mem2reg is performed in an incorrect block order #9771
Description
Aim
I was running into this in the alias graph refactor: for a given function:
acir(inline) fn main f0 {
b0():
v1 = allocate -> &mut Field
store Field 0 at v1
v3 = allocate -> &mut &mut Field
store v1 at v3
jmp b1(Field 0)
b1(v0: Field):
v4 = eq v0, Field 0
jmpif v4 then: b2, else: b3
b2():
v12 = load v3 -> &mut Field
store Field 2 at v12
v14 = add v0, Field 1
jmp b1(v14)
b3():
v5 = load v1 -> Field
v7 = eq v5, Field 2
constrain v5 == Field 2
v8 = load v3 -> &mut Field
v9 = load v3 -> &mut Field
v10 = load v9 -> Field
v11 = eq v10, Field 2
constrain v10 == Field 2
return
}
We iterate in reverse post order which is:
block order = [Id(0), Id(1), Id(3), Id(2)]
Notably, this has us analyzing b3 before its predecessor b2 is finished.
Expected Behavior
Barring loops, we should analyze all blocks only after their predecessor has finished being analyzed
Bug
We do not do this.
To Reproduce
Workaround
None
Workaround Description
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Additional Context
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Project Impact
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Blocker Context
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Nargo Version
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NoirJS Version
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Proving Backend Tooling & Version
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