[opencl]

Garbage collection isn't really a problem because no CPU architecture supports garbage collection- the compiler is generating code to implement the GC regardless. The issue is that WASM doesn't really resemble real CPUs at all. Basically all modern CPUs are register machines, but WASM is a stack machine.

Say you have the code C=A+B in your program.

The generated assembly for a real machine looks something like this: (R* denote registers and A-C are memory addresses) load A->R1 load B->R2 add R1+R2->R3 store R3->C

WASM looks more like this: push A push B add pop C

This alone makes the approach to code generation and optimization quite different.

WASM does lack some features that you would find in real CPUs, most notably the ability for execution to jump to arbitrary memory locations. They had to work around this to maintain the behavior of goroutines. Functions also live in their own address spaces which necessitates a change to how the program counter works.