3b4544ee48
This removes the embedding of pointers of jump tables (uintptr of []byte) used by BrTable operations. That is the last usage of unsafe.Pointer in compiler implementations. Alternatively, we treat jump tables as asm.StaticConst and emit them into the constPool already implemented and used by various places. Notably, now the native code compiled by compilers can be reusable across multiple processes, meaning that they are independent of any runtime pointers. Signed-off-by: Takeshi Yoneda <takeshi@tetrate.io>
47 lines
1.8 KiB
Go
47 lines
1.8 KiB
Go
package asm
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import (
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"encoding/binary"
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"fmt"
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)
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// BaseAssemblerImpl includes code common to all architectures.
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//
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// Note: When possible, add code here instead of in architecture-specific files to reduce drift:
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// As this is internal, exporting symbols only to reduce duplication is ok.
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type BaseAssemblerImpl struct {
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// SetBranchTargetOnNextNodes holds branch kind instructions (BR, conditional BR, etc.)
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// where we want to set the next coming instruction as the destination of these BR instructions.
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SetBranchTargetOnNextNodes []Node
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// OnGenerateCallbacks holds the callbacks which are called after generating native code.
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OnGenerateCallbacks []func(code []byte) error
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}
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// SetJumpTargetOnNext implements AssemblerBase.SetJumpTargetOnNext
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func (a *BaseAssemblerImpl) SetJumpTargetOnNext(nodes ...Node) {
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a.SetBranchTargetOnNextNodes = append(a.SetBranchTargetOnNextNodes, nodes...)
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}
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// AddOnGenerateCallBack implements AssemblerBase.AddOnGenerateCallBack
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func (a *BaseAssemblerImpl) AddOnGenerateCallBack(cb func([]byte) error) {
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a.OnGenerateCallbacks = append(a.OnGenerateCallbacks, cb)
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}
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// BuildJumpTable implements AssemblerBase.BuildJumpTable
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func (a *BaseAssemblerImpl) BuildJumpTable(table *StaticConst, labelInitialInstructions []Node) {
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a.AddOnGenerateCallBack(func(code []byte) error {
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// Compile the offset table for each target.
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base := labelInitialInstructions[0].OffsetInBinary()
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for i, nop := range labelInitialInstructions {
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if nop.OffsetInBinary()-base >= JumpTableMaximumOffset {
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return fmt.Errorf("too large br_table")
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}
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// We store the offset from the beginning of the L0's initial instruction.
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binary.LittleEndian.PutUint32(code[table.offsetInBinary+uint64(i*4):table.offsetInBinary+uint64((i+1)*4)],
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uint32(nop.OffsetInBinary())-uint32(base))
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}
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return nil
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})
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}
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