wasm2js: coerce function pointer indexes (#2979)

We emit FUNCTION_TABLE[ptr], where FUNCTION_TABLE is a JS
array. That is a rare case where true is handled differently than 1
(a typed array or an add would cast, etc.), so we must explicitly cast
there.

Fixes an issue that existed before, but became a problem due to
#2869 which optimized some selects into a form that emitted a true
or a false, and if that was a function pointer, it could be bad, see

https://app.circleci.com/pipelines/github/emscripten-core/emscripten/6699/workflows/0c4da49c-75d0-4b0a-8fac-686a8330a3fe/jobs/336520

The new test/wasm2js/indirect-select.2asm.js.opt output shows
what happened there.

Verified as passing emscripten's wasm2js1 wasm2js2 test suites.

1 files changed, 43 insertions, 0 deletions

diff --git a/test/wasm2js/indirect-select.2asm.js b/test/wasm2js/indirect-select.2asm.js
new file mode 100644
index 000000000..d190bb082
--- /dev/null
+++ b/test/wasm2js/indirect-select.2asm.js
@@ -0,0 +1,43 @@
+import { FUNCTION_TABLE } from 'env';
+
+function asmFunc(global, env, buffer) {
+ var HEAP8 = new global.Int8Array(buffer);
+ var HEAP16 = new global.Int16Array(buffer);
+ var HEAP32 = new global.Int32Array(buffer);
+ var HEAPU8 = new global.Uint8Array(buffer);
+ var HEAPU16 = new global.Uint16Array(buffer);
+ var HEAPU32 = new global.Uint32Array(buffer);
+ var HEAPF32 = new global.Float32Array(buffer);
+ var HEAPF64 = new global.Float64Array(buffer);
+ var Math_imul = global.Math.imul;
+ var Math_fround = global.Math.fround;
+ var Math_abs = global.Math.abs;
+ var Math_clz32 = global.Math.clz32;
+ var Math_min = global.Math.min;
+ var Math_max = global.Math.max;
+ var Math_floor = global.Math.floor;
+ var Math_ceil = global.Math.ceil;
+ var Math_sqrt = global.Math.sqrt;
+ var abort = env.abort;
+ var nan = global.NaN;
+ var infinity = global.Infinity;
+ function $0(x) {
+  x = x | 0;
+  return FUNCTION_TABLE[(x ? 1 : 0) | 0]() | 0 | 0;
+ }
+ 
+ function $1(x) {
+  x = x | 0;
+  return FUNCTION_TABLE[(x ? 0 : 1) | 0]() | 0 | 0;
+ }
+ 
+ return {
+  "foo_true": $0, 
+  "foo_false": $1
+ };
+}
+
+var memasmFunc = new ArrayBuffer(65536);
+var retasmFunc = asmFunc({Math,Int8Array,Uint8Array,Int16Array,Uint16Array,Int32Array,Uint32Array,Float32Array,Float64Array,NaN,Infinity}, {abort:function() { throw new Error('abort'); }},memasmFunc);
+export var foo_true = retasmFunc.foo_true;
+export var foo_false = retasmFunc.foo_false;