Enable run-time detection by default on powerpc64 and aarch64 linux-u…

…clibc

.github/.cspell/project-dictionary.txt

@@ -37,6 +37,7 @@ csrrci
 csrsi
 cxchg
 cxchgweak
+dlfcn
 dlsym
 DWCAS
 ecall
@@ -128,6 +129,7 @@ revidr
 rsbegin
 rsend
 rsil
+RTLD
 sbcs
 selgr
 seqlock

.github/workflows/ci.yml

@@ -324,22 +324,29 @@ jobs:
       - run: tools/test.sh -vv ${TARGET:-} ${DOCTEST_XCOMPILE:-} ${BUILD_STD:-} ${RELEASE:-}
       # We test doctest only once with the default build conditions because doctest is slow. Both api-test
       # and src/tests have extended copies of doctest, so this will not reduce test coverage.
+      # portable_atomic_no_outline_atomics only affects x86_64, AArch64, Arm, powerpc64, and RISC-V Linux.
+      # outline-atomics is disabled by default on AArch64/powerpc64 musl with static linking
+      # powerpc64le- (little-endian) is skipped because it is pwr8 by default
+      # RISC-V Linux is skipped because outline-atomics is currently disabled by default on riscv.
       - run: tools/test.sh -vv --tests ${TARGET:-} ${BUILD_STD:-} ${RELEASE:-}
         env:
           RUSTDOCFLAGS: ${{ env.RUSTDOCFLAGS }} --cfg portable_atomic_no_outline_atomics
           RUSTFLAGS: ${{ env.RUSTFLAGS }} --cfg portable_atomic_no_outline_atomics
-        # outline-atomics is disabled by default on AArch64 musl with static linking
-        if: (matrix.target == '' && !contains(matrix.rust, 'i686') || startsWith(matrix.target, 'x86_64')) || startsWith(matrix.target, 'aarch64') && !(contains(matrix.target, '-musl') && matrix.flags == '') || startsWith(matrix.target, 'armv5te') || matrix.target == 'arm-linux-androideabi'
+        if: (matrix.target == '' && !contains(matrix.rust, 'i686') || startsWith(matrix.target, 'x86_64')) || (startsWith(matrix.target, 'aarch64')  || startsWith(matrix.target, 'powerpc64-')) && !(contains(matrix.target, '-musl') && matrix.flags == '') || startsWith(matrix.target, 'armv5te') || matrix.target == 'arm-linux-androideabi'
       - run: tools/test.sh -vv --tests ${TARGET:-} ${BUILD_STD:-} ${RELEASE:-}
         env:
           # Note: detect_false cfg is intended to make it easy for portable-atomic developers to
           # test cases such as has_cmpxchg16b == false, has_lse == false,
           # __kuser_helper_version < 5, etc., and is not a public API.
           RUSTDOCFLAGS: ${{ env.RUSTDOCFLAGS }} --cfg portable_atomic_test_outline_atomics_detect_false
           RUSTFLAGS: ${{ env.RUSTFLAGS }} --cfg portable_atomic_test_outline_atomics_detect_false
-        # outline-atomics is disabled by default on AArch64 musl with static linking
+        # powerpc64 is skipped because tested below.
         if: (matrix.target == '' && !contains(matrix.rust, 'i686') || startsWith(matrix.target, 'x86_64')) || startsWith(matrix.target, 'aarch64') && !(contains(matrix.target, '-musl') && matrix.flags == '') || startsWith(matrix.target, 'armv5te') || matrix.target == 'arm-linux-androideabi'
-      # outline-atomics is disabled by default on AArch64 musl with static linking, powerpc64, and RISC-V
+      - run: tools/test.sh -vv --tests ${TARGET:-} ${BUILD_STD:-} ${RELEASE:-}
+        env:
+          QEMU_CPU: power7 # no quadword-atomics
+        if: startsWith(matrix.target, 'powerpc64-')
+      # portable_atomic_outline_atomics only affects AArch64 non-glibc-Linux/illumos, powerpc64, and RISC-V Linux.
       # powerpc64le- (little-endian) is skipped because it is pwr8 by default
       - run: tools/test.sh -vv --tests ${TARGET:-} ${BUILD_STD:-} ${RELEASE:-} --exclude api-test
         env:
@@ -353,7 +360,8 @@ jobs:
           # __kuser_helper_version < 5, etc., and is not a public API.
           RUSTDOCFLAGS: ${{ env.RUSTDOCFLAGS }} --cfg portable_atomic_outline_atomics --cfg portable_atomic_test_outline_atomics_detect_false
           RUSTFLAGS: ${{ env.RUSTFLAGS }} --cfg portable_atomic_outline_atomics --cfg portable_atomic_test_outline_atomics_detect_false
-        if: startsWith(matrix.target, 'aarch64') && contains(matrix.target, '-musl') && matrix.flags == '' || startsWith(matrix.target, 'powerpc64-') || startsWith(matrix.target, 'riscv')
+        # powerpc64 and RISC-V are skipped because tested below.
+        if: startsWith(matrix.target, 'aarch64') && contains(matrix.target, '-musl') && matrix.flags == ''
       - run: tools/test.sh -vv --tests ${TARGET:-} ${BUILD_STD:-} ${RELEASE:-} --exclude api-test
         env:
           RUSTDOCFLAGS: ${{ env.RUSTDOCFLAGS }} --cfg portable_atomic_outline_atomics
@@ -483,6 +491,7 @@ jobs:
           sync_files: runner-to-vm
           run: |
             set -CeEuxo pipefail
+            export CI=true
             export RUSTFLAGS="${RUSTFLAGS} --cfg qemu"
             # AArch64 FreeBSD/NetBSD/OpenBSD are tier 3 targets, so install Rust from package manager instead of rustup.
             case "$(uname -s)" in

