kbuild: rust: add CONFIG_RUSTC_LLVM_VERSION

Each version of Rust supports a range of LLVM versions. There are cases where
we want to gate a config on the LLVM version instead of the Rust version.
Normalized cfi integer tags are one example [1].

The invocation of rustc-version is being moved from init/Kconfig to
scripts/Kconfig.include for consistency with cc-version.

Link: https://lore.kernel.org/all/20240925-cfi-norm-kasan-fix-v1-1-0328985cdf33@google.com/ [1]
Signed-off-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20241011114040.3900487-1-gary@garyguo.net
[ Added missing `-llvm` to the Usage documentation. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Gary Guo 2024-10-11 12:40:33 +01:00 committed by Miguel Ojeda
parent e72a076c62
commit af0121c2d3
3 changed files with 30 additions and 1 deletions

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@ -62,7 +62,7 @@ config LLD_VERSION
config RUSTC_VERSION
int
default $(shell,$(srctree)/scripts/rustc-version.sh $(RUSTC))
default $(rustc-version)
help
It does not depend on `RUST` since that one may need to use the version
in a `depends on`.
@ -78,6 +78,10 @@ config RUST_IS_AVAILABLE
In particular, the Makefile target 'rustavailable' is useful to check
why the Rust toolchain is not being detected.
config RUSTC_LLVM_VERSION
int
default $(rustc-llvm-version)
config CC_CAN_LINK
bool
default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT

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@ -65,6 +65,9 @@ cc-option-bit = $(if-success,$(CC) -Werror $(1) -E -x c /dev/null -o /dev/null,$
m32-flag := $(cc-option-bit,-m32)
m64-flag := $(cc-option-bit,-m64)
rustc-version := $(shell,$(srctree)/scripts/rustc-version.sh $(RUSTC))
rustc-llvm-version := $(shell,$(srctree)/scripts/rustc-llvm-version.sh $(RUSTC))
# $(rustc-option,<flag>)
# Return y if the Rust compiler supports <flag>, n otherwise
# Calls to this should be guarded so that they are not evaluated if

22
scripts/rustc-llvm-version.sh Executable file
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@ -0,0 +1,22 @@
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
#
# Usage: $ ./rustc-llvm-version.sh rustc
#
# Print the LLVM version that the Rust compiler uses in a 6 digit form.
# Convert the version string x.y.z to a canonical up-to-6-digits form.
get_canonical_version()
{
IFS=.
set -- $1
echo $((10000 * $1 + 100 * $2 + $3))
}
if output=$("$@" --version --verbose 2>/dev/null | grep LLVM); then
set -- $output
get_canonical_version $3
else
echo 0
exit 1
fi