Title: [197374] trunk/Source/_javascript_Core
Revision
197374
Author
fpi...@apple.com
Date
2016-02-29 16:39:20 -0800 (Mon, 29 Feb 2016)

Log Message

SpeculatedType should be easier to edit
https://bugs.webkit.org/show_bug.cgi?id=154840

Reviewed by Mark Lam.

We used to specify the bitmasks in SpeculatedType.h using hex codes. This used to work
great because we didn't have so many masks and you could use the mask to visually see
which ones overlapped. It also made it easy to visualize subset relationships.

But now we have a lot of masks with a lot of confusing overlaps, and it's no longer
possible to just see their relationship by looking at hex codes. Worse, the use of hex
codes makes it super annoying to move the bits around. For example, right now we have two
bits free, but if we wanted to reclaim them by editing the old hex masks, it would be a
nightmare.

So this patch replaces the hex masks with shift expressions (1u << 15 for example) and it
makes any derived masks (i.e. masks that are the bit-or of other masks) be expressed using
an or _expression_ (SpecFoo | SpecBar | SpecBaz for example).

This makes it easier to see the relationships and it makes it easier to take bits for new
types.

* bytecode/SpeculatedType.h:

Modified Paths

Diff

Modified: trunk/Source/_javascript_Core/ChangeLog (197373 => 197374)


--- trunk/Source/_javascript_Core/ChangeLog	2016-03-01 00:08:27 UTC (rev 197373)
+++ trunk/Source/_javascript_Core/ChangeLog	2016-03-01 00:39:20 UTC (rev 197374)
@@ -1,3 +1,29 @@
+2016-02-29  Filip Pizlo  <fpi...@apple.com>
+
+        SpeculatedType should be easier to edit
+        https://bugs.webkit.org/show_bug.cgi?id=154840
+
+        Reviewed by Mark Lam.
+
+        We used to specify the bitmasks in SpeculatedType.h using hex codes. This used to work
+        great because we didn't have so many masks and you could use the mask to visually see
+        which ones overlapped. It also made it easy to visualize subset relationships.
+
+        But now we have a lot of masks with a lot of confusing overlaps, and it's no longer
+        possible to just see their relationship by looking at hex codes. Worse, the use of hex
+        codes makes it super annoying to move the bits around. For example, right now we have two
+        bits free, but if we wanted to reclaim them by editing the old hex masks, it would be a
+        nightmare.
+
+        So this patch replaces the hex masks with shift expressions (1u << 15 for example) and it
+        makes any derived masks (i.e. masks that are the bit-or of other masks) be expressed using
+        an or _expression_ (SpecFoo | SpecBar | SpecBaz for example).
+
+        This makes it easier to see the relationships and it makes it easier to take bits for new
+        types.
+
+        * bytecode/SpeculatedType.h:
+
 2016-02-29  Keith Miller  <keith_mil...@apple.com>
 
         OverridesHasInstance constant folding is wrong

Modified: trunk/Source/_javascript_Core/bytecode/SpeculatedType.h (197373 => 197374)


--- trunk/Source/_javascript_Core/bytecode/SpeculatedType.h	2016-03-01 00:08:27 UTC (rev 197373)
+++ trunk/Source/_javascript_Core/bytecode/SpeculatedType.h	2016-03-01 00:39:20 UTC (rev 197374)
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011-2015 Apple Inc. All rights reserved.
+ * Copyright (C) 2011-2016 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -38,57 +38,57 @@
 class Structure;
 
