1749891 - Fix loop phi reduction with loops that throw inside of try blocks

Status: RESOLVED FIXED

(Core :: JavaScript: WebAssembly, defect, P2)

Description

[Ryan Hunt [:rhunt]]

We minimize phi nodes when finishing a loop block. There is some logic for ensuring all redundant phi node uses are updated correctly, but it's missing logic for control flow patches added by throw/call statements inside of try blocks.

One reduced test case discovered from 64MiB photoshop wasm binary.

(func (local i32)
    try
      loop
        call 0
        i32.const 0
        br_if 0
      end
    catch_all
    end
  )

Comment 1

[Ryan Hunt [:rhunt]]

Attachment: Bug 1749891 - wasm: Fix loop phi reduction with loops that throw inside of try blocks. r?lth

We minimize phi nodes when finishing a loop block. There is some
logic for ensuring all redundant phi node uses are updated correctly,
but it's missing logic for control flow patches added by throw/call
statements inside of try blocks

This commit extends the setLoopBackedge() code to fixup redundant
phi nodes that escape via landing pad patches to enclosing try
blocks.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/4f3a057379ab
wasm: Fix loop phi reduction with loops that throw inside of try blocks. r=nbp

Comment 3

[Marian-Vasile Laza]

https://hg.mozilla.org/mozilla-central/rev/4f3a057379ab