DeoptimizationStub (Graal OpenJDK Project Documentation)

java.lang.Object
- com.oracle.graal.hotspot.stubs.Stub
- - com.oracle.graal.hotspot.stubs.SnippetStub
  - - com.oracle.graal.hotspot.stubs.DeoptimizationStub

All Implemented Interfaces:

Snippets

Direct Known Subclasses:

AMD64DeoptimizationStub, SPARCDeoptimizationStub
```
public class DeoptimizationStub
extends SnippetStub
```
Deoptimization stub. This is the entry point for code which is returning to a de-optimized frame. The steps taken by this frame are as follows:
push a dummy "register_save" and save the return values (O0, O1, F0/F1, G1) and all potentially live registers (at a pollpoint many registers can be live).
call the C routine: Deoptimization::fetch_unroll_info (this function returns information about the number and size of interpreter frames which are equivalent to the frame which is being deoptimized)
deallocate the unpack frame, restoring only results values. Other volatile registers will now be captured in the vframeArray as needed.
deallocate the deoptimization frame
in a loop using the information returned in the previous step push new interpreter frames (take care to propagate the return values through each new frame pushed)
create a dummy "unpack_frame" and save the return values (O0, O1, F0)
call the C routine: Deoptimization::unpack_frames (this function lays out values on the interpreter frame which was just created)
deallocate the dummy unpack_frame
ensure that all the return values are correctly set and then do a return to the interpreter entry point
ATTENTION: We cannot do any complicated operations e.g. logging via printf in this snippet because we change the current stack layout and so the code is very sensitive to register allocation.

Field Summary

Fields
Modifier and Type Field and Description

private TargetDescription target
- Fields inherited from class com.oracle.graal.hotspot.stubs.SnippetStub
  method, SnippetGraphUnderConstruction
- Fields inherited from class com.oracle.graal.hotspot.stubs.Stub
  code, compResult, linkage, providers

Fields
Modifier and Type	Field and Description
`private TargetDescription`	`target`

Constructor Summary

Constructors
Constructor and Description

DeoptimizationStub(HotSpotProviders providers, TargetDescription target, HotSpotForeignCallLinkage linkage)

Constructors
Constructor and Description
`DeoptimizationStub(HotSpotProviders providers, TargetDescription target, HotSpotForeignCallLinkage linkage)`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`private static void`	`deoptimizationHandler(Register threadRegister, Register stackPointerRegister)` Deoptimization handler for normal deoptimization `HotSpotVMConfig.deoptimizationUnpackDeopt`.
`private static int`	`deoptimizationUnpackDeopt()`
`private static int`	`deoptimizationUnpackUncommonTrap()`
`private static int`	`deoptimizationUnrollBlockCallerAdjustmentOffset()`
`private static int`	`deoptimizationUnrollBlockFramePcsOffset()`
`private static int`	`deoptimizationUnrollBlockFrameSizesOffset()`
`private static int`	`deoptimizationUnrollBlockInitialInfoOffset()`
`private static int`	`deoptimizationUnrollBlockNumberOfFramesOffset()`
`private static int`	`deoptimizationUnrollBlockSizeOfDeoptimizedFrameOffset()`
`private static int`	`deoptimizationUnrollBlockTotalFrameSizesOffset()`
`protected Object`	`getConstantParameterValue(int index, String name)`
`boolean`	`preservesRegisters()` Determines if this stub preserves all registers apart from those it destroys.
`private static Word`	`readRegister(Register register)` Reads the value of the passed register as a Word.
`private static int`	`stackBias()` Deprecated. This method should go away as soon as JDK-8032410 hits the Graal repository.
`private static int`	`stackShadowPages()`
`static int`	`unpackFrames(ForeignCallDescriptor unpackFrames, Word thread, int mode)`
`private static void`	`writeRegister(Register register, Word value)` Writes the value of the passed register.

