post-opt: add more test cases for visit_conditional_successors

This commit was initially crafted to fix an issue with post-opt analysis
that came to light in #53613, planning to solve it by
incorporating an augmented CFG directly into the post-opt analysis. But,
with the issue now sorted out by #53739, this commit
shifted focus to just adding test cases.

=== The original commit message ===

post-opt: use augmented post-domtree for `visit_conditional_successors`

This commit fixes the first problem that was found while digging into
#53613. It turns out that the post-domtree constructed
from regular `IRCode` doesn't work for visiting conditional successors
for post-opt analysis in cases like:
```julia
julia> let code = Any[
               # block 1
               GotoIfNot(Argument(2), 3),
               # block 2
               ReturnNode(Argument(3)),
               # block 3 (we should visit this block)
               Expr(:call, throw, "potential throw"),
               ReturnNode(), # unreachable
           ]
           ir = make_ircode(code; slottypes=Any[Any,Bool,Bool])
           visited = BitSet()
           @test !Core.Compiler.visit_conditional_successors(CC.LazyPostDomtree(ir), ir, #=bb=#1) do succ::Int
               push!(visited, succ)
               return false
           end
           @test 2 ∉ visited
           @test 3 ∈ visited
       end
Test Failed at REPL[14]:16
  Expression: 2 ∉ visited
   Evaluated: 2 ∉ BitSet([2])
```

This might mean that we need to fix on the `postdominates` end, but for
now, this commit tries to get around it by using the augmented post
domtree in `visit_conditional_successors`, while also enforcing the
augmented control flow graph (`construct_augmented_cfg`) to have a
single exit node really. Since the augmented post domtree is now
enforced to have a single return, we can keep using the current
`postdominates` to fix the issue.

However, this commit isn't enough to fix the NeuralNetworkReachability
segfault as reported in #53613, and we need to tackle the second issue
reported there too (#53613 (comment)).

base/compiler/optimize.jl

@@ -527,6 +527,8 @@ function any_stmt_may_throw(ir::IRCode, bb::Int)
     return false
 end
 
+visit_conditional_successors(callback, ir::IRCode, bb::Int) = # used for test
+    visit_conditional_successors(callback, LazyPostDomtree(ir), ir, bb)
 function visit_conditional_successors(callback, lazypostdomtree::LazyPostDomtree, ir::IRCode, bb::Int)
     visited = BitSet((bb,))
     worklist = Int[bb]

test/compiler/effects.jl

@@ -1387,3 +1387,13 @@ let; Base.Experimental.@force_compile; func52843(); end
 # https://github.com/JuliaLang/julia/issues/53508
 @test !Core.Compiler.is_consistent(Base.infer_effects(getindex, (UnitRange{Int},Int)))
 @test !Core.Compiler.is_consistent(Base.infer_effects(getindex, (Base.OneTo{Int},Int)))
+
+@noinline f53613() = @assert isdefined(@__MODULE__, :v53613)
+g53613() = f53613()
+@test !Core.Compiler.is_consistent(Base.infer_effects(f53613))
+@test_broken !Core.Compiler.is_consistent(Base.infer_effects(g53613))
+@test_throws AssertionError f53613()
+@test_throws AssertionError g53613()
+global v53613 = nothing
+@test f53613() === nothing
+@test g53613() === nothing

test/compiler/ssair.jl

@@ -233,35 +233,79 @@ let code = Any[
 end
 
 # issue #37919
-let ci = code_lowered(()->@isdefined(_not_def_37919_), ())[1]
+let ci = only(code_lowered(()->@isdefined(_not_def_37919_), ()))
     ir = Core.Compiler.inflate_ir(ci)
     @test Core.Compiler.verify_ir(ir) === nothing
 end
 
 let code = Any[
         # block 1
-        GotoIfNot(Argument(2), 4),
+        GotoIfNot(Argument(2), 4)
         # block 2
-        GotoNode(3),
+        Expr(:call, throw, "potential throw")
+        ReturnNode() # unreachable
         # block 3
-        Expr(:call, throw, "potential throw"),
+        ReturnNode(Argument(3))
+    ]
+    ir = make_ircode(code; slottypes=Any[Any,Bool,Int])
+    visited = BitSet()
+    @test !Core.Compiler.visit_conditional_successors(ir, #=bb=#1) do succ::Int
+        push!(visited, succ)
+        return false
+    end
+    @test 2 ∈ visited
+    @test 3 ∈ visited
+    oc = Core.OpaqueClosure(ir)
+    @test oc(false, 1) == 1
+    @test_throws "potential throw" oc(true, 1)
+end
+
+let code = Any[
+        # block 1
+        GotoIfNot(Argument(2), 3)
+        # block 2
+        ReturnNode(Argument(3))
+        # block 3
+        Expr(:call, throw, "potential throw")
+        ReturnNode() # unreachable
+    ]
+    ir = make_ircode(code; slottypes=Any[Any,Bool,Int])
+    visited = BitSet()
+    @test !Core.Compiler.visit_conditional_successors(ir, #=bb=#1) do succ::Int
+        push!(visited, succ)
+        return false
+    end
+    @test 2 ∈ visited
+    @test 3 ∈ visited
+    oc = Core.OpaqueClosure(ir)
+    @test oc(true, 1) == 1
+    @test_throws "potential throw" oc(false, 1)
+end
+
+let code = Any[
+        # block 1
+        GotoIfNot(Argument(2), 5)
+        # block 2
+        GotoNode(3)
+        # block 3
+        Expr(:call, throw, "potential throw")
+        ReturnNode()
         # block 4
-        Expr(:call, Core.Intrinsics.add_int, Argument(3), Argument(4)),
-        GotoNode(6),
+        Expr(:call, Core.Intrinsics.add_int, Argument(3), Argument(4))
+        GotoNode(7)
         # block 5
-        ReturnNode(SSAValue(4))
+        ReturnNode(SSAValue(5))
     ]
     ir = make_ircode(code; slottypes=Any[Any,Bool,Int,Int])
-    lazypostdomtree = Core.Compiler.LazyPostDomtree(ir)
     visited = BitSet()
-    @test !Core.Compiler.visit_conditional_successors(lazypostdomtree, ir, #=bb=#1) do succ::Int
+    @test !Core.Compiler.visit_conditional_successors(ir, #=bb=#1) do succ::Int
         push!(visited, succ)
         return false
     end
     @test 2 ∈ visited
     @test 3 ∈ visited
-    @test 4 ∉ visited
-    @test 5 ∉ visited
+    @test 4 ∈ visited
+    @test 5 ∈ visited
     oc = Core.OpaqueClosure(ir)
     @test oc(false, 1, 1) == 2
     @test_throws "potential throw" oc(true, 1, 1)