cleanup: remove support for 3DNow! cpu features #127864

durin42 · 2024-07-17T14:12:25Z

In llvm/llvm-project@f0eb558 all support for 3DNow! intrinsics and instructions were removed. Per the commit message there, only AMD chips between 1998 and 2011 or so actually supported these instructions, and they were effectively replaced by SSE which was available on many more chips. I'd be very surprised if anyone had ever used these from Rust.

@rustbot label: +llvm-main

rustbot · 2024-07-17T14:12:33Z

r? @wesleywiser

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rustbot · 2024-07-17T14:12:34Z

These commits modify compiler targets.
(See the Target Tier Policy.)

Some changes occurred in compiler/rustc_codegen_gcc

cc @antoyo, @GuillaumeGomez

mati865 · 2024-07-17T14:45:15Z

I think you are missing "were removed" or something like that in the first sentence of the description (and commit message).

durin42 · 2024-07-17T14:47:40Z

I think you are missing "were removed" or something like that in the first sentence of the description (and commit message).

whoops, good catch. Thanks!

antoyo · 2024-07-17T14:56:10Z

compiler/rustc_codegen_gcc/src/intrinsic/archs.rs

@@ -7210,29 +7210,6 @@ match name {
    "llvm.ve.vl.xorm.MMM" => "__builtin_ve_vl_xorm_MMM",
    "llvm.ve.vl.xorm.mmm" => "__builtin_ve_vl_xorm_mmm",
    // x86
-    "llvm.x86.3dnow.pavgusb" => "__builtin_ia32_pavgusb",


This file is auto-generated, so it doesn't make sense to remove these.

Shucks, just noticed it's in the GCC backend too. I'll undo that.

compiler-errors · 2024-07-17T15:42:33Z

You should squash this so the commit history still doesn't touch an autogenerated file (twice)

In llvm/llvm-project@f0eb558 all support for 3DNow! intrinsics and instructions were removed. Per the commit message there, only AMD chips between 1998 and 2011 or so actually supported these instructions, and they were effectively replaced by SSE which was available on many more chips. I'd be very surprised if anyone had ever used these from Rust.

nikic · 2024-07-18T08:02:06Z

@bors r+ rollup

bors · 2024-07-18T08:02:08Z

📌 Commit 72e2255 has been approved by nikic

It is now in the queue for this repository.

nikic · 2024-07-18T08:12:43Z

@rustbot ping rfl

I think rfl will need to also adjust this here: https://github.com/Rust-for-Linux/linux/blob/b1263411112305acf2af728728591465becb45b0/scripts/generate_rust_target.rs#L165 Or alternatively tell us that adding -3dnow is really necessary on older LLVM versions, in which case we'll have to add some emulation. I don't think it's needed because LLVM should not generate 3dnow instructions unless specifically asked to, using intrinsics that Rust does not provide in the first place.

Rollup of 7 pull requests Successful merges: - rust-lang#127491 (Migrate 8 very similar FFI `run-make` tests to rmake) - rust-lang#127687 (Const-to-pattern-to-MIR cleanup) - rust-lang#127822 (Migrate `issue-85401-static-mir`, `missing-crate-dependency` and `unstable-flag-required` `run-make` tests to rmake) - rust-lang#127842 (Remove `TrailingToken`.) - rust-lang#127864 (cleanup: remove support for 3DNow! cpu features) - rust-lang#127899 (Mark myself as on leave) - rust-lang#127901 (Add missing GHA group for building `llvm-bitcode-linker`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#127864 - durin42:farewell-3dnow, r=nikic cleanup: remove support for 3DNow! cpu features In llvm/llvm-project@f0eb558 all support for 3DNow! intrinsics and instructions were removed. Per the commit message there, only AMD chips between 1998 and 2011 or so actually supported these instructions, and they were effectively replaced by SSE which was available on many more chips. I'd be very surprised if anyone had ever used these from Rust. `@rustbot` label: +llvm-main

