Fixes #186, #83

We need to reset the current file and line number.

Fixes #1008

It can happen if the interface variable escaped, it's out of scope and
we autodereference it.

On macOS, externally linked programs will have an abbrev for
DW_TAG_subprogram without the haschildren flag set. We should handle
this case instead of expecting all DW_TAG_subprogram entries to have
list of children.

Fixes #1034

Prints the frame and frame pointer offsets for each frame.

When creating a stack trace we should switch between the goroutine
stack and the system stack (where cgo code is executed) as appropriate
to reconstruct the logical stacktrace.

Goroutines that are currently executing on the system stack will have
the SystemStack flag set, frames of the goroutine stack will have a
negative FrameOffset (like always) and frames of the system stack will
have a positive FrameOffset (which is actually just the CFA value for
the frame).

Updates #935

Pass CGO_FLAGS='-O0 -g' to go build to disable optimizations when
calling the C compiler.

* Support --output for debug, trace, and test commands

With the `--output` parameter you can configure the output binary. For
example:

    dlv debug --output /tmp/xxx

Will build the binary to `/tmp/xxx`, instead of always putting it as
`debug` in the current directory.

This ensures that the command always works (even if there is already a
file or directory named `debug`) and doesn't write to the source
directory. Especially for things like Delve/Vim integration this is a
good thing to have, I think.

* Address PR feedback and add a test

- We don't need to use `filepath.IsAbs()` on startup; I added that
  because it previously did `"./" + debugname` everywhere, but I don't
  think that's needed at all, since `pathname` without a leading `./`
  implies the current directory.

- Repurpose the existing `TestIssue398` to also test the `--output`
  flag. Also fix an issue where tests wouldn't work if `GOPATH` has
  multiple entries (e..g `GOPATH=$HOME/go:$HOME/mygocode`).

- Print an error if we can't remove the debug binary on exit instead of
  failing silently. Not strictly related to this PR, but a good change
  to add I think.

* Also warn when delve can't remove the binary in test/trace

I only added that to debug, but good to issue this warning consistently.

These are emitted by C compilers but also by the current development
version of the go compiler with the dwarflocationlists flag.

Either the CPU or the kernel may not support the calls we do when
retrieving floating point registers, this isn't an error we should
propagate.
Also improve the error reporint of pkg/proc/native.fpRegisters.

Fixes #1022

StepBreakpoints are set on CALL instructions, when they are hit we
disassemble the current instruction, figure out the destination address
and set a breakpoint after the prologue of the called function.

In order to disassemble the current instruction we disassemble the area
of memory starting from PC and going to PC+15 (because 15 bytes is the
maximum length of one instruction on AMD64). This means that we won't
just disassemble one instruction but also a few instructions following
it ending with one truncated instruction.

This usually works fine but sometimes the disassembler will panic with
an array out of bounds error when trying to disassemble a truncated
instruction. To avoid this problem this commit changes the funciton
disassemble to take one extra parameter, singleInstr, when singleInstr
is set disassemble will quit after disassembling a single instruction.

If 'iv' is an interface variable with a struct as a concrete value let
'iv.A' evaluate to the access to field 'A' of the concrete value of
'iv'.

Replace the unsafe.Pointer type of the buf field of channels with the
appropriate array type, allow expressions accessing member field of the
channel struct.

Fixes #962

Conditional breakpoints with unmet conditions would cause next and step
to skip the line.

This breakpoint changes the Kind field of proc.Breakpoint from a single
value to a bit field, each breakpoint object can represent
simultaneously a user breakpoint and one internal breakpoint (of which
we have several different kinds).

The breakpoint condition for internal breakpoints is stored in the new
internalCond field of proc.Breakpoint so that it will not conflict with
user specified conditions.

The breakpoint setting code is changed to allow overlapping one
internal breakpoint on a user breakpoint, or a user breakpoint on an
existing internal breakpoint. All other combinations are rejected. The
breakpoint clearing code is changed to clear the UserBreakpoint bit and
only remove the phisical breakpoint if no other bits are set in the
Kind field. ClearInternalBreakpoints does the same thing but clearing
all bits that aren't the UserBreakpoint bit.

Fixes #844

Move some duplicate code, related to breakpoints, that was in both
backends into a single place.
This is in preparation to solve issue #844 (conditional breakpoints
make step and next fail) which will make this common breakpoint code
more complicated.

Since it's just a scratchpad to calculate the new set of registers it
makes more sense to have it as a local variable in Next and
advanceRegs.

Instead of only tracking a few cherrypicked registers in stack.go track
all DWARF registers.

This is needed for cgo code and for the locationlists emitted by go in
1.10:
* The debug_frame sections emitted by C compilers can not be used
  without tracking all registers
* the loclists emitted by go1.10 need all registers of a frame to be
  interpreted.

A thread could terminate between the point when we stop for a
breakpoint and the point where we send a stop signal to all threads, if
this happens setCurrentBreakpoints will fail with an error.

We should tolerate this.

For some reason this happens very frequently when running delve on
processes with the race detector enabed.

Adds test command line flag to compile target fixtures using the -race flag.
Multiple tests will fail because of https://github.com/golang/go/issues/22600
but eventually this should work.

Some linkers will sometimes insert a zero length entry between the last
FDE of a CIE and the next CIE.

1. Use a slice instead of a map to access standard and extended opcodes
   (reduces BenchmarkStateMachine from ~12ms/op to ~7ms/op)

2. Cache StateMachine values for the entry point of functions.

gosymtab and gopclntab only contain informations about go code, linked
C code isn't there, we should use debug_line instead to also cover C.

Updates #935

* string to []rune
* string to []byte
* []rune to string
* []byte to string
* any pointer to uintptr

The string, []rune, []byte conversion pairs aligns this to the go
language.
The pointer -> uintptr conversion pair is symmetric to the uintptr ->
pointer that we already have.

Also lets the user specify any size for byte array types instead of
just the ones already used by the program, this can be used to read
arbitrary memory.

Fixes #548, #867

Make 'next' skip deferred functions unless they are called via a panic.
Call to a deferred function through 'return' are predictable, if the
user wants to step into them 'step' can be used but without this change
there is no way to avoid stepping into them.

Implements #956

On macOS we can also stop when we receive a signal,
propagate this reason upwards to the client.

Also clear internal breakpoints after an unrecovered-panic since they
can not be reached anymore.

Fixes #872

Fixes #959

Fixes #927, #644

debugserver doesn't support qXfer:exec-file:read, and it doesn't return
the executable path in the response to qProcessInfoPID, however we can
find out the executable path by using jGetLoadedDynamicLibrariesInfos.

Implements #596

The compiler a variable 'v' that escapes to the heap with a '&v' entry.
Auto dereference those local variables.

Fixe #871

While we are waiting for the process to exit in native.(*Process).Kill
we could receive queued exception events, those must be continued or
the wait will never finish.

Fixes #940

Always pick a goroutine that we know will have to be resumed before the
program terminates instead of relying on luck.

Fixes #803