 typedef uint32_t SpeculatedType;
-static const SpeculatedType SpecNone               = 0x00000000; // We don't know anything yet.
-static const SpeculatedType SpecFinalObject        = 0x00000001; // It's definitely a JSFinalObject.
-static const SpeculatedType SpecArray              = 0x00000002; // It's definitely a JSArray.
-static const SpeculatedType SpecFunction           = 0x00000004; // It's definitely a JSFunction.
-static const SpeculatedType SpecInt8Array          = 0x00000008; // It's definitely an Int8Array or one of its subclasses.
-static const SpeculatedType SpecInt16Array         = 0x00000010; // It's definitely an Int16Array or one of its subclasses.
-static const SpeculatedType SpecInt32Array         = 0x00000020; // It's definitely an Int32Array or one of its subclasses.
-static const SpeculatedType SpecUint8Array         = 0x00000040; // It's definitely an Uint8Array or one of its subclasses.
-static const SpeculatedType SpecUint8ClampedArray  = 0x00000080; // It's definitely an Uint8ClampedArray or one of its subclasses.
-static const SpeculatedType SpecUint16Array        = 0x00000100; // It's definitely an Uint16Array or one of its subclasses.
-static const SpeculatedType SpecUint32Array        = 0x00000200; // It's definitely an Uint32Array or one of its subclasses.
-static const SpeculatedType SpecFloat32Array       = 0x00000400; // It's definitely an Uint16Array or one of its subclasses.
-static const SpeculatedType SpecFloat64Array       = 0x00000800; // It's definitely an Uint16Array or one of its subclasses.
+static const SpeculatedType SpecNone               = 0; // We don't know anything yet.
+static const SpeculatedType SpecFinalObject        = 1u << 0; // It's definitely a JSFinalObject.
+static const SpeculatedType SpecArray              = 1u << 1; // It's definitely a JSArray.
+static const SpeculatedType SpecFunction           = 1u << 2; // It's definitely a JSFunction.
+static const SpeculatedType SpecInt8Array          = 1u << 3; // It's definitely an Int8Array or one of its subclasses.
+static const SpeculatedType SpecInt16Array         = 1u << 4; // It's definitely an Int16Array or one of its subclasses.
+static const SpeculatedType SpecInt32Array         = 1u << 5; // It's definitely an Int32Array or one of its subclasses.
+static const SpeculatedType SpecUint8Array         = 1u << 6; // It's definitely an Uint8Array or one of its subclasses.
+static const SpeculatedType SpecUint8ClampedArray  = 1u << 7; // It's definitely an Uint8ClampedArray or one of its subclasses.
+static const SpeculatedType SpecUint16Array        = 1u << 8; // It's definitely an Uint16Array or one of its subclasses.
+static const SpeculatedType SpecUint32Array        = 1u << 9; // It's definitely an Uint32Array or one of its subclasses.
+static const SpeculatedType SpecFloat32Array       = 1u << 10; // It's definitely an Uint16Array or one of its subclasses.
+static const SpeculatedType SpecFloat64Array       = 1u << 11; // It's definitely an Uint16Array or one of its subclasses.
 static const SpeculatedType SpecTypedArrayView     = SpecInt8Array | SpecInt16Array | SpecInt32Array | SpecUint8Array | SpecUint8ClampedArray | SpecUint16Array | SpecUint32Array | SpecFloat32Array | SpecFloat64Array;
-static const SpeculatedType SpecDirectArguments    = 0x00001000; // It's definitely a DirectArguments object.
-static const SpeculatedType SpecScopedArguments    = 0x00002000; // It's definitely a ScopedArguments object.
-static const SpeculatedType SpecStringObject       = 0x00004000; // It's definitely a StringObject.
-static const SpeculatedType SpecObjectOther        = 0x00008000; // It's definitely an object but not JSFinalObject, JSArray, or JSFunction.
-static const SpeculatedType SpecObject             = 0x0000ffff; // Bitmask used for testing for any kind of object prediction.
-static const SpeculatedType SpecStringIdent        = 0x00010000; // It's definitely a JSString, and it's an identifier.
-static const SpeculatedType SpecStringVar          = 0x00020000; // It's definitely a JSString, and it's not an identifier.
-static const SpeculatedType SpecString             = 0x00030000; // It's definitely a JSString.
-static const SpeculatedType SpecSymbol             = 0x00040000; // It's definitely a Symbol.