LLVM 19 is dropping support for 3DNow! in commit f0eb5587ceeb ("Remove support for 3DNow!, both intrinsics and builtins. (#96246)"): Remove support for 3DNow!, both intrinsics and builtins. (#96246) This set of instructions was only supported by AMD chips starting in the K6-2 (introduced 1998), and before the "Bulldozer" family (2011). They were never much used, as they were effectively superseded by the more-widely-implemented SSE (first implemented on the AMD side in Athlon XP in 2001). This is being done as a predecessor towards general removal of MMX register usage. Since there is almost no usage of the 3DNow! intrinsics, and no modern hardware even implements them, simple removal seems like the best option. Thus we should avoid passing these to the backend, since otherwise we get a diagnostic about it: '-3dnow' is not a recognized feature for this target (ignoring feature) '-3dnowa' is not a recognized feature for this target (ignoring feature) We could try to disable them only up to LLVM 19 (not the C side one, but the one used by `rustc`, which may be built with a range of LLVMs). However, to avoid more complexity, we can likely just remove them altogether. According to Nikita [2]: > I don't think it's needed because LLVM should not generate 3dnow instructions unless specifically asked to, using intrinsics that Rust does not provide in the first place. Thus do so, like Rust did for one of their builtin targets [3]. For those curious: Clang will warn only about trying to enable them (`-m3dnow{,a}`), but not about disabling them (`-mno-3dnow{,a}`), so there is no change needed there. Cc: Nikita Popov <github@npopov.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: x86@kernel.org Link: llvm/llvm-project@f0eb558 [1] Link: rust-lang/rust#127864 (comment) [2] Link: rust-lang/rust#127864 [3] Closes: Rust-for-Linux#1094 Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

LLVM 19 is dropping support for 3DNow! in commit f0eb5587ceeb ("Remove support for 3DNow!, both intrinsics and builtins. (#96246)"): Remove support for 3DNow!, both intrinsics and builtins. (#96246) This set of instructions was only supported by AMD chips starting in the K6-2 (introduced 1998), and before the "Bulldozer" family (2011). They were never much used, as they were effectively superseded by the more-widely-implemented SSE (first implemented on the AMD side in Athlon XP in 2001). This is being done as a predecessor towards general removal of MMX register usage. Since there is almost no usage of the 3DNow! intrinsics, and no modern hardware even implements them, simple removal seems like the best option. Thus we should avoid passing these to the backend, since otherwise we get a diagnostic about it: '-3dnow' is not a recognized feature for this target (ignoring feature) '-3dnowa' is not a recognized feature for this target (ignoring feature) We could try to disable them only up to LLVM 19 (not the C side one, but the one used by `rustc`, which may be built with a range of LLVMs). However, to avoid more complexity, we can likely just remove them altogether. According to Nikita [2]: > I don't think it's needed because LLVM should not generate 3dnow instructions unless specifically asked to, using intrinsics that Rust does not provide in the first place. Thus do so, like Rust did for one of their builtin targets [3]. For those curious: Clang will warn only about trying to enable them (`-m3dnow{,a}`), but not about disabling them (`-mno-3dnow{,a}`), so there is no change needed there. Cc: Nikita Popov <github@npopov.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: x86@kernel.org Link: llvm/llvm-project@f0eb558 [1] Link: rust-lang/rust#127864 (comment) [2] Link: rust-lang/rust#127864 [3] Closes: #1094 Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Tested-by: Benno Lossin <benno.lossin@proton.me> Link: https://lore.kernel.org/r/20240806144558.114461-1-ojeda@kernel.org

