[Wasm] Specify the least valid pointer for wasm32 #39300
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WebAssembly doesn't reserve low addresses but without "extra inhabitants" of the pointer representation, runtime performance and memory footprint are worse. So assume that compiler driver uses wasm-ld and --global-base=1024 to reserve low 1KB.
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Hi @rjmccall, would you have a moment to take a look at this PR? |
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I'd personally be happier with 4096 here (same as other Swift 32-bit platforms, minimizes the chance of unexpected dependencies you'll have to track down later). |
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@swift-ci please smoke test |
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@tbkka thanks, that's updated now. Do you think there's anything else to be done here for a review approval? |
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@swift-ci Please test |
tbkka
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May 24, 2022
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Thank you for your review and follow-up! |
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…resses WebAssembly does not have a reserved address space by default, so we need to explicitly reserve low addresses for extra inhabitants for enum types with pointer payloads. swiftlang#39300 added `--global-base` to reserve low data addresses, but we also need to reserve low function addresses with `--table-base` for function pointers because WebAssembly uses a separate address space for function pointers.
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WebAssembly does not have a reserved address space by default, so we need to explicitly reserve low addresses for extra inhabitants for enum types with pointer payloads. swiftlang/swift#39300 added `--global-base` to reserve low data addresses, but we also need to reserve low function addresses with `--table-base` for function pointers because WebAssembly uses a separate address space for function pointers.
kateinoigakukun
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Sep 15, 2025
WebAssembly does not have a reserved address space by default, so we need to explicitly reserve low addresses for extra inhabitants for enum types with pointer payloads. swiftlang/swift#39300 added `--global-base` to reserve low data addresses, but we also need to reserve low function addresses with `--table-base` for function pointers because WebAssembly uses a separate address space for function pointers.
kateinoigakukun
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that referenced
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Sep 15, 2025
…resses WebAssembly does not have a reserved address space by default, so we need to explicitly reserve low addresses for extra inhabitants for enum types with pointer payloads. swiftlang#39300 added `--global-base` to reserve low data addresses, but we also need to reserve low function addresses with `--table-base` for function pointers because WebAssembly uses a separate address space for function pointers.
kateinoigakukun
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to kateinoigakukun/swift-driver
that referenced
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Sep 15, 2025
WebAssembly does not have a reserved address space by default, so we need to explicitly reserve low addresses for extra inhabitants for enum types with pointer payloads. swiftlang/swift#39300 added `--global-base` to reserve low data addresses, but we also need to reserve low function addresses with `--table-base` for function pointers because WebAssembly uses a separate address space for function pointers.
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WebAssembly doesn't reserve low addresses but without "extra inhabitants" of
the pointer representation, runtime performance and memory footprint are
worse. So assume that compiler driver uses wasm-ld and --global-base=1024 to
reserve low 1KB.