Rollup merge of #145932 - JamieCunliffe:target-feature-inlining, r=jackh726

Allow `inline(always)` with a target feature behind a unstable feature `target_feature_inline_always`.

Rather than adding the inline always attribute to the function definition, we add it to the callsite. We can then check that the target features match and that the call would be safe to inline. If the function isn't inlined due to a mismatch, we emit a warning informing the user that the function can't be inlined due to the target feature mismatch.

See tracking issue rust-lang/rust#145574

6 files changed, 154 insertions, 12 deletions

diff --git a/tests/ui/feature-gates/feature-gate-target-feature-inline-always.rs b/tests/ui/feature-gates/feature-gate-target-feature-inline-always.rs
new file mode 100644
index 00000000000..181f9a21000
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-target-feature-inline-always.rs
@@ -0,0 +1,9 @@
+//@ only-aarch64
+#[inline(always)]
+//~^ ERROR cannot use `#[inline(always)]` with `#[target_feature]`
+#[target_feature(enable="fp16")]
+fn test() {
+
+}
+
+fn main() { }
diff --git a/tests/ui/feature-gates/feature-gate-target-feature-inline-always.stderr b/tests/ui/feature-gates/feature-gate-target-feature-inline-always.stderr
new file mode 100644
index 00000000000..de54844bc29
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-target-feature-inline-always.stderr
@@ -0,0 +1,13 @@
+error[E0658]: cannot use `#[inline(always)]` with `#[target_feature]`
+  --> $DIR/feature-gate-target-feature-inline-always.rs:2:1
+   |
+LL | #[inline(always)]
+   | ^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #145574 <https://github.com/rust-lang/rust/issues/145574> for more information
+   = help: add `#![feature(target_feature_inline_always)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/target-feature/inline-always.aarch64.stderr b/tests/ui/target-feature/inline-always.aarch64.stderr
new file mode 100644
index 00000000000..a9ffb425c52
--- /dev/null
+++ b/tests/ui/target-feature/inline-always.aarch64.stderr
@@ -0,0 +1,60 @@
+warning: call to `#[inline(always)]`-annotated `target_feature_identity` requires the same target features to be inlined
+  --> $DIR/inline-always.rs:19:5
+   |
+LL |     target_feature_identity();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: function will not be inlined
+   = note: the following target features are on `target_feature_identity` but missing from `call_no_target_features`: neon, fp16
+note: `target_feature_identity` is defined here
+  --> $DIR/inline-always.rs:16:1
+   |
+LL | pub unsafe fn target_feature_identity() {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: `#[warn(inline_always_mismatching_target_features)]` on by default
+help: add `#[target_feature]` attribute to `call_no_target_features`
+   |
+LL + #[target_feature(enable = "neon,fp16")]
+LL | unsafe fn call_no_target_features() {
+   |
+
+warning: call to `#[inline(always)]`-annotated `multiple_target_features` requires the same target features to be inlined
+  --> $DIR/inline-always.rs:22:5
+   |
+LL |     multiple_target_features();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: function will not be inlined
+   = note: the following target features are on `multiple_target_features` but missing from `call_no_target_features`: fp16, sve, rdm
+note: `multiple_target_features` is defined here
+  --> $DIR/inline-always.rs:52:1
+   |
+LL | fn multiple_target_features() {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+help: add `#[target_feature]` attribute to `call_no_target_features`
+   |
+LL + #[target_feature(enable = "fp16,sve,rdm")]
+LL | unsafe fn call_no_target_features() {
+   |
+
+warning: call to `#[inline(always)]`-annotated `multiple_target_features` requires the same target features to be inlined
+  --> $DIR/inline-always.rs:28:5
+   |
+LL |     multiple_target_features();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: function will not be inlined
+   = note: the following target features are on `multiple_target_features` but missing from `call_to_first_set`: rdm
+note: `multiple_target_features` is defined here
+  --> $DIR/inline-always.rs:52:1
+   |
+LL | fn multiple_target_features() {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+help: add `#[target_feature]` attribute to `call_to_first_set`
+   |
+LL + #[target_feature(enable = "rdm")]
+LL | unsafe fn call_to_first_set() {
+   |
+
+warning: 3 warnings emitted
+
diff --git a/tests/ui/target-feature/inline-always.rs b/tests/ui/target-feature/inline-always.rs
new file mode 100644
index 00000000000..dbf46537caa
--- /dev/null
+++ b/tests/ui/target-feature/inline-always.rs
@@ -0,0 +1,54 @@
+//@ add-core-stubs
+//@ build-pass
+//@ compile-flags: --crate-type=lib
+//@ revisions: aarch64
+//@[aarch64] compile-flags: --target aarch64-unknown-linux-gnu
+//@[aarch64] needs-llvm-components: aarch64
+
+#![feature(no_core, target_feature_inline_always)]
+#![no_core]
+
+extern crate minicore;
+use minicore::*;
+
+#[inline(always)]
+#[target_feature(enable = "neon,fp16")]
+pub unsafe fn target_feature_identity() {}
+
+unsafe fn call_no_target_features() {
+    target_feature_identity();
+    //~^ WARNING call to `#[inline(always)]`-annotated `target_feature_identity` requires the same target features to be inlined [inline_always_mismatching_target_features]
+    global_feature_enabled();
+    multiple_target_features();
+    //~^ WARNING call to `#[inline(always)]`-annotated `multiple_target_features` requires the same target features to be inlined [inline_always_mismatching_target_features]
+}
+
+#[target_feature(enable = "fp16,sve")]
+unsafe fn call_to_first_set() {
+    multiple_target_features();
+    //~^ WARNING call to `#[inline(always)]`-annotated `multiple_target_features` requires the same target features to be inlined [inline_always_mismatching_target_features]
+}
+
+/* You can't have "fhm" without "fp16" */
+#[target_feature(enable = "fhm")]
+unsafe fn mismatching_features() {
+    target_feature_identity()
+}
+
+#[target_feature(enable = "fp16")]
+unsafe fn matching_target_features() {
+    target_feature_identity()
+}
+
+#[inline(always)]
+#[target_feature(enable = "neon")]
+unsafe fn global_feature_enabled() {
+
+}
+
+#[inline(always)]
+#[target_feature(enable = "fp16,sve")]
+#[target_feature(enable="rdm")]
+fn multiple_target_features() {
+
+ }
diff --git a/tests/ui/target-feature/invalid-attribute.rs b/tests/ui/target-feature/invalid-attribute.rs
index b34a48aba26..a958700231a 100644
--- a/tests/ui/target-feature/invalid-attribute.rs
+++ b/tests/ui/target-feature/invalid-attribute.rs
@@ -61,6 +61,8 @@ trait Baz {}
 
