swift

ca6e7422 - [DebugInfo] Emit distinct DILocation for different inline instances

[DebugInfo] Emit distinct DILocation for different inline instances LLVM seems to determine a variable instance as a combination of DILocalVariable and DILocation. Therefore if multiple llvm.dbg.declare have the same variable/location parameters, they are considered to be referencing the same instance of variable. Swift IRGen emits a set of llvm.dbg.declare calls for every variable instance (with unique SILDebugScope), so it is important that these calls have distinct variable/location parameters. Otherwise their DIExpression may be incorrect when treated as referencing the same variable. For example, if they have a DIExpression with fragments, we will see this as multiple declarations of the same fragment. LLVM detects this and crashes with assertion failure: DwarfExpression.cpp:679: void llvm::DwarfExpression::addFragmentOffset(const llvm::DIExpression *): Assertion `FragmentOffset >= OffsetInBits && "overlapping or duplicate fragments"' failed. The patch resolves #55703. The LIT test (debug_scope_distinct.swift) is the reproducer from that issue.