We had an llvm_unreachable following a switch on the WasmAddress's type.
However, the type is encoded in a larger 64 bit address, and therefore
it's possible to create an invalid value that doesn't map back on one of
the enum types.
We could try to diagnose that in the wrapper, or treat all invalid types
the same. I took the latter approach because it makes it easier to show
the invalid type after the fact in an error message.
rdar://168314695
This PR implements a register context for Wasm, which uses virtual
registers to resolve Wasm local, globals and stack values. The registers
are used to implement support for `DW_OP_WASM_location` in the DWARF
expression evaluator (#151010). This also adds a more comprehensive
test, showing that we can use this to show local variables.
This patch fixes:
lldb/source/Plugins/Process/wasm/ProcessWasm.cpp:107:25: error:
format specifies type 'unsigned long long' but the argument has type
'lldb::tid_t' (aka 'unsigned long') [-Werror,-Wformat]
Extend support in LLDB for WebAssembly. This PR adds a new Process
plugin (ProcessWasm) that extends ProcessGDBRemote for WebAssembly
targets. It adds support for WebAssembly's memory model with separate
address spaces, and the ability to fetch the call stack from the
WebAssembly runtime.
I have tested this change with the WebAssembly Micro Runtime (WAMR,
https://github.com/bytecodealliance/wasm-micro-runtime) which implements
a GDB debug stub and supports the qWasmCallStack packet.
```
(lldb) process connect --plugin wasm connect://localhost:4567
Process 1 stopped
* thread #1, name = 'nobody', stop reason = trace
frame #0: 0x40000000000001ad
wasm32_args.wasm`main:
-> 0x40000000000001ad <+3>: global.get 0
0x40000000000001b3 <+9>: i32.const 16
0x40000000000001b5 <+11>: i32.sub
0x40000000000001b6 <+12>: local.set 0
(lldb) b add
Breakpoint 1: where = wasm32_args.wasm`add + 28 at test.c:4:12, address = 0x400000000000019c
(lldb) c
Process 1 resuming
Process 1 stopped
* thread #1, name = 'nobody', stop reason = breakpoint 1.1
frame #0: 0x400000000000019c wasm32_args.wasm`add(a=<unavailable>, b=<unavailable>) at test.c:4:12
1 int
2 add(int a, int b)
3 {
-> 4 return a + b;
5 }
6
7 int
(lldb) bt
* thread #1, name = 'nobody', stop reason = breakpoint 1.1
* frame #0: 0x400000000000019c wasm32_args.wasm`add(a=<unavailable>, b=<unavailable>) at test.c:4:12
frame #1: 0x40000000000001e5 wasm32_args.wasm`main at test.c:12:12
frame #2: 0x40000000000001fe wasm32_args.wasm
```
This PR is based on an unmerged patch from Paolo Severini:
https://reviews.llvm.org/D78801. I intentionally stuck to the
foundations to keep this PR small. I have more PRs in the pipeline to
support the other features/packets.
My motivation for supporting Wasm is to support debugging Swift compiled
to WebAssembly:
https://www.swift.org/documentation/articles/wasm-getting-started.html
