diff options
Diffstat (limited to 'compiler/compiler.go')
| -rw-r--r-- | compiler/compiler.go | 33 |
1 files changed, 27 insertions, 6 deletions
diff --git a/compiler/compiler.go b/compiler/compiler.go index ea0d51a67..dda5f51eb 100644 --- a/compiler/compiler.go +++ b/compiler/compiler.go @@ -23,7 +23,7 @@ import ( // Version of the compiler pacakge. Must be incremented each time the compiler // package changes in a way that affects the generated LLVM module. // This version is independent of the TinyGo version number. -const Version = 15 // last change: add crypto assembly aliases +const Version = 16 // last change: fix max slice size func init() { llvm.InitializeAllTargets() @@ -1439,6 +1439,28 @@ func (b *builder) getValue(expr ssa.Value) llvm.Value { } } +// maxSliceSize determines the maximum size a slice of the given element type +// can be. +func (c *compilerContext) maxSliceSize(elementType llvm.Type) uint64 { + // Calculate ^uintptr(0), which is the max value that fits in uintptr. + maxPointerValue := llvm.ConstNot(llvm.ConstInt(c.uintptrType, 0, false)).ZExtValue() + // Calculate (^uint(0))/2, which is the max value that fits in an int. + maxIntegerValue := llvm.ConstNot(llvm.ConstInt(c.intType, 0, false)).ZExtValue() / 2 + + // Determine the maximum allowed size for a slice. The biggest possible + // pointer (starting from 0) would be maxPointerValue*sizeof(elementType) so + // divide by the element type to get the real maximum size. + maxSize := maxPointerValue / c.targetData.TypeAllocSize(elementType) + + // len(slice) is an int. Make sure the length remains small enough to fit in + // an int. + if maxSize > maxIntegerValue { + maxSize = maxIntegerValue + } + + return maxSize +} + // createExpr translates a Go SSA expression to LLVM IR. This can be zero, one, // or multiple LLVM IR instructions and/or runtime calls. func (b *builder) createExpr(expr ssa.Value) (llvm.Value, error) { @@ -1652,10 +1674,8 @@ func (b *builder) createExpr(expr ssa.Value) (llvm.Value, error) { elemSize := b.targetData.TypeAllocSize(llvmElemType) elemSizeValue := llvm.ConstInt(b.uintptrType, elemSize, false) - // Calculate (^uintptr(0)) >> 1, which is the max value that fits in - // uintptr if uintptr were signed. - maxSize := llvm.ConstLShr(llvm.ConstNot(llvm.ConstInt(b.uintptrType, 0, false)), llvm.ConstInt(b.uintptrType, 1, false)) - if elemSize > maxSize.ZExtValue() { + maxSize := b.maxSliceSize(llvmElemType) + if elemSize > maxSize { // This seems to be checked by the typechecker already, but let's // check it again just to be sure. return llvm.Value{}, b.makeError(expr.Pos(), fmt.Sprintf("slice element type is too big (%v bytes)", elemSize)) @@ -1664,7 +1684,8 @@ func (b *builder) createExpr(expr ssa.Value) (llvm.Value, error) { // Bounds checking. lenType := expr.Len.Type().Underlying().(*types.Basic) capType := expr.Cap.Type().Underlying().(*types.Basic) - b.createSliceBoundsCheck(maxSize, sliceLen, sliceCap, sliceCap, lenType, capType, capType) + maxSizeValue := llvm.ConstInt(b.uintptrType, maxSize, false) + b.createSliceBoundsCheck(maxSizeValue, sliceLen, sliceCap, sliceCap, lenType, capType, capType) // Allocate the backing array. sliceCapCast, err := b.createConvert(expr.Cap.Type(), types.Typ[types.Uintptr], sliceCap, expr.Pos()) |