[wasm-split] Add an option to skip importing placeholders (#6942)

Wasm-split generally assumes that calls to secondary functions made
before the secondary module has been loaded and instantiated should go
to imported placeholder functions that can be responsible for loading
the secondary module and forwarding the call to the loaded function.
That scheme makes the loading entirely transparent from the
application's point of view, which is not always a good thing. Other
schemes would make it impossible for a secondary function to be called
before the secondary module has been explicitly loaded, in which case
the placeholder functions would never be called. To improve code size
and simplify instantiation under these schemes, add a new
`--no-placeholders` option that skips adding imported placeholder
functions.

1 files changed, 5 insertions, 0 deletions

diff --git a/test/lit/help/wasm-split.test b/test/lit/help/wasm-split.test
index dc521a82f..4fa534e43 100644
--- a/test/lit/help/wasm-split.test
+++ b/test/lit/help/wasm-split.test
@@ -52,6 +52,11 @@
 ;; CHECK-NEXT:   --symbolmap                          [split] Write a symbol map file for each
 ;; CHECK-NEXT:                                        of the output modules.
 ;; CHECK-NEXT:
+;; CHECK-NEXT:   --no-placeholders                    [split] Do not import placeholder
+;; CHECK-NEXT:                                        functions. Calls to secondary functions
+;; CHECK-NEXT:                                        will fail before the secondary module has
+;; CHECK-NEXT:                                        been instantiated.
+;; CHECK-NEXT:
 ;; CHECK-NEXT:   --placeholdermap                     [split] Write a file mapping placeholder
 ;; CHECK-NEXT:                                        indices to the function names.
 ;; CHECK-NEXT: