57c23b967e
In some cases natural use of abstraction in avo programs can lead to redundant move instructions, specifically self-moves such as MOVQ AX, AX. This does not produce incorrect code but it is incorrect and inelegant. This diff introduces a PruneSelfMoves pass that removes such unnecessary instructions. Closes #76
80 lines
1.8 KiB
Go
80 lines
1.8 KiB
Go
// Package pass implements processing passes on avo Files.
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package pass
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import (
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"io"
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"github.com/mmcloughlin/avo/ir"
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"github.com/mmcloughlin/avo/printer"
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)
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// Compile pass compiles an avo file. Upon successful completion the avo file
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// may be printed to Go assembly.
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var Compile = Concat(
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FunctionPass(LabelTarget),
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FunctionPass(CFG),
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FunctionPass(Liveness),
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FunctionPass(AllocateRegisters),
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FunctionPass(BindRegisters),
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FunctionPass(VerifyAllocation),
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Func(IncludeTextFlagHeader),
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FunctionPass(PruneSelfMoves),
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)
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// Interface for a processing pass.
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type Interface interface {
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Execute(*ir.File) error
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}
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// Func adapts a function to the pass Interface.
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type Func func(*ir.File) error
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// Execute calls p.
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func (p Func) Execute(f *ir.File) error {
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return p(f)
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}
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// FunctionPass is a convenience for implementing a full file pass with a
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// function that operates on each avo Function independently.
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type FunctionPass func(*ir.Function) error
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// Execute calls p on every function in the file. Exits on the first error.
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func (p FunctionPass) Execute(f *ir.File) error {
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for _, fn := range f.Functions() {
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if err := p(fn); err != nil {
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return err
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}
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}
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return nil
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}
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// Concat returns a pass that executes the given passes in order, stopping on the first error.
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func Concat(passes ...Interface) Interface {
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return Func(func(f *ir.File) error {
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for _, p := range passes {
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if err := p.Execute(f); err != nil {
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return err
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}
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}
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return nil
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})
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}
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// Output pass prints a file.
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type Output struct {
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Writer io.WriteCloser
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Printer printer.Printer
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}
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// Execute prints f with the configured Printer and writes output to Writer.
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func (o *Output) Execute(f *ir.File) error {
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b, err := o.Printer.Print(f)
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if err != nil {
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return err
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}
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if _, err = o.Writer.Write(b); err != nil {
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return err
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}
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return o.Writer.Close()
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}
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