gcc: deduplicate top-level expressions #243607
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ghost
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Jul 15, 2023
pkgs/top-level/all-packages.nix
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| else if atLeast "6" then (if stdenv.targetPlatform.isRedox then isl_0_17 else isl_0_14) | ||
| else if atLeast "4.9" then isl_0_11 | ||
| else /* "4.8" */ isl_0_14; |
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The ISL version we are using jumps backward from 0.14 on gcc48 to 0.11 on gcc49, then forward again at gcc6. If gcc49 cannot use isl 0.14 why is gcc48 able to? I doubt this is right, but if it is there should be an explanatory comment, and I found none.
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| else if atLeast "7" then isl_0_17 | ||
| else if atLeast "6" then (if stdenv.targetPlatform.isRedox then isl_0_17 else isl_0_14) |
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gcc6 bumps to isl 0.17 only if compiling for RedoxOS. This probably means that gcc6 is able to use isl 0.17 everywhere. If not, there should have been a comment explaining why RedoxOS is special here.
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| # Build fails on Darwin with clang | ||
| stdenv = if stdenv.isDarwin then gccStdenv else stdenv; |
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gcc49 on Darwin uses gccStdenv because "build fails on Darwin with clang"; surely if that is the case then that is true for gcc48 as well, no?
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| else if atLeast "4.9" then cloog_0_18_0 | ||
| else /* 4.8 */ cloog; |
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gcc49 overrides cloog to v0.18.0, but gcc48 doesn't. Again, very weird, probably somebody meant to override gcc 4.9 and all older versions, not just that one particular version.
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| } // lib.optionalAttrs (atLeast "6" && !(atLeast "9")) { | ||
| # gcc 10 is too strict to cross compile gcc <= 8 | ||
| stdenv = if (stdenv.targetPlatform != stdenv.buildPlatform) && stdenv.cc.isGNU then gcc7Stdenv else stdenv; |
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when cross-compiling, gcc6,7,8 override stdenv to gcc7Stdenv because "gcc 10 is too strict to cross compile gcc <= 8" yet this override was not applied to any other versions of gcc which are "<= 8". It's also odd that gcc7Stdenv is used rather than gcc8Stdenv.
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Jul 17, 2023
This commit deduplicates the copy-pasted gcc mess in pkgs/top-level/all-packages.txt, replacing it with a single expression that branches based on the chosen version. This refactoring has exposed several bizzare behaviors in our historical gcc expressions. These are almost certainly a result of people reaching back and making a change only to the version they care about, and neglecting adjacent versions. These oddities went un-noticed because in copy-paste-duplicated form it is nearly impossible to notice what has happened. When refactored into branch-on-version form, the irregularities jump out at you: 1. The ISL version we are using jumps *backward* from 0.14 on gcc48 to 0.11 on gcc49, then forward again at gcc6. If gcc49 cannot use isl 0.14 why is gcc48 able to? I doubt this is right, but if it is there should be an explanatory comment, and I found none. 2. gcc6 bumps to isl 0.17 only if compiling for RedoxOS. This probably means that gcc6 is able to use isl 0.17 everywhere. If not, there should have been a comment explaining why RedoxOS is special here. 3. gcc49 on Darwin uses gccStdenv because "build fails on Darwin with clang"; surely if that is the case then that is true for gcc48 as well, no? 4. gcc49 overrides cloog to v0.18.0, but gcc48 doesn't. Again, very weird, probably somebody meant to override gcc 4.9 *and all older versions*, not just that one particular version. 5. when cross-compiling, gcc6,7,8 override stdenv to gcc7Stdenv because "gcc 10 is too strict to cross compile gcc <= 8" yet this override was not applied to any other versions of gcc which are "<= 8". It's also odd that gcc7Stdenv is used rather than gcc8Stdenv. The best part about switch-on-version form is that oversights like the above *make the code more verbose* so they stand out. Fixing these likely-bugs will make the code simpler and shorter. In copy-paste-duplicated style the opposite is true: you get shorter code by *forgetting* to apply changes to all the versions that need the change! That's a very perverse incentive. This PR does not attempt to change or fix any of these behaviors. I have confirmed that it does not affect eval (same drv-hash) for all gcc versions on both x86_64-linux and x86_64-darwin.
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Fixed merge conflict. |
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This commit does not affect eval (no drv-hash changes).
Description of changes
This commit deduplicates the copy-pasted gcc mess in
pkgs/top-level/all-packages.txt, replacing it with a single expression that branches based on the chosen version.This exposed several bizzare behaviors in our historical gcc expressions (these bullet points are repeated below alongside the code they refer to):
The ISL version we are using jumps backward from 0.14 on gcc48 to 0.11 on gcc49, then forward again at gcc6. If gcc49 cannot use isl 0.14 why is gcc48 able to? I doubt this is right, but if it is there should be an explanatory comment, and I found none.
gcc6 bumps to isl 0.17 only if compiling for RedoxOS. This probably means that gcc6 is able to use isl 0.17 everywhere. If not, there should have been a comment explaining why RedoxOS is special here.
gcc49 on Darwin uses gccStdenv because "build fails on Darwin with clang"; surely if that is the case then that is true for gcc48 as well, no?
gcc49 overrides cloog to v0.18.0, but gcc48 doesn't. Again, very weird, probably somebody meant to override gcc 4.9 and all older versions, not just that one particular version.
when cross-compiling, gcc6,7,8 override stdenv to gcc7Stdenv because "gcc 10 is too strict to cross compile gcc <= 8" yet this override was not applied to any other versions of gcc which are "<= 8". It's also odd that gcc7Stdenv is used rather than gcc8Stdenv.
The best part about switch-on-version form is that oversights like the above make the code more verbose so they stand out. Fixing these likely-bugs will make the code simpler and shorter. In copy-paste-duplicated style the opposite is true: you get shorter code by forgetting to apply changes to all the versions that need the change! That's a perverse incentive.
This PR does not attempt to change or fix any of these behaviors. I have confirmed that it does not affect eval (same drv-hash) for all gcc versions on both
x86_64-linuxandx86_64-darwin.Things done