Rewrite "select" operand

[alexsokolsky]

I found a bug in one of the webassembly implementations. As a workaround I need to replace certain "select" operands with "if" operands.
Is there a snippet somewhere that does this (assuming the branches contain side effects) ?

[kripken]

Here is code that does the opposite (if => select) that might be useful:

binaryen/src/passes/RemoveUnusedBrs.cpp

Line 1247 in 4f1295a

Select* selectify(If* iff) {

And here is code that turns an or into an if:

binaryen/src/passes/OptimizeInstructions.cpp

Line 3082 in 4f1295a

Expression* conditionalizeExpensiveOnBitwise(Binary* binary) {

[bulocode]

@kripken, both cases - have side effects check, smth like

EffectAnalyzer ifFalse(passOptions, *getModule(), iff->ifFalse);
if (ifFalse.hasSideEffects()) {
    return nullptr;
}

Are there any workarounds, to replace select & side effects with if ?
Maybe it is possible - to skip some side effects - implicitTrap or readsMemory...

[kripken]

That might be possible, and we already ignore traps if trapsNeverHappen mode is enabled, for example. There might be more cases we could do this, but I can't think of any atm.