wasm2js: Sign-extend support (#2949)

The usual "trick" to extend: shift left so the sign bit in the small
integer is now the sign bit in a 32-bit integer, then shift right to
spread that sign bit out and return the lower bits to their
proper place, (x << 24) >> 24.

1 files changed, 43 insertions, 0 deletions

diff --git a/test/wasm2js/sign_ext.2asm.js.opt b/test/wasm2js/sign_ext.2asm.js.opt
new file mode 100644
index 000000000..d24ab0ca4
--- /dev/null
+++ b/test/wasm2js/sign_ext.2asm.js.opt
@@ -0,0 +1,43 @@
+
+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($0_1) {
+  $0_1 = $0_1 | 0;
+  return $0_1 << 24 >> 24;
+ }
+ 
+ function $1($0_1) {
+  $0_1 = $0_1 | 0;
+  return $0_1 << 16 >> 16;
+ }
+ 
+ var FUNCTION_TABLE = [];
+ return {
+  "test8": $0, 
+  "test16": $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 test8 = retasmFunc.test8;
+export var test16 = retasmFunc.test16;