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tail call codegen for error returns #690

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andrewrk opened this issue Jan 15, 2018 · 1 comment
Open

tail call codegen for error returns #690

andrewrk opened this issue Jan 15, 2018 · 1 comment
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@andrewrk
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@andrewrk andrewrk commented Jan 15, 2018

for error unions it looks like this:

  tail call fastcc void @__zig_return_error(%StackTrace* %0, i8* blockaddress(@foo, %ReturnError)), !dbg !50
  ret i16 %6, !dbg !50

We could have __zig_return_error take the sret parameter and populate the error value, then return void, so that it can be a tail call.

for pure errors we can pass the error code and return it, and then return it in the parent, another tail call.

Then look at the generated assembly and make sure we're doing tail calls. This is to keep the size of the code generated small for error return tracing. What is a return statement in code without error return tracing can become a jump instruction in code with error return tracing.

@andrewrk andrewrk added this to the 0.3.0 milestone Jan 15, 2018
@andrewrk andrewrk modified the milestones: 0.3.0, 0.4.0 Feb 28, 2018
@andrewrk andrewrk modified the milestones: 0.4.0, 0.5.0 Feb 7, 2019
@andrewrk andrewrk modified the milestones: 0.5.0, 0.6.0 Sep 11, 2019
@andrewrk andrewrk added this to To do in Safety Oct 17, 2019
@andrewrk andrewrk modified the milestones: 0.6.0, 0.7.0 Oct 17, 2019
@luser
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@luser luser commented Mar 27, 2020

@andrewrk andrewrk modified the milestones: 0.7.0, 0.8.0 Oct 9, 2020
@andrewrk andrewrk added the stage2 label Oct 9, 2020
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