Typedefs that resolve to slices are not recorded in DWARF as typedefs
but instead as structs in a way that there is no way to know they
are really slices using debug/dwarf.
Using golang.org/x/debug/dwarf instead this problem is solved and
as a bonus some types are printed with a nicer names: (struct string
→ string, struct []int → []int, etc)
Fixes#356 and #293
Prefetch the entire memory of structs and arrays and cache it instead
of issuing readMemory calls only when we get down to primitive types.
This reduces the number of system calls to ptrace that variables makes.
Improves performance in general, greatly improving it in some
particular cases (involving large structs).
Benchmarks without prefetching:
BenchmarkArray-4 10 132189944 ns/op 0.06 MB/s
BenchmarkArrayPointer-4 5 202538503 ns/op 0.04 MB/s
BenchmarkMap-4 500 3804336 ns/op 0.27 MB/s
BenchmarkGoroutinesInfo-4 10 126397104 ns/op
BenchmarkLocalVariables-4 500 2494846 ns/op
Benchmarks with prefetching:
BenchmarkArray-4 200 10719087 ns/op 0.76 MB/s
BenchmarkArrayPointer-4 100 11931326 ns/op 0.73 MB/s
BenchmarkMap-4 1000 1466479 ns/op 0.70 MB/s
BenchmarkGoroutinesInfo-4 10 103407004 ns/op
BenchmarkLocalVariables-4 1000 1530395 ns/op
Improvement factors:
BenchmarkArray 12.33x
BenchmarkArrayPointer 16.97x
BenchmarkMap 2.59x
BenchmarkGoroutinesInfo 1.22x
BenchmarkLocalVariables 1.63x
The concrete type of an interface only contains the abbreviated
package name, we must construct a map from package names to package
paths to be able to resolve the concrete type of an interface.
Supported operators:
- All (binary and unary) operators between basic types except <-,
++ and -- (includes & to take the address of an expression)
- Comparison operators between supported compound types
- Typecast of integer constants into pointer types
- struct members
- indexing of arrays, slices and strings
- slicing of arrays, slices and strings
- pointer dereferencing
- true, false and nil constants
Implements #116, #117 and #251