Methods inherited from class com.oracle.graal.hotspot.stubs.SnippetStub
checkConstArg, debugScopeContext, getGraph, getInstalledCodeOwner, makeConstArgs, toString

Methods inherited from class com.oracle.graal.hotspot.stubs.Stub
getCode, getCompilationResult, getDestroyedRegisters, getLinkage, getRegisterConfig, getStubs, initDestroyedRegisters

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail
- target
```
private final TargetDescription target
```

Constructor Detail

DeoptimizationStub

public DeoptimizationStub(HotSpotProviders providers,
                          TargetDescription target,
                          HotSpotForeignCallLinkage linkage)

Method Detail

preservesRegisters
```
public boolean preservesRegisters()
```
Description copied from class: Stub

Determines if this stub preserves all registers apart from those it destroys.

Overrides:

preservesRegisters in class Stub

getConstantParameterValue

protected Object getConstantParameterValue(int index,
                                           String name)

Overrides:: getConstantParameterValue in class SnippetStub

deoptimizationHandler

private static void deoptimizationHandler(Register threadRegister,
                                          Register stackPointerRegister)

Deoptimization handler for normal deoptimization HotSpotVMConfig.deoptimizationUnpackDeopt.

readRegister
```
private static Word readRegister(Register register)
```
Reads the value of the passed register as a Word.

writeRegister

private static void writeRegister(Register register,
                                  Word value)

Writes the value of the passed register.

Parameters:: value - value the register should be set to

stackShadowPages
```
private static int stackShadowPages()
```

stackBias
```
@Deprecated
private static int stackBias()
```
Deprecated. This method should go away as soon as JDK-8032410 hits the Graal repository.

Returns the stack bias for the host architecture.

Returns:

stack bias

deoptimizationUnrollBlockSizeOfDeoptimizedFrameOffset

private static int deoptimizationUnrollBlockSizeOfDeoptimizedFrameOffset()

deoptimizationUnrollBlockCallerAdjustmentOffset

private static int deoptimizationUnrollBlockCallerAdjustmentOffset()

deoptimizationUnrollBlockNumberOfFramesOffset

private static int deoptimizationUnrollBlockNumberOfFramesOffset()

deoptimizationUnrollBlockTotalFrameSizesOffset

private static int deoptimizationUnrollBlockTotalFrameSizesOffset()

deoptimizationUnrollBlockFrameSizesOffset

private static int deoptimizationUnrollBlockFrameSizesOffset()

deoptimizationUnrollBlockFramePcsOffset

private static int deoptimizationUnrollBlockFramePcsOffset()

deoptimizationUnrollBlockInitialInfoOffset

private static int deoptimizationUnrollBlockInitialInfoOffset()

deoptimizationUnpackDeopt

private static int deoptimizationUnpackDeopt()

deoptimizationUnpackUncommonTrap

private static int deoptimizationUnpackUncommonTrap()

unpackFrames

public static int unpackFrames(ForeignCallDescriptor unpackFrames,
                               Word thread,
                               int mode)

Class DeoptimizationStub

Field Summary

Fields inherited from class com.oracle.graal.hotspot.stubs.SnippetStub

Fields inherited from class com.oracle.graal.hotspot.stubs.Stub

Constructor Summary

Method Summary

Methods inherited from class com.oracle.graal.hotspot.stubs.SnippetStub

Methods inherited from class com.oracle.graal.hotspot.stubs.Stub

Methods inherited from class java.lang.Object

Field Detail

target

Constructor Detail

DeoptimizationStub

Method Detail

preservesRegisters

getConstantParameterValue

deoptimizationHandler

readRegister

writeRegister

stackShadowPages

stackBias

deoptimizationUnrollBlockSizeOfDeoptimizedFrameOffset

deoptimizationUnrollBlockCallerAdjustmentOffset

deoptimizationUnrollBlockNumberOfFramesOffset

deoptimizationUnrollBlockTotalFrameSizesOffset

deoptimizationUnrollBlockFrameSizesOffset

deoptimizationUnrollBlockFramePcsOffset

deoptimizationUnrollBlockInitialInfoOffset

deoptimizationUnpackDeopt

deoptimizationUnpackUncommonTrap

unpackFrames