* graph, MaybeHandle<Context> context)
Handle<Object> infinity = f->NewNumber(+V8_INFINITY);
Handle<Object> minusinfinity = f->NewNumber(-V8_INFINITY);
Type* number = Type::Number();
Type* signed32 = Type::Signed32();
Type* unsigned32 = Type::Unsigned32();
Type* integral32 = Type::Integral32();
Type* object = Type::Object();
Type* undefined = Type::Undefined();
Type* nan_or_minuszero = Type::Union(Type::NaN(), Type::MinusZero(), zone);
Type* truncating_to_zero =
Type::Union(Type::Union(Type::Constant(infinity, zone),
Type::Constant(minusinfinity, zone), zone),
nan_or_minuszero, zone);
negative_signed32 = Type::Union(
Type::SignedSmall(), Type::OtherSigned32(), zone);
non_negative_signed32 = Type::Union(
@ -49,20 +61,13 @@ Typer::Typer(Graph* graph, MaybeHandle<Context> context)
singleton_zero = Type::Range(zero, zero, zone);
singleton_one = Type::Range(one, one, zone);
zero_or_one = Type::Union(singleton_zero, singleton_one, zone);
zeroish = Type::Union(
singleton_zero, Type::Union(Type::NaN(), Type::MinusZero(), zone), zone);
zeroish = Type::Union(singleton_zero, nan_or_minuszero, zone);
signed32ish = Type::Union(signed32, truncating_to_zero, zone);
unsigned32ish = Type::Union(unsigned32, truncating_to_zero, zone);
falsish = Type::Union(Type::Undetectable(),
Type::Union(zeroish, undefined_or_null, zone), zone);
integer = Type::Range(minusinfinity, infinity, zone);
weakint = Type::Union(
integer, Type::Union(Type::NaN(), Type::MinusZero(), zone), zone);
Type* number = Type::Number();
Type* signed32 = Type::Signed32();
Type* unsigned32 = Type::Unsigned32();
Type* integral32 = Type::Integral32();
Type* object = Type::Object();
Type* undefined = Type::Undefined();
weakint = Type::Union(integer, nan_or_minuszero, zone);
number_fun0_ = Type::Function(number, zone);
number_fun1_ = Type::Function(number, number, zone);
@ -467,6 +472,10 @@ Type* Typer::Visitor::NumberToInt32(Type* type, Typer* t) {
// TODO(neis): DCHECK(type->Is(Type::Number()));
if (type->Is(Type::Signed32())) return type;
if (type->Is(t->zeroish)) return t->singleton_zero;
if (type->Is(t->signed32ish)) {
return Type::Intersect(Type::Union(type, t->singleton_zero, t->zone()),
Type::Signed32(), t->zone());
}
return Type::Signed32();
}
@ -475,6 +484,10 @@ Type* Typer::Visitor::NumberToUint32(Type* type, Typer* t) {
// TODO(neis): DCHECK(type->Is(Type::Number()));
if (type->Is(Type::Unsigned32())) return type;
if (type->Is(t->zeroish)) return t->singleton_zero;
if (type->Is(t->unsigned32ish)) {
return Type::Intersect(Type::Union(type, t->singleton_zero, t->zone()),
Type::Unsigned32(), t->zone());
}
return Type::Unsigned32();
}

2
src/compiler/typer.h
View File

@ -47,6 +47,8 @@ class Typer {
Type* singleton_one;
Type* zero_or_one;
Type* zeroish;
Type* signed32ish;
Type* unsigned32ish;
Type* falsish;
Type* integer;
Type* weakint;