I64Shl is lowered to a new turbofan operator, WasmWord64Shl. The new
operator takes 3 inputs, the low-word input, the high-word input, and
the shift, and produces 2 output, the low-word output and the high-word
output.

At the moment I implemented the lowering only for ia32, but I think the
CL is already big enough. I will add the other platforms in separate
CLs.

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/1756863002

Cr-Commit-Position: refs/heads/master@{#34546}

Comparison operators are lowered using to a lexicographic ordering, e.g.
(a,b) <= (c,d) <<>> (a < c) | (a == c) & (b <= d).

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/1729263002

Cr-Commit-Position: refs/heads/master@{#34287}

(a EQ b) is lowered to ((low(a) XOR low(b)) OR (high(a) XOR high(b))) EQ 0

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/1729493002

Cr-Commit-Position: refs/heads/master@{#34249}

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/1723613002

Cr-Commit-Position: refs/heads/master@{#34241}

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/1716243002

Cr-Commit-Position: refs/heads/master@{#34219}

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/1714793003

Cr-Commit-Position: refs/heads/master@{#34213}

I extended the Int64Lowering to lower calls, loads, stores, returns, and
parameters and apply the lowering on both the test function TF graph and
the WasmRunner TF graph.

The lowering of calls also requires an adjustment of the call descriptor.

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/1704033002

Cr-Commit-Position: refs/heads/master@{#34121}

The goal of the Int64Reducer is to replace all int64 nodes in a tf graph
with a set of int32 nodes such that 64 bit tf functions can be executed
on 32 bit platforms. At the moment the Int64Reducer only replaces
Int64Constants, TruncateInt64ToInt32, and Word64And.

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/1655883002

Cr-Commit-Position: refs/heads/master@{#33721}