[NFC] Update readme to discuss tuples rather than push/pop (#2722)

General multivalue and stacky code is now represented using
tuples. Push should never be used and should be removed, and pop
should only be used for exception catch blocks.

1 files changed, 5 insertions, 3 deletions

diff --git a/README.md b/README.md
index ad500a69c..47886f764 100644
--- a/README.md
+++ b/README.md
@@ -69,9 +69,11 @@ There are a few differences between Binaryen IR and the WebAssembly language:
      it can read a wasm text file if it contains only s-expressions.
    * Binaryen uses Stack IR to optimize "stacky" code (that can't be
      represented in structured form).
-   * In rare cases stacky code must be represented in Binaryen IR as well, like
-     popping a value in an exception catch. To support that Binaryen IR has
-     `push` and `pop` instructions.
+   * When stacky code must be represented in Binaryen IR, such as with
+     multivalue instructions and blocks, it is represented with tuple types that
+     do not exist in the WebAssembly language. In addition to multivalue
+     instructions, locals and globals can also have tuple types in Binaryen IR
+     but not in WebAssembly.
  * Types and unreachable code
    * WebAssembly limits block/if/loop types to none and the concrete value types
      (i32, i64, f32, f64). Binaryen IR has an unreachable type, and it allows