LLVM 19 is dropping support for 3DNow! in commit f0eb5587ceeb ("Remove support for 3DNow!, both intrinsics and builtins. (#96246)"): Remove support for 3DNow!, both intrinsics and builtins. (#96246) This set of instructions was only supported by AMD chips starting in the K6-2 (introduced 1998), and before the "Bulldozer" family (2011). They were never much used, as they were effectively superseded by the more-widely-implemented SSE (first implemented on the AMD side in Athlon XP in 2001). This is being done as a predecessor towards general removal of MMX register usage. Since there is almost no usage of the 3DNow! intrinsics, and no modern hardware even implements them, simple removal seems like the best option. Thus we should avoid passing these to the backend, since otherwise we get a diagnostic about it: '-3dnow' is not a recognized feature for this target (ignoring feature) '-3dnowa' is not a recognized feature for this target (ignoring feature) We could try to disable them only up to LLVM 19 (not the C side one, but the one used by `rustc`, which may be built with a range of LLVMs). However, to avoid more complexity, we can likely just remove them altogether. According to Nikita [2]: > I don't think it's needed because LLVM should not generate 3dnow > instructions unless specifically asked to, using intrinsics that > Rust does not provide in the first place. Thus do so, like Rust did for one of their builtin targets [3]. For those curious: Clang will warn only about trying to enable them (`-m3dnow{,a}`), but not about disabling them (`-mno-3dnow{,a}`), so there is no change needed there. Cc: Nikita Popov <github@npopov.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: x86@kernel.org Link: llvm/llvm-project@f0eb558 [1] Link: rust-lang/rust#127864 (comment) [2] Link: rust-lang/rust#127864 [3] Closes: #1094 Tested-by: Benno Lossin <benno.lossin@proton.me> Tested-by: Alice Ryhl <aliceryhl@google.com> Link: https://lore.kernel.org/r/20240806144558.114461-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

LLVM 19 is dropping support for 3DNow! in commit f0eb5587ceeb ("Remove support for 3DNow!, both intrinsics and builtins. (#96246)"): Remove support for 3DNow!, both intrinsics and builtins. (#96246) This set of instructions was only supported by AMD chips starting in the K6-2 (introduced 1998), and before the "Bulldozer" family (2011). They were never much used, as they were effectively superseded by the more-widely-implemented SSE (first implemented on the AMD side in Athlon XP in 2001). This is being done as a predecessor towards general removal of MMX register usage. Since there is almost no usage of the 3DNow! intrinsics, and no modern hardware even implements them, simple removal seems like the best option. Thus we should avoid passing these to the backend, since otherwise we get a diagnostic about it: '-3dnow' is not a recognized feature for this target (ignoring feature) '-3dnowa' is not a recognized feature for this target (ignoring feature) We could try to disable them only up to LLVM 19 (not the C side one, but the one used by `rustc`, which may be built with a range of LLVMs). However, to avoid more complexity, we can likely just remove them altogether. According to Nikita [2]: > I don't think it's needed because LLVM should not generate 3dnow > instructions unless specifically asked to, using intrinsics that > Rust does not provide in the first place. Thus do so, like Rust did for one of their builtin targets [3]. For those curious: Clang will warn only about trying to enable them (`-m3dnow{,a}`), but not about disabling them (`-mno-3dnow{,a}`), so there is no change needed there. Cc: Nikita Popov <github@npopov.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: x86@kernel.org Link: llvm/llvm-project@f0eb558 [1] Link: rust-lang/rust#127864 (comment) [2] Link: rust-lang/rust#127864 [3] Closes: Rust-for-Linux#1094 Tested-by: Benno Lossin <benno.lossin@proton.me> Tested-by: Alice Ryhl <aliceryhl@google.com> Link: https://lore.kernel.org/r/20240806144558.114461-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

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durin42 force-pushed the farewell-3dnow branch from 5973845 to 0542612 Compare July 17, 2024 14:25

durin42 force-pushed the farewell-3dnow branch from 0542612 to 6090d2b Compare July 17, 2024 14:47

antoyo reviewed Jul 17, 2024

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durin42 force-pushed the farewell-3dnow branch from 628335d to 72e2255 Compare July 17, 2024 15:45

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 18, 2024

tgross35 mentioned this pull request Jul 18, 2024

Rollup of 7 pull requests #127906

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bors merged commit e4bc3d5 into rust-lang:master Jul 18, 2024
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rustbot added this to the 1.81.0 milestone Jul 18, 2024

ojeda mentioned this pull request Aug 5, 2024

Clean 3dnow (LLVM 19, Rust 1.82.0) Rust-for-Linux/linux#1094

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Ollrogge mentioned this pull request Nov 1, 2024

Remove 3dnow features from stage4 target rust-osdev/bootloader#471

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cleanup: remove support for 3DNow! cpu features #127864

cleanup: remove support for 3DNow! cpu features #127864

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cleanup: remove support for 3DNow! cpu features #127864

cleanup: remove support for 3DNow! cpu features #127864

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