README.md

@@ -170,10 +170,10 @@ RUSTFLAGS="--cfg portable_atomic_no_outline_atomics" cargo ...
   If dynamic dispatching by run-time CPU feature detection is enabled, it allows maintaining support for older CPUs while using features that are not supported on older CPUs, such as CMPXCHG16B (x86_64) and FEAT_LSE/FEAT_LSE2 (AArch64).
 
   Note:
-  - Dynamic detection is currently only enabled in Rust 1.59+ for x86_64 and AArch64, Rust 1.82+ for RISC-V (disabled by default), nightly only for powerpc64 (disabled by default) and Arm64EC, otherwise it works the same as when this cfg is set.
+  - Dynamic detection is currently only enabled in Rust 1.59+ for x86_64 and AArch64, Rust 1.82+ for RISC-V (disabled by default), nightly only for powerpc64 and Arm64EC, otherwise it works the same as when this cfg is set.
   - If the required target features are enabled at compile-time, the atomic operations are inlined.
   - This is compatible with no-std (as with all features except `std`).
-  - On some targets, run-time detection is disabled by default mainly for compatibility with older versions of operating systems or incomplete build environments, and can be enabled by `--cfg portable_atomic_outline_atomics`. (When both cfg are enabled, `*_no_*` cfg is preferred.)
+  - On some targets, run-time detection is disabled by default mainly for incomplete build environments, and can be enabled by `--cfg portable_atomic_outline_atomics`. (When both cfg are enabled, `*_no_*` cfg is preferred.)
   - Some AArch64 targets enable LLVM's `outline-atomics` target feature by default, so if you set this cfg, you may want to disable that as well. (portable-atomic's outline-atomics does not depend on the compiler-rt symbols, so even if you need to disable LLVM's outline-atomics, you may not need to disable portable-atomic's outline-atomics.)
 
   See also the [`atomic128` module's readme](https://github.com/taiki-e/portable-atomic/blob/HEAD/src/imp/atomic128/README.md).

src/cfgs.rs

@@ -299,22 +299,21 @@ mod atomic_64_macros {
                 all(
                     feature = "fallback",
                     not(portable_atomic_no_outline_atomics),
-                    portable_atomic_outline_atomics, // TODO(powerpc64): currently disabled by default
                     any(
                         all(
                             target_os = "linux",
                             any(
                                 target_env = "gnu",
                                 all(
-                                    any(target_env = "musl", target_env = "ohos"),
+                                    any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
                                     not(target_feature = "crt-static"),
                                 ),
                                 portable_atomic_outline_atomics,
                             ),
                         ),
                         target_os = "android",
                         target_os = "freebsd",
-                        all(target_os = "openbsd", portable_atomic_outline_atomics),
+                        all(target_os = "openbsd", not(target_feature = "crt-static")),
                     ),
                     not(any(miri, portable_atomic_sanitize_thread)),
                 ),
@@ -406,22 +405,21 @@ mod atomic_128_macros {
                 all(
                     feature = "fallback",
                     not(portable_atomic_no_outline_atomics),
-                    portable_atomic_outline_atomics, // TODO(powerpc64): currently disabled by default
                     any(
                         all(
                             target_os = "linux",
                             any(
                                 target_env = "gnu",
                                 all(
-                                    any(target_env = "musl", target_env = "ohos"),
+                                    any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
                                     not(target_feature = "crt-static"),
                                 ),
                                 portable_atomic_outline_atomics,
                             ),
                         ),
                         target_os = "android",
                         target_os = "freebsd",
-                        all(target_os = "openbsd", portable_atomic_outline_atomics),
+                        all(target_os = "openbsd", not(target_feature = "crt-static")),
                     ),
                     not(any(miri, portable_atomic_sanitize_thread)),
                 ),

