4d88d9ed8d
FDEs previously were loaded into a red/black tree and searched. This is significantly more expensive than a binary search over a slice. Not sure what I was thinking using a red/black tree - this binary search implementation is significantly more efficient.
90 lines
2.0 KiB
Go
90 lines
2.0 KiB
Go
package frame
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import "fmt"
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// Represents a Common Information Entry in
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// the Dwarf .debug_frame section.
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type CommonInformationEntry struct {
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Length uint32
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CIE_id uint32
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Version uint8
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Augmentation string
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CodeAlignmentFactor uint64
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DataAlignmentFactor int64
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ReturnAddressRegister uint64
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InitialInstructions []byte
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}
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func (fde *FrameDescriptionEntry) Cover(addr uint64) bool {
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if (addr - fde.begin) < fde.end {
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return true
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}
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return false
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}
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// Represents a Frame Descriptor Entry in the
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// Dwarf .debug_frame section.
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type FrameDescriptionEntry struct {
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Length uint32
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CIE *CommonInformationEntry
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Instructions []byte
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begin, end uint64
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}
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func (fde *FrameDescriptionEntry) Begin() uint64 {
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return fde.begin
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}
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func (fde *FrameDescriptionEntry) End() uint64 {
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return fde.begin + fde.end
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}
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func (fde *FrameDescriptionEntry) EstablishFrame(pc uint64) *FrameContext {
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return executeDwarfProgramUntilPC(fde, pc)
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}
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func (fde *FrameDescriptionEntry) ReturnAddressOffset(pc uint64) int64 {
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frame := fde.EstablishFrame(pc)
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return frame.cfa.offset + frame.regs[fde.CIE.ReturnAddressRegister].offset
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}
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type FrameDescriptionEntries []*FrameDescriptionEntry
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func NewFrameIndex() FrameDescriptionEntries {
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return make(FrameDescriptionEntries, 0, 1000)
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}
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func (fdes FrameDescriptionEntries) FDEForPC(pc uint64) (*FrameDescriptionEntry, error) {
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frame := find(fdes, pc)
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if frame == nil {
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return nil, fmt.Errorf("could not find FDE for %#v", pc)
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}
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return frame, nil
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}
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func find(fdes FrameDescriptionEntries, pc uint64) *FrameDescriptionEntry {
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if len(fdes) == 0 {
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return nil
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}
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idx := len(fdes) / 2
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frame := fdes[idx]
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if frame.Cover(pc) {
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return frame
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}
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if frame.Less(pc) {
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return find(fdes[:idx], pc)
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}
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if frame.More(pc) {
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return find(fdes[idx:], pc)
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}
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return nil
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}
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func (frame *FrameDescriptionEntry) Less(pc uint64) bool {
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return frame.Begin() > pc
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}
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func (frame *FrameDescriptionEntry) More(pc uint64) bool {
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return frame.End() < pc
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}
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