From: Daniel Golle <daniel@makrotopia.org>
Subject: [PATCH] JavaScriptCore: stub IPInt call trampoline labels on unsupported archs

InPlaceInterpreter is the WebAssembly in-place interpreter (IPInt).
Its real implementation in InPlaceInterpreter64.asm and
InPlaceInterpreter32_64.asm is gated on a small allow-list of
architectures (ARM64/ARM64E/X86_64/ARMv7); every other CPU falls into
the catch-all 'else' branch of InPlaceInterpreter.asm, which only
emits unimplementedInstruction() stubs for the IPInt opcodes.

LowLevelInterpreter.asm, however, unconditionally takes the address
of nine IPInt call-sequence labels:

  _wasm_trampoline_wasm_ipint_{call,tail_call}[_wide16][_wide32]
  _wasm_ipint_call_return_location[_wide16][_wide32]

so on a CPU where WEBASSEMBLY is enabled but the real IPInt is not
(e.g. RISCV64) the link fails:

  mold: error: undefined symbol: .Lwasm_trampoline_wasm_ipint_tail_call
  ...

LowLevelInterpreter.asm itself already emits crash() stubs for the
same nine labels in its !WEBASSEMBLY branch. Mirror that here so the
labels also exist when WEBASSEMBLY is on but the architecture has no
IPInt - they trap if ever reached.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
--- a/Source/JavaScriptCore/llint/InPlaceInterpreter.asm
+++ b/Source/JavaScriptCore/llint/InPlaceInterpreter.asm
@@ -2177,5 +2177,21 @@ unimplementedInstruction(_i32_atomic_rmw
 unimplementedInstruction(_i64_atomic_rmw8_cmpxchg_u)
 unimplementedInstruction(_i64_atomic_rmw16_cmpxchg_u)
 unimplementedInstruction(_i64_atomic_rmw32_cmpxchg_u)
+
+# LowLevelInterpreter.asm captures the addresses of these labels via
+# 'lla' / equivalent for the IPInt call sequence, so they have to exist
+# at link time on architectures that enable WEBASSEMBLY but have no
+# IPInt implementation. They should never be reached at run time.
+_wasm_trampoline_wasm_ipint_call:
+_wasm_trampoline_wasm_ipint_call_wide16:
+_wasm_trampoline_wasm_ipint_call_wide32:
+_wasm_trampoline_wasm_ipint_tail_call:
+_wasm_trampoline_wasm_ipint_tail_call_wide16:
+_wasm_trampoline_wasm_ipint_tail_call_wide32:
+
+_wasm_ipint_call_return_location:
+_wasm_ipint_call_return_location_wide16:
+_wasm_ipint_call_return_location_wide32:
+    crash()
 end