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[meta-lts-mixins,scarthgap/rust,8/8] rust: backport cstring-merging test fix for PowerPC targets

Message ID 96deb45139df027473faf0938fe006d33c45c375.1755451833.git.scott.murray@konsulko.com
State New
Headers show
Series Update to Rust 1.88.0 | expand

Commit Message

Scott Murray Aug. 17, 2025, 5:31 p.m. UTC 
From: Peter Tatrai <peter.tatrai.ext@siemens.com>

The Rust cstring-merging assembly test was failing on PowerPC targets due to
LLVM's GlobalMerge optimization pass merging all global string constants into
a single merged global. This caused the test's CHECK directives to fail as
they expected separate .Lanon labels for each string literal ("foo", "bar",
"baz").

The test verifies that C-style string literals are correctly placed in
mergeable read-only sections (.rodata.str1.1) with proper section flags
(aMS - Allocatable, Merge, Strings) for linker optimization.

This backports the upstream fix that disables the GlobalMerge pass
(-Cllvm-args=-enable-global-merge=0) specifically for this test, allowing
it to verify the expected assembly structure without interference from
the optimization.

Fixes test failure:
- tests/assembly/cstring-merging.rs on powerpc-poky-linux-gnu

Backport of https://github.com/rust-lang/rust/commit/2d51acd2fbcbadb6f30709c5dd305494d413d388

Signed-off-by: Peter Tatrai <peter.tatrai.ext@siemens.com>
Tested-by: Peter Marko <peter.marko@siemens.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(adapted from oe-core commit 2435b16b050ebdca0f70fe9ed1eebfdd3bacf19d)
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
---
 .../backport-fix-test-string-merging.patch    | 27 +++++++++++++++++++
 recipes-devtools/rust/rust-source.inc         |  1 +
 2 files changed, 28 insertions(+)
 create mode 100644 recipes-devtools/rust/files/backport-fix-test-string-merging.patch
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Patch

diff --git a/recipes-devtools/rust/files/backport-fix-test-string-merging.patch b/recipes-devtools/rust/files/backport-fix-test-string-merging.patch
new file mode 100644
index 0000000..1e72c10
--- /dev/null
+++ b/recipes-devtools/rust/files/backport-fix-test-string-merging.patch
@@ -0,0 +1,27 @@ 
+From 2d51acd2fbcbadb6f30709c5dd305494d413d388 Mon Sep 17 00:00:00 2001
+From: Jens Reidel <adrian@travitia.xyz>
+Date: Fri, 18 Jul 2025 19:44:20 +0200
+Subject: [PATCH] tests: assembly: cstring-merging: Disable GlobalMerge pass
+
+The test relies on LLVM not merging all the globals into one and would
+currently otherwise fail on powerpc64le.
+
+Signed-off-by: Peter Tatrai <Peter.Tatrai@siemens.com>
+Upstream-Status: Backport [https://github.com/rust-lang/rust/commit/2d51acd2fbcbadb6f30709c5dd305494d413d388]
+---
+ tests/assembly/cstring-merging.rs | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/tests/assembly/cstring-merging.rs b/tests/assembly/cstring-merging.rs
+index f7d0775f7affd..03688e0068b79 100644
+--- a/tests/assembly/cstring-merging.rs
++++ b/tests/assembly/cstring-merging.rs
+@@ -2,7 +2,7 @@
+ // other architectures (including ARM and x86-64) use the prefix `.Lanon.`
+ //@ only-linux
+ //@ assembly-output: emit-asm
+-//@ compile-flags: --crate-type=lib -Copt-level=3
++//@ compile-flags: --crate-type=lib -Copt-level=3 -Cllvm-args=-enable-global-merge=0
+ //@ edition: 2024
+ 
+ use std::ffi::CStr;
diff --git a/recipes-devtools/rust/rust-source.inc b/recipes-devtools/rust/rust-source.inc
index 6174a3a..73aa14b 100644
--- a/recipes-devtools/rust/rust-source.inc
+++ b/recipes-devtools/rust/rust-source.inc
@@ -11,6 +11,7 @@  SRC_URI += "https://static.rust-lang.org/dist/rustc-${RUST_VERSION}-src.tar.xz;n
             file://0001-Disable-libunwind-cross-architecture-unwinding.patch;patchdir=${RUSTSRC} \
             file://triagebot.patch;patchdir=${RUSTSRC} \
             file://0001-riscv32-Define-plain-syscalls-as-their-time64-varian.patch;patchdir=${RUSTSRC} \
+            file://backport-fix-test-string-merging.patch;patchdir=${RUSTSRC} \
 "
 SRC_URI[rust.sha256sum] = "0c1dcbb4f762513d021e1a282c0ac58c0a423642b3a6bf581cafb5414df4193e"