[Vm-dev] Serious inlining problem

[Eliot Miranda]

Hi Nicolas,

  I'm looking at this now.  Your recent changes have also caused a huge
number of warnings like this:

type mismatch for formal integerValue and actual "pwr - 1" when inlining
pushInteger: in primitiveExponent. Use a cast.
type mismatch for formal reasonCode and actual "(objectMemory
isIntegerObject: index) ifTrue: [PrimErrBadIndex] ifFalse:
[PrimErrBadArgument]" when inlining primitiveFailFor: in primitiveFloatAt.
Use a cast.
type mismatch for formal cond and actual "rcvr = arg" when inlining
booleanCheat: in bytecodePrimIdentical. Use a cast.
type mismatch for formal cond and actual "rcvr = arg" when inlining
booleanCheatSistaV1: in bytecodePrimIdenticalSistaV1. Use a cast.
type mismatch for formal cond and actual "rcvr = arg" when inlining
booleanCheatV4: in bytecodePrimIdenticalV4. Use a cast.
type mismatch for formal reasonCode and actual "(objectMemory isIndexable:
rcvr) ifTrue: [PrimErrBadIndex] ifFalse: [PrimErrBadReceiver]" when
inlining primitiveFailFor: in commonVariable:at:put:cacheIndex:. Use a cast.
type mismatch for formal numSlots and actual "MessageLookupClassIndex + 1"
when inlining eeInstantiateSmallClassIndex:format:numSlots: in
createActualMessageTo:. Use a cast.
type mismatch for formal successBoolean and actual "integerArg ~= 0" when
inlining success: in doPrimitiveDiv:by:. Use a cast.
type mismatch for formal successBoolean and actual "(result >> 60 + 1
bitAnd: 15) <= 1" when inlining success: in doPrimitiveDiv:by:. Use a cast.
type mismatch for formal successBoolean and actual "integerArg ~= 0" when
inlining success: in doPrimitiveMod:by:. Use a cast.
type mismatch for formal successBoolean and actual "(integerResult >> 60 +
1 bitAnd: 15) <= 1" when inlining success: in doPrimitiveMod:by:. Use a
cast.
type mismatch for formal successBoolean and actual "arg ~= 0.0" when
inlining success: in primitiveFloatDivide:byArg:. Use a cast.
type mismatch for formal successBoolean and actual "objectsWritten = 1"
when inlining success: in putLong:toFile:. Use a cast.
type mismatch for formal successBoolean and actual "objectsWritten = 1"
when inlining success: in putShort:toFile:. Use a cast.
type mismatch for formal successBoolean and actual "objectsWritten = 1"
when inlining success: in putWord32:toFile:. Use a cast.

:-(

We have to be careful.  Pharo is trying to release.  I would like a stable
VM.  I would also like a better-inlined VM, so I support what you're
doing.  I'm just worried about timing.

On Wed, Apr 27, 2016 at 12:47 PM, Nicolas Cellier <
nicolas.cellier.aka.nice at gmail.com> wrote:

>
> Hi,
> I changed the compiler flag -Wno-unused-value to -Wunused-value because
> there's no reason to carry dead code. Dead code should ring a bell.
> it seems it uncovers a problem in code generation.
> An example is in code generated for sendInvokeCallbackContext:
>
>        if ((argumentCountOfMethodHeader(methodHeaderOf(GIV(newMethod))))
> == 4) {
>                 /* begin push: */
>                 value = ((usqInt)((vmCallbackContext->thunkp)));
>                 /* begin positive32BitIntegerFor: */
>                 /* begin maybeInlinePositive32BitIntegerFor: */
>                 assert(!((hasSixtyFourBitImmediates())));
>                 if ((((unsigned int) value)) <= (MaxSmallInteger)) {
>                         ((value << 1) | 1);
>                        ^~~~~~~~~~~~~~ PROBLEM HERE: this result should be
> stored in variable 'object'
>                         goto l4;
>                 }
>                 /* begin eeInstantiateSmallClassIndex:format:numSlots: */
> ...snip...
>                 object = newLargeInteger;
>         l4:     /* end maybeInlinePositive32BitIntegerFor: */;
>                 goto l5;
>
>         l5:     /* end positive32BitIntegerFor: */;
>
>                 longAtput((sp = GIV(stackPointer) - BytesPerWord), object);
>
> The corresponding Slang code is:
>
>     (self argumentCountOf: newMethod) = 4 ifTrue:
>         [self push: (self positiveMachineIntegerFor: vmCallbackContext
> thunkp asUnsignedInteger).
>
> With push:
>
>     | sp |
>     <inline: true>
>     <var: #sp type: #'char *'>
>     stackPages longAt: (sp := stackPointer - objectMemory wordSize) put:
> object.
>     stackPointer := sp
>
> With positiveMachineIntegerFor:
>
>     <var: #value type: #'unsigned long'>
>     <inline: true>
>     ^objectMemory wordSize = 8
>         ifTrue: [self positive64BitIntegerFor: value]
>         ifFalse: [self positive32BitIntegerFor: value]
>
> With positive32BitIntegerFor:
>
>     <inline: true>
>     <var: 'integerValue' type: #'unsigned int'>
>     objectMemory hasSixtyFourBitImmediates
>         ifTrue:
>             [^objectMemory integerObjectOf: (integerValue asUnsignedLong
> bitAnd: 16rFFFFFFFF)]
>         ifFalse:
>             [^self maybeInlinePositive32BitIntegerFor: integerValue]
>
> With maybeInlinePositive32BitIntegerFor:
>
>     <notOption: #Spur64BitMemoryManager>
>     <var: 'integerValue' type: #'unsigned int'>
>     | newLargeInteger |
>     self deny: objectMemory hasSixtyFourBitImmediates.
>        "force coercion because slang inliner sometimes incorrectly pass a
> signed int without converting to unsigned"
>        (self cCode: [self cCoerceSimple: integerValue to: #'unsigned int']
>             inSmalltalk: [integerValue bitAnd: 1 << 32 - 1]) <=
> objectMemory maxSmallInteger ifTrue:
>         [^objectMemory integerObjectOf: integerValue].
>     newLargeInteger := objectMemory
>                             eeInstantiateSmallClassIndex:
>     ...snip...
>     ^newLargeInteger
>
>
>


-- 
_,,,^..^,,,_
best, Eliot
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