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Erik Eckstein
0f0aa0c17b
These two new invariants eliminate corner cases which caused bugs if optimization didn't handle them. Also, it will significantly simplify lifetime completion. The implementation basically consists of these changes: * add a flag in SILFunction which tells optimization if they need to take care of infinite loops * add a utility to break infinite loops * let all optimizations remove unreachable blocks and break infinite loops if necessary * add verification to check the new SIL invariants The new `breakIfniniteLoops` utility breaks infinite loops in the control flow by inserting an "artificial" loop exit to a new dead-end block with an `unreachable`. It inserts a `cond_br` with a `builtin "infinite_loop_true_condition"`: ``` bb0: br bb1 bb1: br bb1 // back-end branch ``` -> ``` bb0: br bb1 bb1: %1 = builtin "infinite_loop_true_condition"() // always true, but the compiler doesn't know cond_br %1, bb2, bb3 bb2: // new back-end block br bb1 bb3: // new dead-end block unreachable ```
59 lines
1.2 KiB
Plaintext
59 lines
1.2 KiB
Plaintext
// RUN: %target-sil-opt -enable-sil-verify-all %s -simplify-bb-args -sroa-bb-args | %FileCheck %s
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sil_stage canonical
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import Builtin
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import Swift
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import SwiftShims
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enum E {
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case A
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case B
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}
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// Check that we don't crash in simplifyToSelectValue (rdar://problem/20037686)
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// CHECK-LABEL: @test
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sil public @test : $@convention(thin) (Builtin.Int64, @inout E) -> () {
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bb0(%0 : $Builtin.Int64, %x : $*E):
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%1 = integer_literal $Builtin.Int64, 0
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%2 = builtin "cmp_eq_Int64"(%0 : $Builtin.Int64, %1 : $Builtin.Int64) : $Builtin.Int1
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cond_br %2, bb3, bb1
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bb1:
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%4 = enum $E, #E.A!enumelt
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br bb2(%4 : $E)
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bb2(%6 : $E):
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store %6 to %x : $*E
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br bb3
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bb3:
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%8 = tuple ()
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return %8 : $()
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}
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// Verify that we do not crash in argument splitting (rdar://problem/25008398).
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class C {
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@_hasStorage let x: Builtin.Int32
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init()
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}
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struct Pair {
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@_hasStorage let first: C
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@_hasStorage let second: C
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}
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// CHECK-LABEL: @simplify_args_crash
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sil @simplify_args_crash : $@convention(thin) (Pair) -> () {
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bb0(%1 : $Pair):
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// CHECK: bb0
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// CHECK-NEXT: br bb1
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br bb1(%1 : $Pair)
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bb1(%2 : $Pair):
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br bb1(%2 : $Pair)
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}
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