compiler: refactor slice related asserts
Move these asserts into compiler/asserts.go, to keep them together. The make([]T) asserts aren't moved yet because that code is (still!) quite ugly and in need of some clean up.
Этот коммит содержится в:
Ayke van Laethem
Ron Evans
родитель
09e85b7859
коммит
051ad07755
2 изменённых файлов: 76 добавлений и 69 удалений
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@ -4,9 +4,82 @@ package compiler
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// required by the Go programming language.
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import (
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"go/types"
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"tinygo.org/x/go-llvm"
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)
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// emitLookupBoundsCheck emits a bounds check before doing a lookup into a
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// slice. This is required by the Go language spec: an index out of bounds must
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// cause a panic.
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func (c *Compiler) emitLookupBoundsCheck(frame *Frame, arrayLen, index llvm.Value, indexType types.Type) {
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if frame.fn.IsNoBounds() {
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// The //go:nobounds pragma was added to the function to avoid bounds
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// checking.
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return
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}
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// Sometimes, the index can be e.g. an uint8 or int8, and we have to
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// correctly extend that type.
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if index.Type().IntTypeWidth() < arrayLen.Type().IntTypeWidth() {
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if indexType.(*types.Basic).Info()&types.IsUnsigned == 0 {
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index = c.builder.CreateZExt(index, arrayLen.Type(), "")
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} else {
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index = c.builder.CreateSExt(index, arrayLen.Type(), "")
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}
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}
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// Optimize away trivial cases.
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// LLVM would do this anyway with interprocedural optimizations, but it
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// helps to see cases where bounds check elimination would really help.
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if index.IsConstant() && arrayLen.IsConstant() && !arrayLen.IsUndef() {
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index := index.SExtValue()
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arrayLen := arrayLen.SExtValue()
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if index >= 0 && index < arrayLen {
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return
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}
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}
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if index.Type().IntTypeWidth() > c.intType.IntTypeWidth() {
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// Index is too big for the regular bounds check. Use the one for int64.
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c.createRuntimeCall("lookupBoundsCheckLong", []llvm.Value{arrayLen, index}, "")
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} else {
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c.createRuntimeCall("lookupBoundsCheck", []llvm.Value{arrayLen, index}, "")
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}
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}
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// emitSliceBoundsCheck emits a bounds check before a slicing operation to make
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// sure it is within bounds.
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func (c *Compiler) emitSliceBoundsCheck(frame *Frame, capacity, low, high llvm.Value, lowType, highType *types.Basic) {
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if frame.fn.IsNoBounds() {
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// The //go:nobounds pragma was added to the function to avoid bounds
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// checking.
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return
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}
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uintptrWidth := c.uintptrType.IntTypeWidth()
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if low.Type().IntTypeWidth() > uintptrWidth || high.Type().IntTypeWidth() > uintptrWidth {
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if low.Type().IntTypeWidth() < 64 {
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if lowType.Info()&types.IsUnsigned != 0 {
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low = c.builder.CreateZExt(low, c.ctx.Int64Type(), "")
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} else {
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low = c.builder.CreateSExt(low, c.ctx.Int64Type(), "")
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}
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}
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if high.Type().IntTypeWidth() < 64 {
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if highType.Info()&types.IsUnsigned != 0 {
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high = c.builder.CreateZExt(high, c.ctx.Int64Type(), "")
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} else {
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high = c.builder.CreateSExt(high, c.ctx.Int64Type(), "")
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}
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}
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// TODO: 32-bit or even 16-bit slice bounds checks for 8-bit platforms
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c.createRuntimeCall("sliceBoundsCheck64", []llvm.Value{capacity, low, high}, "")
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} else {
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c.createRuntimeCall("sliceBoundsCheck", []llvm.Value{capacity, low, high}, "")
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}
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}
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// emitNilCheck checks whether the given pointer is nil, and panics if it is. It
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// has no effect in well-behaved programs, but makes sure no uncaught nil
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// pointer dereferences exist in valid Go code.
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@ -1413,72 +1413,6 @@ func (c *Compiler) parseCall(frame *Frame, instr *ssa.CallCommon) (llvm.Value, e
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}
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}
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func (c *Compiler) emitBoundsCheck(frame *Frame, arrayLen, index llvm.Value, indexType types.Type) {
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if frame.fn.IsNoBounds() {
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// The //go:nobounds pragma was added to the function to avoid bounds
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// checking.
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return
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}
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// Sometimes, the index can be e.g. an uint8 or int8, and we have to
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// correctly extend that type.
