miss-optimization for continuous add

[HerrCai0907]

These assemblyscript code

 (func $assembly/index/_start (result i32)
  global.get $assembly/index/a0
  global.get $assembly/index/a1
  i32.add
  global.get $assembly/index/a2
  i32.add
  global.get $assembly/index/a3
  i32.add
  global.get $assembly/index/a4
  i32.add
  global.get $assembly/index/a5
  i32.add
  global.get $assembly/index/a6
  i32.add
  return
 )

will be optimized to

 (func $assembly/index/_start (result i32)
  global.get $assembly/index/a6
  global.get $assembly/index/a5
  global.get $assembly/index/a4
  global.get $assembly/index/a3
  global.get $assembly/index/a2
  global.get $assembly/index/a0
  global.get $assembly/index/a1
  i32.add
  i32.add
  i32.add
  i32.add
  i32.add
  i32.add
 )

Is there any benefit to exchange the operand of i32.add. the optimized version looks like cause higher register pressure for JIT / AOT wasm runtime.

[kripken]

See a related previous discussion here:

#5088 (comment)

Over there, we did not get a clear answer from VM people that one or the other order was better, so we did not change anything. But it may be worth revisiting this. If we have benchmarks that show another order is better, we can flip it.

[tlively]

See also llvm/llvm-project#98631 and llvm/llvm-project#97283 for discussions of a case where preferring a shallower stack has significant performance benefits.