-static const SpeculatedType SpecCellOther          = 0x00080000; // It's definitely a JSCell but not a subclass of JSObject and definitely not a JSString or a Symbol. FIXME: This shouldn't be part of heap-top or bytecode-top. https://bugs.webkit.org/show_bug.cgi?id=133078
-static const SpeculatedType SpecCell               = 0x000fffff; // It's definitely a JSCell.
-static const SpeculatedType SpecBoolInt32          = 0x00100000; // It's definitely an Int32 with value 0 or 1.
-static const SpeculatedType SpecNonBoolInt32       = 0x00200000; // It's definitely an Int32 with value other than 0 or 1.
-static const SpeculatedType SpecInt32              = 0x00300000; // It's definitely an Int32.
-static const SpeculatedType SpecInt52              = 0x00400000; // It's definitely an Int52 and we intend it to unbox it.
-static const SpeculatedType SpecMachineInt         = 0x00700000; // It's something that we can do machine int arithmetic on.
-static const SpeculatedType SpecInt52AsDouble      = 0x00800000; // It's definitely an Int52 and it's inside a double.
-static const SpeculatedType SpecInteger            = 0x00f00000; // It's definitely some kind of integer.
-static const SpeculatedType SpecNonIntAsDouble     = 0x01000000; // It's definitely not an Int52 but it's a real number and it's a double.
-static const SpeculatedType SpecDoubleReal         = 0x01800000; // It's definitely a non-NaN double.
-static const SpeculatedType SpecDoublePureNaN      = 0x02000000; // It's definitely a NaN that is sae to tag (i.e. pure).
-static const SpeculatedType SpecDoubleImpureNaN    = 0x04000000; // It's definitely a NaN that is unsafe to tag (i.e. impure).
-static const SpeculatedType SpecDoubleNaN          = 0x06000000; // It's definitely some kind of NaN.
-static const SpeculatedType SpecBytecodeDouble     = 0x03800000; // It's either a non-NaN or a NaN double, but it's definitely not impure NaN.
-static const SpeculatedType SpecFullDouble         = 0x07800000; // It's either a non-NaN or a NaN double.
-static const SpeculatedType SpecBytecodeRealNumber = 0x01b00000; // It's either an Int32 or a DoubleReal.
-static const SpeculatedType SpecFullRealNumber     = 0x01f00000; // It's either an Int32 or a DoubleReal, or a Int52.
-static const SpeculatedType SpecBytecodeNumber     = 0x03b00000; // It's either an Int32 or a Double, and the Double cannot be an impure NaN.
-static const SpeculatedType SpecFullNumber         = 0x07f00000; // It's either an Int32, Int52, or a Double, and the Double can be impure NaN.
-static const SpeculatedType SpecBoolean            = 0x10000000; // It's definitely a Boolean.
-static const SpeculatedType SpecOther              = 0x20000000; // It's definitely either Null or Undefined.
-static const SpeculatedType SpecMisc               = 0x30000000; // It's definitely either a boolean, Null, or Undefined.
-static const SpeculatedType SpecHeapTop            = 0x3bbfffff; // It can be any of the above, except for SpecInt52 and SpecDoubleImpureNaN.
-static const SpeculatedType SpecPrimitive          = 0x3bbf0000; // It's any non-Object JSValue. This is (~SpecObject & SpecHeapTop)
-static const SpeculatedType SpecEmpty              = 0x40000000; // It's definitely an empty value marker.
-static const SpeculatedType SpecBytecodeTop        = 0x7bbfffff; // It can be any of the above, except for SpecInt52 and SpecDoubleImpureNaN. This is (SpecHeapTop | SpecEmpty).
-static const SpeculatedType SpecFullTop            = 0x7fffffff; // It can be any of the above plus anything the DFG chooses.
+static const SpeculatedType SpecDirectArguments    = 1u << 12; // It's definitely a DirectArguments object.
+static const SpeculatedType SpecScopedArguments    = 1u << 13; // It's definitely a ScopedArguments object.
+static const SpeculatedType SpecStringObject       = 1u << 14; // It's definitely a StringObject.
+static const SpeculatedType SpecObjectOther        = 1u << 15; // It's definitely an object but not JSFinalObject, JSArray, or JSFunction.
+static const SpeculatedType SpecObject             = SpecFinalObject | SpecArray | SpecFunction | SpecTypedArrayView | SpecDirectArguments | SpecScopedArguments | SpecStringObject | SpecObjectOther; // Bitmask used for testing for any kind of object prediction.
+static const SpeculatedType SpecStringIdent        = 1u << 16; // It's definitely a JSString, and it's an identifier.
