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cc-wrapper: -march= is not allowed on powerpc #205242

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merged 1 commit into from Jan 10, 2023
Merged

cc-wrapper: -march= is not allowed on powerpc #205242

merged 1 commit into from Jan 10, 2023

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ghost
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@ghost ghost commented Dec 9, 2022

Description of changes

Gcc does not allow -march= on PowerPC:

https://gcc.gnu.org/onlinedocs/gcc-12.2.0/gcc/RS_002f6000-and-PowerPC-Options.html#RS_002f6000-and-PowerPC-Options

Instead, -mcpu= should be used to set the minimum instruction set and -mtune= is used to optimize instruction scheduling for a specific processor. Both flags take the same set of valid values, which includes native.

This commit causes isGccArchSupported to return false for PowerPC targets so we never pass an -march= flag, since that will always be rejected by gcc.

Things done
  • Built on platform(s)
    • powerpc64le-linux (full workstation rebuild)
  • Fits CONTRIBUTING.md.

Gcc does not allow `-march=` on PowerPC:

  https://gcc.gnu.org/onlinedocs/gcc-12.2.0/gcc/RS_002f6000-and-PowerPC-Options.html#RS_002f6000-and-PowerPC-Options

Instead, `-mcpu=` should be used to set the minimum instruction set
and `-mtune=` is used to optimize instruction scheduling for a
specific processor.  Both flags take the same set of valid values,
which includes `native`.

This commit causes `isGccArchSupported` to return `false` for PowerPC
targets so we never pass an `-march=` flag, since that will always be
rejected by gcc.
@ghost ghost requested a review from Ericson2314 as a code owner December 9, 2022 04:08
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@Atemu Atemu left a comment

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From what I could find, the premise is true and the diff lgtm.

@Atemu Atemu requested a review from a team December 9, 2022 08:55
@SuperSandro2000
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@ofborg eval

@Atemu Atemu added the 12.approvals: 2 This PR was reviewed and approved by two reputable people label Dec 9, 2022
@ofborg ofborg bot added 10.rebuild-darwin: 0 This PR does not cause any packages to rebuild 10.rebuild-linux: 0 This PR does not cause any packages to rebuild labels Dec 9, 2022
@sternenseemann sternenseemann merged commit dfa3f14 into NixOS:master Jan 10, 2023
@ghost ghost deleted the ccwrapper-powerpc-march branch January 10, 2023 19:50
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3 participants