Compatibility with --pie and --experimental-pic wasm-ld flag

[jkelleyrtp]

Motivation

I've implemented WASM hot patching for Rust.

DioxusLabs/dioxus#3797 (comment)

432065352-b81f1a60-b6b2-422d-a536-d9e0bcd75221.mp4

I'd like to fixup the generated patches by running the various transforms (externref being the pricky set) but wasm-bindgen simply refuses to run with WASM linked with the wasm-ld pie and pic flags.

❯ wasm-bindgen --out-dir patch --target web libsimple-web-example-fullstack-patch-1745952796957.wasm
error: invalid offset for segment of function table Global(Id { idx: 2 })

The ifunc table is initialized to a global because it is relocated at runtime.

https://github.com/WebAssembly/tool-conventions/blob/main/DynamicLinking.md

For references this is the set of linker args I'm passing to wasm-ld:

"--fatal-warnings",
"--verbose",
"--import-memory",
"--import-table",
"--growable-table",
"--export-all",
"--export",
"main",
"--allow-undefined",
"--no-demangle",
"--no-entry",
"--pie",
"--no-gc-sections",
"--experimental-pic",

Proposed Solution

wasm-bindgen should be able to work with relocatable ifunc tables.

Alternatives

I can work around this somewhat (using --table-base and --global-base flags and skipping PIE/PIC) but the tooling shouldn't just give up when it sees PIC/PIE code.