The Runtime Theory
HardwareInternalsarchitecture

Trace: From Source Files to a Running Program

Follow the key state changes and boundary checks involved in from source files to a running program.

The Runtime Theory Team8 min read05 steps

layer stack

Hardware

HWHardware
KKernel
RTRuntime
APPApplication
SYSSystem
CLIClient
NETNetwork
TLSCrypto
SRVServer

adjacent altitudes in this subsystem are still being traced

trace spine

  1. 01 Parse and check source
  2. 02 Emit object-level symbols
  3. 03 Resolve references at link time
  4. 04 Map executable segments
  5. 05 Run startup and entry code
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This trace follows the actual state transitions behind the companion From Source Files to a Running Program. It describes a common execution path; implementation details can vary, so keep the contract separate from the mechanism.

Step 1: Parse and check source

A build turns source text and dependencies into an executable representation through distinct stages. A compiler typically parses and checks source, translates it to an intermediate or machine representation, and emits object files. A linker resolves references across those objects and libraries to produce a loadable program.

Step 2: Emit object-level symbols

If module A calls a function defined in module B, A’s object file can contain a symbol reference that the linker resolves. At startup, the operating system maps executable segments, prepares process state, and transfers control to runtime startup code before the application entry point.

When one object refers to a function in another, the linker resolves the symbol before launch; the loader then maps the executable and prepares process state.

At this point, record the state that changed and check the invariant before advancing. If the operation repeats, make clear which values persist and which are recomputed.

Step 4: Map executable segments

Compilation and linking errors indicate different classes of problems: a syntax or type error occurs before object generation, while an unresolved symbol is often discovered at link time. Dynamic linking can defer library resolution to load or runtime, introducing version and search-path concerns.

Step 5: Run startup and entry code

A function declaration is visible to a source file, but the final build reports that its implementation is missing. Identify the likely build stage and two places to investigate.

The trace is complete when the result satisfies the stated contract. Compare this model with the concrete runtime or system you are studying before making a performance claim.

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