src/imp/atomic128/README.md

@@ -11,7 +11,7 @@ Here is the table of targets that support 128-bit atomics and the instructions u
 | x86_64 | cmpxchg16b or vmovdqa | cmpxchg16b or vmovdqa | cmpxchg16b | cmpxchg16b | cmpxchg16b target feature required. vmovdqa requires Intel, AMD, or Zhaoxin CPU with AVX. <br> Both compile-time and run-time detection are supported for cmpxchg16b. vmovdqa is currently run-time detection only. <br> Requires rustc 1.59+ |
 | aarch64/arm64ec | ldxp/stxp or casp or ldp/ldiapp | ldxp/stxp or casp or stp/stilp/swpp | ldxp/stxp or casp | ldxp/stxp or casp/swpp/ldclrp/ldsetp | casp requires lse target feature, ldp/stp requires lse2 target feature, ldiapp/stilp requires lse2 and rcpc3 target features, swpp/ldclrp/ldsetp requires lse128 target feature. <br> Both compile-time and run-time detection are supported. <br> Requires rustc 1.59+ (aarch64) / nightly (arm64ec) |
 | riscv64 | amocas.q | amocas.q | amocas.q | amocas.q | Experimental because LLVM marking the corresponding target feature as experimental. Requires experimental-zacas target feature. Both compile-time and run-time detection are supported (run-time detection is currently disabled by default). <br> Requires rustc 1.82+ (LLVM 19+) |
-| powerpc64 | lq | stq | lqarx/stqcx. | lqarx/stqcx. | Requires target-cpu pwr8+ (powerpc64le is pwr8 by default). Both compile-time and run-time detection are supported (run-time detection is currently disabled by default). <br> Requires nightly |
+| powerpc64 | lq | stq | lqarx/stqcx. | lqarx/stqcx. | Requires target-cpu pwr8+ (powerpc64le is pwr8 by default). Both compile-time and run-time detection are supported. <br> Requires nightly |
 | s390x | lpq | stpq | cdsg | cdsg | Requires nightly |
 
 On compiler versions or platforms where these are not supported, the fallback implementation is used.

