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SIL: fix Phi.init for arguments in unreachable blocks

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Treat arguments in unreachable blocks like a degenerate phi so we don't consider it a terminator result.

Fixes a compiler crash.
rdar://135336430
This commit is contained in:
Erik Eckstein
2024-09-05 13:12:13 +02:00
parent be9d34482d
commit d4221f4b2a
2 changed files with 34 additions and 4 deletions
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19
SwiftCompilerSources/Sources/SIL/Argument.swift
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@@ -83,11 +83,22 @@ public struct Phi {
// is only included here for compatibility with .sil tests that have
// not been migrated.
public init?(_ value: Value) {
guard let argument = value as? Argument else { return nil }
guard let argument = value as? Argument else {
return nil
}
var preds = argument.parentBlock.predecessors
guard let pred = preds.next() else { return nil }
let term = pred.terminator
guard term is BranchInst || term is CondBranchInst else { return nil }
if let pred = preds.next() {
let term = pred.terminator
guard term is BranchInst || term is CondBranchInst else {
return nil
}
} else {
// No predecessors indicates an unreachable block (except for function arguments).
// Treat this like a degenerate phi so we don't consider it a terminator result.
if argument is FunctionArgument {
return nil
}
}
self.value = argument
}