BUG=v8:5294

Change-Id: If45f25aae8de526027b7851cb4efe0ccf4a7c4b1
Reviewed-on: https://chromium-review.googlesource.com/444226
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43388}

With this CL the out-of-line code of TrapIf will call a builtin instead
of doing a direct runtime call, which is cheaper. In the best case, the
out-of-line code now consists of a single call instruction. The builtin
will load the trapID and then call the runtime to throw a trap.

R=titzer@chromium.org, clemensh@chromium.org

Change-Id: I8a75ba09f40236a3d5cbdc17c1317baf0a3c915a
Reviewed-on: https://chromium-review.googlesource.com/445937
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43366}

Instead of placing a runtime call to StackGuard in the compiled wasm
code, we just call the builtin, which is cheaper. By passing Smi::kZero
as context, we save even more code space and avoid embedding the
context in the code.
The WasmStackGuard builtin then calls the new WasmStackGuard runtime
function, which gets the context from the instance attached to the
calling wasm code, and then does the usual StackGuard logic.

For the unity benchmark in asm-wasm mode, generated code size reduces
from 63.0 to 61.6 MB (-2.1%).

R=titzer@chromium.org, ahaas@chromium.org, mstarzinger@chromium.org

Review-Url: https://codereview.chromium.org/2691993004
Cr-Commit-Position: refs/heads/master@{#43277}