-Zvirtual-function-elimination miscompiles simple hello world program if other optimizations are turned on

[matthiaskrgr]

cargo new foo
cd foo
rustc  -Clto  -Cembed-bitcode=yes -Zvirtual-function-elimination src/main.rs 
./main # this works
> Hello, world!
rustc  -Clto  -Cembed-bitcode=yes -Zvirtual-function-elimination src/main.rs -Copt-level=1
./main
> [1]    2203089 segmentation fault (core dumped)  ./main

cc #96285

rustc 1.63.0-nightly (389352c4b 2022-06-15)
binary: rustc
commit-hash: 389352c4bbd56024eefd1566e06dcba04d223f92
commit-date: 2022-06-15
host: x86_64-unknown-linux-gnu
release: 1.63.0-nightly
LLVM version: 14.0.5

[Luv-Ray]

A possible reason:
lang_start_internal in std is compiled without -Zvirtual-function-elimination, and it doesn't use llvm.type.checked.load to load the vtable of the closure, causing LLVM not to realize the usage of the closure, thus miscompiling the code.

rust/library/std/src/rt.rs

Lines 117 to 125 in d14c1c7

	// To reduce the generated code of the new `lang_start`, this function is doing
	// the real work.
	#[cfg(not(test))]
	fn lang_start_internal(
	main: &(dyn Fn() -> i32 + Sync + crate::panic::RefUnwindSafe),
	argc: isize,
	argv: *const *const u8,
	sigpipe: u8,
	) -> Result<isize, !> {