optimizer: do not delete statements that may not :terminate (#52999)

Fixes #52991.
Currently this commit marks the test case added in #52954 as `broken`
since it has relied on the behavior of #52991.
I'm planning to add followup changes in a separate commit.

Author: aviatesk

base/compiler/optimize.jl

@@ -48,9 +48,9 @@ const IR_FLAG_INACCESSIBLEMEM_OR_ARGMEM = one(UInt32) << 11
 const NUM_IR_FLAGS = 12 # sync with julia.h
 
 const IR_FLAGS_EFFECTS =
-    IR_FLAG_CONSISTENT | IR_FLAG_EFFECT_FREE | IR_FLAG_NOTHROW | IR_FLAG_NOUB
+    IR_FLAG_CONSISTENT | IR_FLAG_EFFECT_FREE | IR_FLAG_NOTHROW | IR_FLAG_TERMINATES | IR_FLAG_NOUB
 
-const IR_FLAGS_REMOVABLE = IR_FLAG_EFFECT_FREE | IR_FLAG_NOTHROW
+const IR_FLAGS_REMOVABLE = IR_FLAG_EFFECT_FREE | IR_FLAG_NOTHROW | IR_FLAG_TERMINATES
 
 const IR_FLAGS_NEEDS_EA = IR_FLAG_EFIIMO | IR_FLAG_INACCESSIBLEMEM_OR_ARGMEM
 
@@ -69,6 +69,9 @@ function flags_for_effects(effects::Effects)
     if is_nothrow(effects)
         flags |= IR_FLAG_NOTHROW
     end
+    if is_terminates(effects)
+        flags |= IR_FLAG_TERMINATES
+    end
     if is_inaccessiblemem_or_argmemonly(effects)
         flags |= IR_FLAG_INACCESSIBLEMEM_OR_ARGMEM
     end
@@ -331,7 +334,8 @@ function stmt_effect_flags(𝕃ₒ::AbstractLattice, @nospecialize(stmt), @nospe
             consistent = is_consistent(effects)
             effect_free = is_effect_free(effects)
             nothrow = is_nothrow(effects)
-            removable = effect_free & nothrow
+            terminates = is_terminates(effects)
+            removable = effect_free & nothrow & terminates
             return (consistent, removable, nothrow)
         elseif head === :new
             return new_expr_effect_flags(𝕃ₒ, args, src)
@@ -342,7 +346,8 @@ function stmt_effect_flags(𝕃ₒ::AbstractLattice, @nospecialize(stmt), @nospe
             consistent = is_consistent(effects)
             effect_free = is_effect_free(effects)
             nothrow = is_nothrow(effects)
-            removable = effect_free & nothrow
+            terminates = is_terminates(effects)
+            removable = effect_free & nothrow & terminates
             return (consistent, removable, nothrow)
         elseif head === :new_opaque_closure
             length(args) < 4 && return (false, false, false)

base/dict.jl

@@ -868,34 +868,25 @@ struct PersistentDict{K,V} <: AbstractDict{K,V}
     @noinline function KeyValue.set(::Type{PersistentDict{K, V}}, ::Nothing, key, val) where {K, V}
         new{K, V}(HAMT.HAMT{K, V}(key => val))
     end
-    @noinline @Base.assume_effects :effect_free function KeyValue.set(dict::PersistentDict{K, V}, key, val) where {K, V}
+    @noinline Base.@assume_effects :effect_free :terminates_globally KeyValue.set(
+        dict::PersistentDict{K, V}, key, val) where {K, V} = @inline _keyvalueset(dict, key, val)
+    @noinline Base.@assume_effects :nothrow :effect_free :terminates_globally KeyValue.set(
+        dict::PersistentDict{K, V}, key::K, val::V) where {K, V} = @inline _keyvalueset(dict, key, val)
+    global function _keyvalueset(dict::PersistentDict{K, V}, key, val) where {K, V}
         trie = dict.trie
         h = HAMT.HashState(key)
-        found, present, trie, i, bi, top, hs = HAMT.path(trie, key, h, #=persistent=# true)
+        found, present, trie, i, bi, top, hs = HAMT.path(trie, key, h, #=persistent=#true)
         HAMT.insert!(found, present, trie, i, bi, hs, val)
         return new{K, V}(top)
     end
-    @noinline @Base.assume_effects :nothrow :effect_free function KeyValue.set(dict::PersistentDict{K, V}, key::K, val::V) where {K, V}
+    @noinline Base.@assume_effects :effect_free :terminates_globally KeyValue.set(
+        dict::PersistentDict{K, V}, key) where {K, V} = @inline _keyvalueset(dict, key)
+    @noinline Base.@assume_effects :nothrow :effect_free :terminates_globally KeyValue.set(
+        dict::PersistentDict{K, V}, key::K) where {K, V} = @inline _keyvalueset(dict, key)
+    global function _keyvalueset(dict::PersistentDict{K, V}, key) where {K, V}
         trie = dict.trie
         h = HAMT.HashState(key)
-        found, present, trie, i, bi, top, hs = HAMT.path(trie, key, h, #=persistent=# true)
-        HAMT.insert!(found, present, trie, i, bi, hs, val)
-        return new{K, V}(top)
-    end
-    @noinline @Base.assume_effects :effect_free function KeyValue.set(dict::PersistentDict{K, V}, key) where {K, V}
-        trie = dict.trie
-        h = HAMT.HashState(key)
-        found, present, trie, i, bi, top, _ = HAMT.path(trie, key, h, #=persistent=# true)
-        if found && present
-            deleteat!(trie.data, i)
-            HAMT.unset!(trie, bi)
-        end
-        return new{K, V}(top)
-    end
-    @noinline @Base.assume_effects :nothrow :effect_free function KeyValue.set(dict::PersistentDict{K, V}, key::K) where {K, V}
-        trie = dict.trie
-        h = HAMT.HashState(key)
-        found, present, trie, i, bi, top, _ = HAMT.path(trie, key, h, #=persistent=# true)
+        found, present, trie, i, bi, top, _ = HAMT.path(trie, key, h, #=persistent=#true)
         if found && present
             deleteat!(trie.data, i)
             HAMT.unset!(trie, bi)

test/compiler/irpasses.jl

@@ -1836,3 +1836,48 @@ let code = Any[
     @test made_changes
     @test (ir[Core.SSAValue(length(ir.stmts))][:flag] & Core.Compiler.IR_FLAG_REFINED) != 0
 end
+
+# JuliaLang/julia#52991: statements that may not :terminate should not be deleted
+@noinline Base.@assume_effects :effect_free :nothrow function issue52991(n)
+    local s = 0
+    try
+        while true
+            yield()
+            if n - rand(1:10) > 0
+                s += 1
+            else
+                break
+            end
+        end
+    catch
+    end
+    return s
+end
+@test !Core.Compiler.is_removable_if_unused(Base.infer_effects(issue52991, (Int,)))
+let src = code_typed1((Int,)) do x
+        issue52991(x)
+        nothing
+    end
+    @test count(isinvoke(:issue52991), src.code) == 1
+end
+let t = @async begin
+        issue52991(11) # this call never terminates
+        nothing
+    end
+    sleep(1)
+    if istaskdone(t)
+        ok = false
+    else
+        ok = true
+        schedule(t, InterruptException(); error=true)
+    end
+    @test ok
+end
+
+# JuliaLang/julia47664
+@test !fully_eliminated() do
+    any(isone, Iterators.repeated(0))
+end
+@test !fully_eliminated() do
+    all(iszero, Iterators.repeated(0))
+end