Several LLVM versions have a bug in SelectionDAG that causes
miscompilations around conditional poisions. This was exposed due to
Rust 1.97.0 exercising the involved code path heavily and generating
segfaulting code, but the bug existed beforehand as well. The patch was
made to LLVM 23, but the tests have many conflicts, so this is a manual
backport. This backport was made by:
- applying the code change to `llvm/lib`
- hand-updating `test/CodeGen/Mips/cmov.ll` with the same diff as the PR
- updating the rest with `utils/update_llc_test_checks.py` from the LLVM
source tree, and verifying the diff against the one in the PR.
The last step made this a rather large and gnarly patch, but it's mostly
mechanical.
Rust issue: https://github.com/rust-lang/rust/issues/159035
LLVM issue: https://github.com/llvm/llvm-project/issues/208611
LLVM PR: https://github.com/llvm/llvm-project/pull/208683
Scope:
- Combination of
- Textual matches of "baseNameOf (toString"
- Redundant toString calls I've found with my latest
"lazy paths" nix branch as they force lazy fetches into
the store. More info and new PR soon.
- Only cases I believe are worthwhile or easily determined
I've determined the validity by
- testing llvmPackages instantiation
- figuring out which types can pass into any particular
toString call - "human fuzzy type checker"
Behavior considerations by type:
- `path`: converted back to a string *without* context
`baseNameOf` does not copy things to the store on its own,
equivalent to its behavior for string inputs
- `null`: converted to `""` -> may be valid input!
ok if "" would not have been acceptable anyway
- `string` itself: passed through identically -> trivial
- `attrset` with `outPath`: same coercion as built into
the `baseNameOf` function -> trivial
- other atomic types: generally not sensible inputs to
`baseNameOf` -> fuzzy but true
MLIRConfig.cmake unconditionally overwrites MLIR_TABLEGEN_EXE and does
not create an imported target, breaking standalone builds that provide
their own mlir-tblgen binary (e.g. Nix sandboxed builds).
The patch adds guards to respect caller-set MLIR_TABLEGEN_EXE,
MLIR_PDLL_TABLEGEN_EXE, and MLIR_SRC_SHARDER_TABLEGEN_EXE values, and
auto-creates an imported mlir-tblgen target for downstream consumers.
This replaces the previous dummy-target workaround in flang's
CMakeLists.txt.
Upstream issue: https://github.com/llvm/llvm-project/issues/150986
Co-authored-by: Alexander Bantyev <balsoft@balsoft.ru>
Wire flang into llvmPackages as a first-class Fortran compiler. flang
is built standalone on top of the LLVM/clang package set rather than
bundled into the llvm derivation, with passthru metadata
(`langFortran`, `isFlang`, `isClang`, `hardeningUnsupportedFlags`) so
cc-wrapper and downstream tooling can detect and adapt to it.
Driver compatibility patches backported from upstream are applied
selectively per LLVM version:
* `use-xflang-in-diagnostics` is applied to LLVM 20 and newer; it
teaches the driver to suggest `-Xflang` instead of `-Xclang` in
error messages for options only available to `flang -fc1`.
* `warn-on-fbuiltin-and-fno-builtin` and
`accept-and-ignore-some-gfortran-optimization-flags` are applied
to LLVM 20 and 21 only. LLVM 22 has equivalent behaviour merged
upstream (`warn_drv_invalid_argument_for_flang` and
`clang_ignored_gcc_optimization_f_Group` handling in
clang/lib/Driver/ToolChains/Flang.cpp), so the patches are skipped
there.
Patches live under pkgs/development/compilers/llvm/21/flang/ and are
shared across versions via patches.nix. They are applied to a private
libclang variant rather than the flang source tree because standalone
flang resolves driver/option definitions through the installed libclang
package.
Two focused passthru tests are added:
* `compile-smoke` exercises basic compilation and `@response-file`
handling.
* `driver-flags` covers wrapper flag isolation
(`NIX_CFLAGS_COMPILE` must not leak into flang;
`NIX_FFLAGS_COMPILE` must reach it), the backported driver
diagnostics, and regression coverage for previously hard-erroring
flags.
Build on the earlier standalone flang work by @picostove.
Co-authored-by: stove <stove@rivosinc.com>
Co-authored-by: acture <acture@gmail.com>
Co-authored-by: Alyssa Ross <hi@alyssa.is>
whispers