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if index.Type().IntTypeWidth() < arrayLen.Type().IntTypeWidth() {
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if indexType.(*types.Basic).Info()&types.IsUnsigned == 0 {
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index = c.builder.CreateZExt(index, arrayLen.Type(), "")
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} else {
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index = c.builder.CreateSExt(index, arrayLen.Type(), "")
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}
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}
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// Optimize away trivial cases.
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// LLVM would do this anyway with interprocedural optimizations, but it
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// helps to see cases where bounds check elimination would really help.
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if index.IsConstant() && arrayLen.IsConstant() && !arrayLen.IsUndef() {
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index := index.SExtValue()
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arrayLen := arrayLen.SExtValue()
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if index >= 0 && index < arrayLen {
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return
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}
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}
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if index.Type().IntTypeWidth() > c.intType.IntTypeWidth() {
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// Index is too big for the regular bounds check. Use the one for int64.
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c.createRuntimeCall("lookupBoundsCheckLong", []llvm.Value{arrayLen, index}, "")
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} else {
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c.createRuntimeCall("lookupBoundsCheck", []llvm.Value{arrayLen, index}, "")
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}
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}
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func (c *Compiler) emitSliceBoundsCheck(frame *Frame, capacity, low, high llvm.Value, lowType, highType *types.Basic) {
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if frame.fn.IsNoBounds() {
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// The //go:nobounds pragma was added to the function to avoid bounds
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// checking.
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return
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}
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uintptrWidth := c.uintptrType.IntTypeWidth()
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if low.Type().IntTypeWidth() > uintptrWidth || high.Type().IntTypeWidth() > uintptrWidth {
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if low.Type().IntTypeWidth() < 64 {
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if lowType.Info()&types.IsUnsigned != 0 {
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low = c.builder.CreateZExt(low, c.ctx.Int64Type(), "")
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} else {
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low = c.builder.CreateSExt(low, c.ctx.Int64Type(), "")
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}
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}
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if high.Type().IntTypeWidth() < 64 {
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if highType.Info()&types.IsUnsigned != 0 {
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high = c.builder.CreateZExt(high, c.ctx.Int64Type(), "")
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} else {
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high = c.builder.CreateSExt(high, c.ctx.Int64Type(), "")
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}
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}
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// TODO: 32-bit or even 16-bit slice bounds checks for 8-bit platforms
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c.createRuntimeCall("sliceBoundsCheck64", []llvm.Value{capacity, low, high}, "")
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} else {
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c.createRuntimeCall("sliceBoundsCheck", []llvm.Value{capacity, low, high}, "")
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}
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}
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func (c *Compiler) parseExpr(frame *Frame, expr ssa.Value) (llvm.Value, error) {
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if value, ok := frame.locals[expr]; ok {
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// Value is a local variable that has already been computed.
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@ -1623,7 +1557,7 @@ func (c *Compiler) parseExpr(frame *Frame, expr ssa.Value) (llvm.Value, error) {
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// Check bounds.
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arrayLen := expr.X.Type().(*types.Array).Len()
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arrayLenLLVM := llvm.ConstInt(c.uintptrType, uint64(arrayLen), false)
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c.emitBoundsCheck(frame, arrayLenLLVM, index, expr.Index.Type())
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c.emitLookupBoundsCheck(frame, arrayLenLLVM, index, expr.Index.Type())
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// Can't load directly from array (as index is non-constant), so have to
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// do it using an alloca+gep+load.
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@ -1670,7 +1604,7 @@ func (c *Compiler) parseExpr(frame *Frame, expr ssa.Value) (llvm.Value, error) {
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// Bounds check.
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// LLVM optimizes this away in most cases.
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c.emitBoundsCheck(frame, buflen, index, expr.Index.Type())
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c.emitLookupBoundsCheck(frame, buflen, index, expr.Index.Type())
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switch expr.X.Type().Underlying().(type) {
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case *types.Pointer:
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@ -1703,7 +1637,7 @@ func (c *Compiler) parseExpr(frame *Frame, expr ssa.Value) (llvm.Value, error) {
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// Bounds check.
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// LLVM optimizes this away in most cases.
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length := c.builder.CreateExtractValue(value, 1, "len")
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c.emitBoundsCheck(frame, length, index, expr.Index.Type())
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c.emitLookupBoundsCheck(frame, length, index, expr.Index.Type())
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// Lookup byte
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buf := c.builder.CreateExtractValue(value, 0, "")
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