Auto merge of #87590 - Amanieu:deprecate_llvm_asm, r=nagisa

Deprecate llvm_asm! We would like to remove `llvm_asm!` from the compiler once `asm!` is stabilized. This PR deprecates `llvm_asm!` to encourage any remaining users to migrate to `asm!` (or if `asm!` is not supported for their target, to add this support to rustc). The only remaining user of `llvm_asm!` in the standard library was `black_box`, which has been rewritten to use volatile operations when `asm!` is not available on the current target. cc `@rust-lang/wg-inline-asm` cc `@RalfJung` for the changes to `black_box` which might affect Miri. r? `@nagisa`
rust-lang · Aug 15, 2021 · 2bd17c1 · 2bd17c1
2 parents 2d2bc94 + 632a400
commit 2bd17c1
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diff --git a/library/core/src/hint.rs b/library/core/src/hint.rs
@@ -155,6 +155,7 @@ pub fn spin_loop() {
 #[inline]
 #[unstable(feature = "bench_black_box", issue = "64102")]
 #[cfg_attr(not(bootstrap), allow(unused_mut))]
+#[cfg_attr(bootstrap, allow(deprecated))]
 pub fn black_box<T>(mut dummy: T) -> T {
     #[cfg(bootstrap)]
     // SAFETY: the inline assembly is a no-op.

diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs
@@ -1347,6 +1347,10 @@ pub(crate) mod builtin {
         issue = "70173",
         reason = "prefer using the new asm! syntax instead"
     )]
+    #[rustc_deprecated(
+        since = "1.56",
+        reason = "will be removed from the compiler, use asm! instead"
+    )]
     #[rustc_builtin_macro]
     #[macro_export]
     macro_rules! llvm_asm {

diff --git a/src/test/ui/abi/abi-sysv64-register-usage.rs b/src/test/ui/abi/abi-sysv64-register-usage.rs
@@ -7,6 +7,7 @@
 // ignore-aarch64
 
 #![feature(llvm_asm)]
+#![allow(deprecated)] // llvm_asm!
 
 #[cfg(target_arch = "x86_64")]
 pub extern "sysv64" fn all_the_registers(rdi: i64, rsi: i64, rdx: i64,

diff --git a/src/test/ui/asm/naked-functions.rs b/src/test/ui/asm/naked-functions.rs
@@ -4,6 +4,7 @@
 #![feature(naked_functions)]
 #![feature(or_patterns)]
 #![crate_type = "lib"]
+#![allow(deprecated)] // llvm_asm!
 
 #[repr(C)]
 pub struct P { x: u8, y: u16 }

diff --git a/src/test/ui/asm/naked-functions.stderr b/src/test/ui/asm/naked-functions.stderr
@@ -1,43 +1,43 @@
 error: asm with the `pure` option must have at least one output
-  --> $DIR/naked-functions.rs:126:14
+  --> $DIR/naked-functions.rs:127:14
    |
 LL |     asm!("", options(readonly, nostack), options(pure));
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^  ^^^^^^^^^^^^^
 
 error: patterns not allowed in naked function parameters
-  --> $DIR/naked-functions.rs:13:5
+  --> $DIR/naked-functions.rs:14:5
    |
 LL |     mut a: u32,
    |     ^^^^^
 
 error: patterns not allowed in naked function parameters
-  --> $DIR/naked-functions.rs:15:5
+  --> $DIR/naked-functions.rs:16:5
    |
 LL |     &b: &i32,
    |     ^^
 
 error: patterns not allowed in naked function parameters
-  --> $DIR/naked-functions.rs:17:6
+  --> $DIR/naked-functions.rs:18:6
    |
 LL |     (None | Some(_)): Option<std::ptr::NonNull<u8>>,
    |      ^^^^^^^^^^^^^^
 
 error: patterns not allowed in naked function parameters
-  --> $DIR/naked-functions.rs:19:5
+  --> $DIR/naked-functions.rs:20:5
    |
 LL |     P { x, y }: P,
    |     ^^^^^^^^^^
 
 error: referencing function parameters is not allowed in naked functions
-  --> $DIR/naked-functions.rs:29:5
+  --> $DIR/naked-functions.rs:30:5
    |
 LL |     a + 1
    |     ^
    |
    = help: follow the calling convention in asm block to use parameters
 
 warning: naked functions must contain a single asm block
-  --> $DIR/naked-functions.rs:26:1
+  --> $DIR/naked-functions.rs:27:1
    |
 LL | / pub unsafe extern "C" fn inc(a: u32) -> u32 {
 LL | |
@@ -53,15 +53,15 @@ LL | | }
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 error: referencing function parameters is not allowed in naked functions
-  --> $DIR/naked-functions.rs:35:31
+  --> $DIR/naked-functions.rs:36:31
    |
 LL |     asm!("/* {0} */", in(reg) a, options(noreturn));
    |                               ^
    |
    = help: follow the calling convention in asm block to use parameters
 
