Safe Haskell	None
Language	GHC2021

H2JVM.Analyse.StackMap

Description

Generate a stack map table for a method. This process MUST run last in the high level stage, modifications to the code after this point will invalidate the stack map table and cause invalid class files to be generated.

Synopsis

calculateStackMapFrames :: HasCallStack => QualifiedClassName -> [MethodAccessFlag] -> MethodDescriptor -> NonEmpty Instruction -> Either StackMapError ([StackMapFrame], Int, Int)
data BasicBlock = BasicBlock {
- index :: Int
- instructions :: [Instruction]
- start :: Maybe Label
- end :: Maybe Label
}
data Frame = Frame {
- locals :: [LocalVariable]
- stack :: [StackEntry]
}
data LocalVariable
- = Uninitialised
- | LocalVariable FieldType
analyseBlockDiff :: HasCallStack => Frame -> BasicBlock -> Either StackMapError Frame
diffFrames :: Frame -> Frame -> Label -> StackMapFrame
splitIntoBasicBlocks :: HasCallStack => NonEmpty Instruction -> NonEmpty BasicBlock
topFrame :: QualifiedClassName -> [MethodAccessFlag] -> MethodDescriptor -> Frame
data StackMapError
- = StackUnderflow Instruction
- | InvalidStackState Instruction [StackEntry] (Maybe Text)
- | LocalIndexOutOfBounds Instruction U2 Frame BasicBlock
- | IncompatibleFrameMerge Frame Frame
- | MissingBlockFrame Int

Documentation

calculateStackMapFrames Source #

Arguments

:: HasCallStack
=> QualifiedClassName	The class containing this method
-> [MethodAccessFlag]	Method access flags (to determine if static)
-> MethodDescriptor	The method descriptor
-> NonEmpty Instruction	The method's instruction list
-> Either StackMapError ([StackMapFrame], Int, Int)	(stack map frames, max stack, max locals)

Calculate the stack map frames for a method's bytecode. This function works by first splitting the code into basic blocks, then computing the frame state at the start of each block using a dataflow analysis, and finally generating the stack map frames by comparing the frame states at block entries.

data BasicBlock Source #

A basic block is a sequence of instructions with a single entry and exit point. Control flow only enters at the beginning and exits at the end.

Constructors

BasicBlock
Fields index :: Int The index of this block in the method's block list instructions :: [Instruction] The instructions in this block (excluding the starting label) start :: Maybe Label The label at the start of this block, if any end :: Maybe Label The label that the next block starts with, if any

Instances

Instances details

Show BasicBlock Source #
Instance details Defined in H2JVM.Analyse.StackMap Methods showsPrec :: Int -> BasicBlock -> ShowS # show :: BasicBlock -> String # showList :: [BasicBlock] -> ShowS #
Eq BasicBlock Source #
Instance details Defined in H2JVM.Analyse.StackMap Methods (==) :: BasicBlock -> BasicBlock -> Bool # (/=) :: BasicBlock -> BasicBlock -> Bool #

data Frame Source #

Represents the JVM frame state at a particular program point.

Constructors

Frame
Fields locals :: [LocalVariable] The local variable slots stack :: [StackEntry] The operand stack, with the top of stack at the head

Instances

Instances details

Show Frame Source #
Instance details Defined in H2JVM.Analyse.StackMap Methods showsPrec :: Int -> Frame -> ShowS # show :: Frame -> String # showList :: [Frame] -> ShowS #
Eq Frame Source #
Instance details Defined in H2JVM.Analyse.StackMap Methods (==) :: Frame -> Frame -> Bool # (/=) :: Frame -> Frame -> Bool #

data LocalVariable Source #

Represents the type of a local variable slot in the stack frame

Constructors

Uninitialised	The slot has not been initialised or contains an unusable value
LocalVariable FieldType	The slot contains a value of the given type

Instances

Instances details

Show LocalVariable Source #
Instance details Defined in H2JVM.Analyse.StackMap Methods showsPrec :: Int -> LocalVariable -> ShowS # show :: LocalVariable -> String # showList :: [LocalVariable] -> ShowS #
Eq LocalVariable Source #
Instance details Defined in H2JVM.Analyse.StackMap Methods (==) :: LocalVariable -> LocalVariable -> Bool # (/=) :: LocalVariable -> LocalVariable -> Bool #
Pretty LocalVariable Source #
Instance details Defined in H2JVM.Analyse.StackMap Methods pretty :: LocalVariable -> Doc ann Source # prettyList :: [LocalVariable] -> Doc ann Source #

analyseBlockDiff :: HasCallStack => Frame -> BasicBlock -> Either StackMapError Frame Source #

Compute the frame state after executing all instructions in a basic block.

diffFrames :: Frame -> Frame -> Label -> StackMapFrame Source #

Compute the delta between two frames to produce a StackMapFrame

splitIntoBasicBlocks :: HasCallStack => NonEmpty Instruction -> NonEmpty BasicBlock Source #

Split a list of instructions into basic blocks, by splitting at labels and branch instructions.

topFrame :: QualifiedClassName -> [MethodAccessFlag] -> MethodDescriptor -> Frame Source #

Compute the initial frame state at method entry (the "top frame"), based on the method descriptor and access flags (static vs instance).

data StackMapError Source #

Constructors

StackUnderflow Instruction
InvalidStackState Instruction [StackEntry] (Maybe Text)
LocalIndexOutOfBounds Instruction U2 Frame BasicBlock
IncompatibleFrameMerge Frame Frame
MissingBlockFrame Int

Instances

Instances details

Show StackMapError Source #
Instance details Defined in H2JVM.Analyse.StackMap Methods showsPrec :: Int -> StackMapError -> ShowS # show :: StackMapError -> String # showList :: [StackMapError] -> ShowS #