 #[inline(always)]
 //~^ ERROR: cannot use `#[inline(always)]`
+//~| NOTE: see issue #145574 <https://github.com/rust-lang/rust/issues/145574> for more information
+//~| NOTE: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 #[target_feature(enable = "sse2")]
 unsafe fn test() {}
 
diff --git a/tests/ui/target-feature/invalid-attribute.stderr b/tests/ui/target-feature/invalid-attribute.stderr
index 7b75367b48c..d85bccce441 100644
--- a/tests/ui/target-feature/invalid-attribute.stderr
+++ b/tests/ui/target-feature/invalid-attribute.stderr
@@ -106,7 +106,7 @@ LL | #[target_feature(enable = "sse2")]
    = help: `#[target_feature]` can only be applied to functions
 
 error: `#[target_feature]` attribute cannot be used on statics
-  --> $DIR/invalid-attribute.rs:67:1
+  --> $DIR/invalid-attribute.rs:69:1
    |
 LL | #[target_feature(enable = "sse2")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -114,7 +114,7 @@ LL | #[target_feature(enable = "sse2")]
    = help: `#[target_feature]` can only be applied to functions
 
 error: `#[target_feature]` attribute cannot be used on trait impl blocks
-  --> $DIR/invalid-attribute.rs:71:1
+  --> $DIR/invalid-attribute.rs:73:1
    |
 LL | #[target_feature(enable = "sse2")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -122,7 +122,7 @@ LL | #[target_feature(enable = "sse2")]
    = help: `#[target_feature]` can only be applied to functions
 
