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Only pass --global-base to the linker if its set to a non-default value #18056

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Only pass --global-base to the linker if its set to a non-default value #18056

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2 changes: 1 addition & 1 deletion tools/building.py
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Original file line number Diff line number Diff line change
Expand Up @@ -225,7 +225,7 @@ def lld_flags_for_executable(external_symbols):
cmd.append('--max-memory=%d' % settings.INITIAL_MEMORY)
elif settings.MAXIMUM_MEMORY != -1:
cmd.append('--max-memory=%d' % settings.MAXIMUM_MEMORY)
if not settings.RELOCATABLE:
if settings.GLOBAL_BASE != 1024 and not settings.RELOCATABLE:
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@kripken kripken Oct 13, 2022

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Is it worth baking in current defaults of wasm-ld here? I worry about them changing. It seems safer to me to keep passing this.

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@sbc100 sbc100 Oct 13, 2022

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Yes, you are probably right there.

I guess part of my intention here is to express that case when the user doesn't care about the global base at all.. which is the normal case.

On the other hand, since you described the low memory optimization that binaryen does I think emscripten does actually care in more cases than I had thought.

I guess what I want here is to say "If the user specified a specific global base, or if emscripten want to run the low memory optimization, then pass an explictic stack base... otherwise we don't care and wasm-ld can choose whatever it wants"

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@kripken kripken Oct 13, 2022

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I see. Yeah, that makes sense. How about having a place that decides whether we use the low-memory optimization, and it sets GLOBAL_BASE if so? (to 1024) And if not it would be null. Then we could avoid passing null to wasm-ld.

cmd.append('--global-base=%s' % settings.GLOBAL_BASE)

return cmd
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