Lift constructor field initializers ahead of the base call to the field declaration#614
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…ld declaration C# emits field initializers before the base constructor call, so a `this.field = value` store the IL places before the chain call is a field initializer — not a body assignment. The printer rendered it as a body statement, which recompiles to AFTER the base call: an opcode-order diff (the two remaining `.ctor` compile-back docket items, `CfgSampleClass::.ctor` spelling `_shadowed = 1;` and `LockFixtureSamples::.ctor` spelling `_root = new object();`). Generalize the constructor-prologue detection: scan the entry block for the base/this `.ctor` chain call; if every statement before it is a qualifying field-initializer store, lift each to the field declaration (new `DecompilerResult.FieldInitializers`) and let the existing chain lift fire on the call. The compile-back harness threads the initializers through to the target type's field declarations. Soundness: a store only qualifies when its receiver is the under-construction `this` (ldarg.0) AND its value references no place — no `this`, parameter, local, or stack-slot load (`ReferencesPlace`). That is exactly C#'s field-initializer legality rule (initializers cannot read the instance or constructor parameters), so a lifted store is always legal where it lands. Detection requires the whole pre-chain prologue to be such stores, matching the compiler's prologue shape exactly; anything else bails and keeps the current body rendering. Constants, `new T()`, and static reads qualify; a field init that reads a parameter does not and stays in the body. Compile-back fixture exact 151 -> 153 (+2), docket 13 -> 11 (-2), recompile-fail unchanged (527; System.Linq unchanged 395). Decompiler tests 432 -> 434. Pinned `CfgSampleClass::.ctor` exact in the gate. Found via #604. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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What
C# emits field initializers before the base constructor call, so a
this.field = valuestore the IL places before the chain call is a field initializer, not a body assignment. The printer rendered it as a body statement, which recompiles to after the base call — an opcode-order diff. These were the two remaining.ctorcompile-back docket items:CfgSampleClass::.ctor(int _shadowed = 1;)LockFixtureSamples::.ctor(readonly object _root = new();)How
Generalize the constructor-prologue detection in
CSharpPrinter: scan the entry block for the base/this.ctorchain call; if every statement before it is a qualifying field-initializer store, lift each to the field declaration (newDecompilerResult.FieldInitializers) and let the existing chain lift fire on the call. The compile-back harness threads the initializers through to the target type's field declarations.Soundness
A store only qualifies when its receiver is the under-construction
this(ldarg.0) and its value references no place — nothis, parameter, local, or stack-slot load (ReferencesPlace). That is exactly C#'s field-initializer legality rule (initializers cannot read the instance or constructor parameters), so a lifted store is always legal where it lands. Detection requires the whole pre-chain prologue to be such stores, matching the compiler's prologue shape exactly; anything else bails and keeps the current body rendering. Constants,new T(), and static reads qualify; a field init that reads a parameter does not and stays in the body.Numbers
CfgSampleClass::.ctoropcode-exact in the compile-back gate.Found via the #604
--compile-backoracle. Companion to #612.