 warning: only `const` and `sym` operands are supported in naked functions
-  --> $DIR/naked-functions.rs:35:23
+  --> $DIR/naked-functions.rs:36:23
    |
 LL |     asm!("/* {0} */", in(reg) a, options(noreturn));
    |                       ^^^^^^^^^
@@ -70,7 +70,7 @@ LL |     asm!("/* {0} */", in(reg) a, options(noreturn));
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: naked functions must contain a single asm block
-  --> $DIR/naked-functions.rs:42:1
+  --> $DIR/naked-functions.rs:43:1
    |
 LL | / pub unsafe extern "C" fn inc_closure(a: u32) -> u32 {
 LL | |
@@ -84,7 +84,7 @@ LL | | }
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: only `const` and `sym` operands are supported in naked functions
-  --> $DIR/naked-functions.rs:62:10
+  --> $DIR/naked-functions.rs:63:10
    |
 LL |          in(reg) a,
    |          ^^^^^^^^^
@@ -102,7 +102,7 @@ LL |          out(reg) e,
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: asm in naked functions must use `noreturn` option
-  --> $DIR/naked-functions.rs:59:5
+  --> $DIR/naked-functions.rs:60:5
    |
 LL | /     asm!("/* {0} {1} {2} {3} {4} {5} {6} */",
 LL | |
@@ -117,7 +117,7 @@ LL | |     );
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: naked functions must contain a single asm block
-  --> $DIR/naked-functions.rs:49:1
+  --> $DIR/naked-functions.rs:50:1
    |
 LL | / pub unsafe extern "C" fn unsupported_operands() {
 LL | |
@@ -141,7 +141,7 @@ LL | | }
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: naked functions must contain a single asm block
-  --> $DIR/naked-functions.rs:75:1
+  --> $DIR/naked-functions.rs:76:1
    |
 LL | / pub extern "C" fn missing_assembly() {
 LL | |
@@ -153,7 +153,7 @@ LL | | }
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: asm in naked functions must use `noreturn` option
-  --> $DIR/naked-functions.rs:84:5
+  --> $DIR/naked-functions.rs:85:5
    |
 LL |     asm!("");
    |     ^^^^^^^^^
@@ -162,7 +162,7 @@ LL |     asm!("");
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: asm in naked functions must use `noreturn` option
-  --> $DIR/naked-functions.rs:87:5
+  --> $DIR/naked-functions.rs:88:5
    |
 LL |     asm!("");
    |     ^^^^^^^^^
@@ -171,7 +171,7 @@ LL |     asm!("");
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: asm in naked functions must use `noreturn` option
-  --> $DIR/naked-functions.rs:90:5
+  --> $DIR/naked-functions.rs:91:5
    |
 LL |     asm!("");
    |     ^^^^^^^^^
@@ -180,7 +180,7 @@ LL |     asm!("");
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: naked functions must contain a single asm block
-  --> $DIR/naked-functions.rs:81:1
+  --> $DIR/naked-functions.rs:82:1
    |
 LL | / pub extern "C" fn too_many_asm_blocks() {
 LL | |
@@ -202,15 +202,15 @@ LL | | }
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 error: referencing function parameters is not allowed in naked functions
-  --> $DIR/naked-functions.rs:101:11
+  --> $DIR/naked-functions.rs:102:11
    |
 LL |         *&y
    |           ^
    |
    = help: follow the calling convention in asm block to use parameters
 
 warning: naked functions must contain a single asm block
-  --> $DIR/naked-functions.rs:98:5
+  --> $DIR/naked-functions.rs:99:5
    |
 LL | /     pub extern "C" fn inner(y: usize) -> usize {
 LL | |
@@ -225,7 +225,7 @@ LL | |     }
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: the LLVM-style inline assembly is unsupported in naked functions
-  --> $DIR/naked-functions.rs:111:5
+  --> $DIR/naked-functions.rs:112:5
    |
 LL |     llvm_asm!("");
    |     ^^^^^^^^^^^^^^
@@ -236,7 +236,7 @@ LL |     llvm_asm!("");
    = note: this warning originates in the macro `llvm_asm` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 warning: naked functions must contain a single asm block
-  --> $DIR/naked-functions.rs:108:1
+  --> $DIR/naked-functions.rs:109:1
    |
 LL | / unsafe extern "C" fn llvm() -> ! {
 LL | |
@@ -252,7 +252,7 @@ LL | | }
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: asm options unsupported in naked functions: `nomem`, `preserves_flags`
-  --> $DIR/naked-functions.rs:119:5
+  --> $DIR/naked-functions.rs:120:5
    |
 LL |     asm!("", options(nomem, preserves_flags, noreturn));
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -261,7 +261,7 @@ LL |     asm!("", options(nomem, preserves_flags, noreturn));
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: asm options unsupported in naked functions: `nostack`, `pure`, `readonly`
-  --> $DIR/naked-functions.rs:126:5
+  --> $DIR/naked-functions.rs:127:5
    |
 LL |     asm!("", options(readonly, nostack), options(pure));
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -270,7 +270,7 @@ LL |     asm!("", options(readonly, nostack), options(pure));
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: asm in naked functions must use `noreturn` option
-  --> $DIR/naked-functions.rs:126:5
+  --> $DIR/naked-functions.rs:127:5
    |
 LL |     asm!("", options(readonly, nostack), options(pure));
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -279,21 +279,21 @@ LL |     asm!("", options(readonly, nostack), options(pure));
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: Rust ABI is unsupported in naked functions
-  --> $DIR/naked-functions.rs:135:15
+  --> $DIR/naked-functions.rs:136:15
    |
 LL | pub unsafe fn default_abi() {
    |               ^^^^^^^^^^^
    |
    = note: `#[warn(undefined_naked_function_abi)]` on by default
 
