Joseph Ferano
1829cd43b6
The %handler, %restart, %fninfo and %flanframe shapes were written twice: as LLVM type strings in emit.ml and as hand-computed byte offsets in x86.ml, with the two %fninfo initialisers spelled a third and fourth time. Emit.Rt now holds one field list per struct and derives all four — the type string and the getelementptr index for LLVM, the offset and the size for x86, and the initialiser for both. The derived numbers were checked against every old constant before the call sites moved. The flan. prefixes were spelled in four files, including both backends hand-writing "flan." ^ name for a DWARF linkage name instead of calling their own helper. Mangle now holds them unquoted; each backend adds its own sigil. The ABI markers stay apart on purpose: flan.abi.llvm and flan.abi.x86 differing is what makes the loader refuse a crossed pair. The float-to-integer cast bounds and the division-check elision policy are Emit.cast_range and Emit.div_checks. The second is a language decision and had been byte-identical in both files; the first had drifted cosmetically. emit and emit --x86 output for all 166 test/programs, at -O0 release, --dev, --debug and --dev --debug, stdout and stderr, is byte-identical to the pre-change compiler.
43 lines
2.1 KiB
OCaml
43 lines
2.1 KiB
OCaml
(* The symbol names a Flan build puts into an object, spelled once.
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Both backends emit the same names — that is not a nicety, it is the link:
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an [--x86] host and a redefinition module built by LLVM bind against each
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other, so [@"flan.cell.<n>"] has to be byte-for-byte the same string on
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both sides or the dlopen fails and the piece served nothing. The macro
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loader and the daemon's disassembler look up the same names from outside
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the backends entirely.
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So the prefixes live here, unquoted and without a sigil. Quoting is each
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backend's own — LLVM writes [@"..."], the assembler writes ["..."] — and a
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Flan name holds -, ?, > and /, which is why every emitted name is quoted
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at all. This module only decides *which string* is quoted.
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Not here: the ABI marker. [Emit.abi_marker] is ["flan.abi.llvm"] and
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[X86.abi_marker] is ["flan.abi.x86"], and the two must stay distinct —
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a crossed pair is refused at [dlopen] precisely because the marker one
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image defines is not the one the other references. Sharing that string
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would delete the mechanism. *)
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(* The prefix itself. It keeps the Flan [main] from colliding with C's, and
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it is what makes every Flan symbol recognisable in a disassembly. *)
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let prefix = "flan."
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(* A function or a global. One namespace, because the language has one: a
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[defn] and a [defvar] cannot share a name, so nothing here has to keep
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them apart. The compiler's own names go through this too — [.init-globals]
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and [.init-data] start with a dot no reader token can produce. *)
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let sym n = prefix ^ n
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(* A dev build's indirection cell: a mutable global holding the address of the
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function that is currently this name's body. *)
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let cell n = prefix ^ "cell." ^ n
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(* The two module-local caches a name the host was never built with is reached
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through — one for a function, one for a global. *)
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let cellptr n = prefix ^ "cellp." ^ n
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let globalptr n = prefix ^ "gp." ^ n
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(* A compiled macro's entry point, which the expander dlsyms by this name out
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of the module [Build.macro_module] wrote. *)
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let macro n = prefix ^ "macro." ^ n
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