+static const SpeculatedType SpecStringVar          = 1u << 17; // It's definitely a JSString, and it's not an identifier.
+static const SpeculatedType SpecString             = SpecStringIdent | SpecStringVar; // It's definitely a JSString.
+static const SpeculatedType SpecSymbol             = 1u << 18; // It's definitely a Symbol.
+static const SpeculatedType SpecCellOther          = 1u << 19; // It's definitely a JSCell but not a subclass of JSObject and definitely not a JSString or a Symbol. FIXME: This shouldn't be part of heap-top or bytecode-top. https://bugs.webkit.org/show_bug.cgi?id=133078
+static const SpeculatedType SpecCell               = SpecObject | SpecString | SpecSymbol | SpecCellOther; // It's definitely a JSCell.
+static const SpeculatedType SpecBoolInt32          = 1u << 20; // It's definitely an Int32 with value 0 or 1.
+static const SpeculatedType SpecNonBoolInt32       = 1u << 21; // It's definitely an Int32 with value other than 0 or 1.
+static const SpeculatedType SpecInt32              = SpecBoolInt32 | SpecNonBoolInt32; // It's definitely an Int32.
+static const SpeculatedType SpecInt52              = 1u << 22; // It's definitely an Int52 and we intend it to unbox it.
+static const SpeculatedType SpecMachineInt         = SpecInt32 | SpecInt52; // It's something that we can do machine int arithmetic on.
+static const SpeculatedType SpecInt52AsDouble      = 1u << 23; // It's definitely an Int52 and it's inside a double.
+static const SpeculatedType SpecInteger            = SpecMachineInt | SpecInt52AsDouble; // It's definitely some kind of integer.
+static const SpeculatedType SpecNonIntAsDouble     = 1u << 24; // It's definitely not an Int52 but it's a real number and it's a double.
+static const SpeculatedType SpecDoubleReal         = SpecNonIntAsDouble | SpecInt52AsDouble; // It's definitely a non-NaN double.
+static const SpeculatedType SpecDoublePureNaN      = 1u << 25; // It's definitely a NaN that is sae to tag (i.e. pure).
+static const SpeculatedType SpecDoubleImpureNaN    = 1u << 26; // It's definitely a NaN that is unsafe to tag (i.e. impure).
+static const SpeculatedType SpecDoubleNaN          = SpecDoublePureNaN | SpecDoubleImpureNaN; // It's definitely some kind of NaN.
+static const SpeculatedType SpecBytecodeDouble     = SpecDoubleReal | SpecDoublePureNaN; // It's either a non-NaN or a NaN double, but it's definitely not impure NaN.
+static const SpeculatedType SpecFullDouble         = SpecDoubleReal | SpecDoubleNaN; // It's either a non-NaN or a NaN double.
+static const SpeculatedType SpecBytecodeRealNumber = SpecInt32 | SpecDoubleReal; // It's either an Int32 or a DoubleReal.
+static const SpeculatedType SpecFullRealNumber     = SpecMachineInt | SpecDoubleReal; // It's either an Int32 or a DoubleReal, or a Int52.
+static const SpeculatedType SpecBytecodeNumber     = SpecInt32 | SpecBytecodeDouble; // It's either an Int32 or a Double, and the Double cannot be an impure NaN.
+static const SpeculatedType SpecFullNumber         = SpecMachineInt | SpecFullDouble; // It's either an Int32, Int52, or a Double, and the Double can be impure NaN.
+static const SpeculatedType SpecBoolean            = 1u << 27; // It's definitely a Boolean.
+static const SpeculatedType SpecOther              = 1u << 28; // It's definitely either Null or Undefined.
+static const SpeculatedType SpecMisc               = SpecBoolean | SpecOther; // It's definitely either a boolean, Null, or Undefined.
+static const SpeculatedType SpecHeapTop            = SpecCell | SpecBytecodeNumber | SpecMisc; // It can be any of the above, except for SpecInt52 and SpecDoubleImpureNaN.
+static const SpeculatedType SpecPrimitive          = SpecString | SpecSymbol | SpecBytecodeNumber | SpecMisc; // It's any non-Object JSValue. This is (~SpecObject & SpecHeapTop)
+static const SpeculatedType SpecEmpty              = 1u << 29; // It's definitely an empty value marker.
+static const SpeculatedType SpecBytecodeTop        = SpecHeapTop | SpecEmpty; // It can be any of the above, except for SpecInt52 and SpecDoubleImpureNaN. Corresponds to what could be found in a bytecode local.
+static const SpeculatedType SpecFullTop            = SpecBytecodeTop | SpecFullNumber; // It can be anything that bytecode could see plus exotic encodings of numbers.
 
 typedef bool (*SpeculatedTypeChecker)(SpeculatedType);
 
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