In the C++ wasm interpreter, we decode LEB encoded immediates each time
we execute the respective instruction. The whole instruction sequence
was validated before, thus we know that all integers are valid.
This CL refactors several Decoder methods to allow for either checked
or unchecked decoding. In the checked case, an error is set if a check
fails, in the unchecked case, a DCHECK will fail.
This improves performance of the interpreter by 20.5%.
R=ahaas@chromium.org
BUG=v8:5822
Change-Id: If69efd4f6fbe19d84bfc2f4aa000f429a8e22bf5
Reviewed-on: https://chromium-review.googlesource.com/468786
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44406}
Both methods decoded a LEB128 encoded integer, but only consume_leb
incremented the pc pointer accordingly.
This CL implements consume_leb by using checked_read_leb.
It also refactors a few things:
1) It removes error_pt, which was only avaible in checked_read_leb.
2) It renames the error method to errorf, since it receives a format
string. This also avoids a name clash.
3) It implements sign extension directly in checked_read_leb instead of
doing this in the caller.
R=ahaas@chromium.org
BUG=v8:5822
Change-Id: I8058f57418493861e5df26d4949041f6766d5138
Reviewed-on: https://chromium-review.googlesource.com/467150
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44405}
When reading malformed input, the length of variable-length types can be very large. Computing operand length with this and adding it to PC will overflow and screw up decode.
This patch switches to unsigned int for arity and lengths, terminates loop analysis on error, adds overflow checking to BranchTableOperand, and adds a unit test.
Review-Url: https://codereview.chromium.org/2052623003
Cr-Commit-Position: refs/heads/master@{#37301}
Implements:
- WebAssembly object,
- WebAssembly.Module constructor,
- WebAssembly.Instance constructor,
- WebAssembly.compile async method,
- and Module and Instance instance objects.
Also, changes ErrorThrower to support capturing errors in a promise reject.
Since we cannot yet compile without fixing the Wasm memory, and cannot validate a module without compiling, the Module constructor and compile method don't do anything yet but checking that their argument is a suitable BufferSource. Instead of a compiled module, the hidden state of a Module object currently is just that buffer.
BUG=
Review-Url: https://codereview.chromium.org/2084573002
Cr-Commit-Position: refs/heads/master@{#37143}