 error: `#[target_feature]` attribute cannot be used on inherent impl blocks
-  --> $DIR/invalid-attribute.rs:77:1
+  --> $DIR/invalid-attribute.rs:79:1
    |
 LL | #[target_feature(enable = "sse2")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -130,7 +130,7 @@ LL | #[target_feature(enable = "sse2")]
    = help: `#[target_feature]` can only be applied to functions
 
 error: `#[target_feature]` attribute cannot be used on expressions
-  --> $DIR/invalid-attribute.rs:98:5
+  --> $DIR/invalid-attribute.rs:100:5
    |
 LL |     #[target_feature(enable = "sse2")]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -138,18 +138,22 @@ LL |     #[target_feature(enable = "sse2")]
    = help: `#[target_feature]` can only be applied to functions
 
 error: `#[target_feature]` attribute cannot be used on closures
-  --> $DIR/invalid-attribute.rs:104:5
+  --> $DIR/invalid-attribute.rs:106:5
    |
 LL |     #[target_feature(enable = "sse2")]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: `#[target_feature]` can be applied to methods and functions
 
-error: cannot use `#[inline(always)]` with `#[target_feature]`
+error[E0658]: cannot use `#[inline(always)]` with `#[target_feature]`
   --> $DIR/invalid-attribute.rs:62:1
    |
 LL | #[inline(always)]
    | ^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #145574 <https://github.com/rust-lang/rust/issues/145574> for more information
+   = help: add `#![feature(target_feature_inline_always)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error: the feature named `foo` is not valid for this target
   --> $DIR/invalid-attribute.rs:20:18
@@ -158,7 +162,7 @@ LL | #[target_feature(enable = "foo")]
    |                  ^^^^^^^^^^^^^^ `foo` is not valid for this target
 
 error[E0046]: not all trait items implemented, missing: `foo`
-  --> $DIR/invalid-attribute.rs:73:1
+  --> $DIR/invalid-attribute.rs:75:1
    |
 LL | impl Quux for u8 {}
    | ^^^^^^^^^^^^^^^^ missing `foo` in implementation
@@ -167,7 +171,7 @@ LL |     fn foo();
    |     --------- `foo` from trait
 
 error: `#[target_feature(..)]` cannot be applied to safe trait method
-  --> $DIR/invalid-attribute.rs:87:5
+  --> $DIR/invalid-attribute.rs:89:5
    |
 LL |     #[target_feature(enable = "sse2")]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot be applied to safe trait method
@@ -176,13 +180,13 @@ LL |     fn foo() {}
    |     -------- not an `unsafe` function
 
 error[E0053]: method `foo` has an incompatible type for trait
-  --> $DIR/invalid-attribute.rs:90:5
+  --> $DIR/invalid-attribute.rs:92:5
    |
 LL |     fn foo() {}
    |     ^^^^^^^^ expected safe fn, found unsafe fn
    |
 note: type in trait
-  --> $DIR/invalid-attribute.rs:82:5
+  --> $DIR/invalid-attribute.rs:84:5
    |
 LL |     fn foo();
    |     ^^^^^^^^^
@@ -190,7 +194,7 @@ LL |     fn foo();
               found signature `#[target_features] fn()`
 
 error: the feature named `+sse2` is not valid for this target
-  --> $DIR/invalid-attribute.rs:109:18
+  --> $DIR/invalid-attribute.rs:111:18
    |
 LL | #[target_feature(enable = "+sse2")]
    |                  ^^^^^^^^^^^^^^^^ `+sse2` is not valid for this target
@@ -199,5 +203,5 @@ LL | #[target_feature(enable = "+sse2")]
 
 error: aborting due to 24 previous errors
 
-Some errors have detailed explanations: E0046, E0053, E0539.
+Some errors have detailed explanations: E0046, E0053, E0539, E0658.
 For more information about an error, try `rustc --explain E0046`.