Massive memory growth for -O3, -O4, -Os and -Oz, in ssa-nomerge

Hi. I am planning on applying wasm-opt to my Go project as part of https://github.com/Jacalz/hegelmote/pull/30. The Go WASM files are generally quite big and our toolkit is not super optimised for WASM yet so I wanted to optimise it. As I was interested in seeing which level made the most sense, I aimed to run all of the levels to see how long they take and how they affect the binary size. What I unfortunately found out was that O1 and O2 were the only ones that were usable as -O3, -O4, -Os and -Oz all seem to use memory exponentially until all 32 GB are full. I have attached the file below if you wish to try and reproduce it.

Results:

• Baseline: 37.3 MB
• O1: 35.7 MB, 29.85 s
• O2: 35.7 MB, 32.78 secs
• O3: DNF
• O4: DNF
• Os: DNF
• Oz: DNF

Running:

wasm-opt Hegelmote.wasm --enable-bulk-memory-opt -O3 -o O3.wasm

Potentially related to https://github.com/WebAssembly/binaryen/issues/3646.

Reference file: hegelmote-wasm.zip

Reproduce the memory growth with the attached hegelmote-wasm.zip using the shown wasm-opt command and compare -O1/-O2 with -O3, -O4, -Os, and -Oz. Read the related Binaryen issue 3646 and trace the optimizer entry points reached by these levels; done means the affected optimization levels no longer exhaust system memory on the reference file.