[llvm] [wasm] Disallow tail calls when passing structs on the stack (PR #124443)

[Timothy Herchen via llvm-commits]

anematode wrote:

This test fails:

```
declare i32 @quux(ptr byval(i32))
define i32 @mismatched_byval(ptr %x) {
; CHECK-LABEL: mismatched_byval:
; CHECK:         .functype mismatched_byval (i32) -> (i32)
; CHECK-NEXT:  # %bb.0:
; CHECK-NEXT:    global.get $push1=, __stack_pointer
; CHECK-NEXT:    i32.const $push2=, 16
; CHECK-NEXT:    i32.sub $push8=, $pop1, $pop2
; CHECK-NEXT:    local.tee $push7=, $1=, $pop8
; CHECK-NEXT:    global.set __stack_pointer, $pop7
; CHECK-NEXT:    i32.load $push0=, 0($0)
; CHECK-NEXT:    i32.store 12($1), $pop0
; CHECK-NEXT:    i32.const $push3=, 16
; CHECK-NEXT:    i32.add $push4=, $1, $pop3
; CHECK-NEXT:    global.set __stack_pointer, $pop4
; CHECK-NEXT:    i32.const $push5=, 12
; CHECK-NEXT:    i32.add $push6=, $1, $pop5
; CHECK-NEXT:    return_call quux, $pop6
  %v = tail call i32 @quux(ptr byval(i32) %x)
  ret i32 %v
}
```

but it's not clear to me that the test is compiled correctly in the first place. Isn't this calling quux with a pointer to (sp - 4)?

https://github.com/llvm/llvm-project/pull/124443