src/imp/atomic128/aarch64.rs

@@ -94,7 +94,10 @@ include!("macros.rs");
         target_os = "linux",
         any(
             target_env = "gnu",
-            all(any(target_env = "musl", target_env = "ohos"), not(target_feature = "crt-static")),
+            all(
+                any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
+                not(target_feature = "crt-static"),
+            ),
             portable_atomic_outline_atomics,
         ),
     ),
@@ -177,7 +180,7 @@ macro_rules! debug_assert_lse {
                     any(
                         target_env = "gnu",
                         all(
-                            any(target_env = "musl", target_env = "ohos"),
+                            any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
                             not(target_feature = "crt-static"),
                         ),
                         portable_atomic_outline_atomics,
@@ -214,7 +217,7 @@ macro_rules! debug_assert_lse2 {
                     any(
                         target_env = "gnu",
                         all(
-                            any(target_env = "musl", target_env = "ohos"),
+                            any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
                             not(target_feature = "crt-static"),
                         ),
                         portable_atomic_outline_atomics,
@@ -255,7 +258,7 @@ macro_rules! debug_assert_lse128 {
                     any(
                         target_env = "gnu",
                         all(
-                            any(target_env = "musl", target_env = "ohos"),
+                            any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
                             not(target_feature = "crt-static"),
                         ),
                         portable_atomic_outline_atomics,
@@ -296,7 +299,7 @@ macro_rules! debug_assert_rcpc3 {
                     any(
                         target_env = "gnu",
                         all(
-                            any(target_env = "musl", target_env = "ohos"),
+                            any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
                             not(target_feature = "crt-static"),
                         ),
                         portable_atomic_outline_atomics,
@@ -509,7 +512,7 @@ unsafe fn atomic_load(src: *mut u128, order: Ordering) -> u128 {
                 any(
                     target_env = "gnu",
                     all(
-                        any(target_env = "musl", target_env = "ohos"),
+                        any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
                         not(target_feature = "crt-static"),
                     ),
                     portable_atomic_outline_atomics,
@@ -606,7 +609,7 @@ unsafe fn atomic_load(src: *mut u128, order: Ordering) -> u128 {
                 any(
                     target_env = "gnu",
                     all(
-                        any(target_env = "musl", target_env = "ohos"),
+                        any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
                         not(target_feature = "crt-static"),
                     ),
                     portable_atomic_outline_atomics,
@@ -932,7 +935,7 @@ unsafe fn atomic_store(dst: *mut u128, val: u128, order: Ordering) {
                 any(
                     target_env = "gnu",
                     all(
-                        any(target_env = "musl", target_env = "ohos"),
+                        any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
                         not(target_feature = "crt-static"),
                     ),
                     portable_atomic_outline_atomics,
@@ -1037,7 +1040,7 @@ unsafe fn atomic_store(dst: *mut u128, val: u128, order: Ordering) {
                 any(
                     target_env = "gnu",
                     all(
-                        any(target_env = "musl", target_env = "ohos"),
+                        any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
                         not(target_feature = "crt-static"),
                     ),
                     portable_atomic_outline_atomics,
@@ -1263,7 +1266,7 @@ unsafe fn atomic_compare_exchange(
                 any(
                     target_env = "gnu",
                     all(
-                        any(target_env = "musl", target_env = "ohos"),
+                        any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
                         not(target_feature = "crt-static"),
                     ),
                     portable_atomic_outline_atomics,
@@ -1402,7 +1405,7 @@ unsafe fn atomic_compare_exchange(
                 any(
                     target_env = "gnu",
                     all(
-                        any(target_env = "musl", target_env = "ohos"),
+                        any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
                         not(target_feature = "crt-static"),
                     ),
                     portable_atomic_outline_atomics,

src/imp/atomic128/mod.rs

@@ -28,22 +28,21 @@ pub(super) mod aarch64;
         all(
             feature = "fallback",
             not(portable_atomic_no_outline_atomics),
-            any(test, portable_atomic_outline_atomics), // TODO(powerpc64): currently disabled by default
             any(
                 all(
                     target_os = "linux",
                     any(
                         target_env = "gnu",
                         all(
-                            any(target_env = "musl", target_env = "ohos"),
+                            any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
                             not(target_feature = "crt-static"),
                         ),
                         portable_atomic_outline_atomics,
                     ),
                 ),
                 target_os = "android",
                 target_os = "freebsd",
-                all(target_os = "openbsd", portable_atomic_outline_atomics),
+                all(target_os = "openbsd", not(target_feature = "crt-static")),
             ),
             not(any(miri, portable_atomic_sanitize_thread)),
         ),

src/imp/atomic128/powerpc64.rs

@@ -41,7 +41,6 @@ mod fallback;
 // On musl with static linking, it seems that getauxval is not always available.
 // See detect/auxv.rs for more.
 #[cfg(not(portable_atomic_no_outline_atomics))]
-#[cfg(any(test, portable_atomic_outline_atomics))] // TODO(powerpc64): currently disabled by default
 #[cfg(any(
     test,
     not(any(
@@ -54,13 +53,16 @@ mod fallback;
         target_os = "linux",
         any(
             target_env = "gnu",
-            all(any(target_env = "musl", target_env = "ohos"), not(target_feature = "crt-static")),
+            all(
+                any(target_env = "musl", target_env = "ohos", target_env = "uclibc"),
+                not(target_feature = "crt-static"),
+            ),
             portable_atomic_outline_atomics,
         ),
     ),
     target_os = "android",
     target_os = "freebsd",
-    all(target_os = "openbsd", portable_atomic_outline_atomics),
+    all(target_os = "openbsd", not(target_feature = "crt-static")),
 ))]
 #[path = "../detect/auxv.rs"]
 mod detect;