 warning: Rust ABI is unsupported in naked functions
-  --> $DIR/naked-functions.rs:141:29
+  --> $DIR/naked-functions.rs:142:29
    |
 LL | pub unsafe extern "Rust" fn rust_abi() {
    |                             ^^^^^^^^
 
 warning: naked functions cannot be inlined
-  --> $DIR/naked-functions.rs:175:1
+  --> $DIR/naked-functions.rs:176:1
    |
 LL | #[inline]
    | ^^^^^^^^^
@@ -302,7 +302,7 @@ LL | #[inline]
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: naked functions cannot be inlined
-  --> $DIR/naked-functions.rs:183:1
+  --> $DIR/naked-functions.rs:184:1
    |
 LL | #[inline(always)]
    | ^^^^^^^^^^^^^^^^^
@@ -311,7 +311,7 @@ LL | #[inline(always)]
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: naked functions cannot be inlined
-  --> $DIR/naked-functions.rs:191:1
+  --> $DIR/naked-functions.rs:192:1
    |
 LL | #[inline(never)]
    | ^^^^^^^^^^^^^^^^
@@ -320,7 +320,7 @@ LL | #[inline(never)]
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: naked functions cannot be inlined
-  --> $DIR/naked-functions.rs:199:1
+  --> $DIR/naked-functions.rs:200:1
    |
 LL | #[inline]
    | ^^^^^^^^^
@@ -329,7 +329,7 @@ LL | #[inline]
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: naked functions cannot be inlined
-  --> $DIR/naked-functions.rs:202:1
+  --> $DIR/naked-functions.rs:203:1
    |
 LL | #[inline(always)]
    | ^^^^^^^^^^^^^^^^^
@@ -338,7 +338,7 @@ LL | #[inline(always)]
    = note: for more information, see issue #32408 <https://github.com/rust-lang/rust/issues/32408>
 
 warning: naked functions cannot be inlined
-  --> $DIR/naked-functions.rs:205:1
+  --> $DIR/naked-functions.rs:206:1
    |
 LL | #[inline(never)]
    | ^^^^^^^^^^^^^^^^

diff --git a/src/test/ui/asm/rustfix-asm.fixed b/src/test/ui/asm/rustfix-asm.fixed
@@ -2,6 +2,7 @@
 // only-x86_64
 
 #![feature(asm, llvm_asm)]
+#![allow(deprecated)] // llvm_asm!
 
 fn main() {
     unsafe {

diff --git a/src/test/ui/asm/rustfix-asm.rs b/src/test/ui/asm/rustfix-asm.rs
@@ -2,6 +2,7 @@
 // only-x86_64
 
 #![feature(asm, llvm_asm)]
+#![allow(deprecated)] // llvm_asm!
 
 fn main() {
     unsafe {

diff --git a/src/test/ui/asm/rustfix-asm.stderr b/src/test/ui/asm/rustfix-asm.stderr
@@ -1,5 +1,5 @@
 error: the legacy LLVM-style asm! syntax is no longer supported
-  --> $DIR/rustfix-asm.rs:10:9
+  --> $DIR/rustfix-asm.rs:11:9
    |
 LL |         asm!("" :: "r" (x));
    |         ----^^^^^^^^^^^^^^^^
@@ -10,7 +10,7 @@ LL |         asm!("" :: "r" (x));
    = note: alternatively, switch to llvm_asm! to keep your code working as it is
 
 error: the legacy LLVM-style asm! syntax is no longer supported
-  --> $DIR/rustfix-asm.rs:12:9
+  --> $DIR/rustfix-asm.rs:13:9
    |
 LL |         asm!("" : "=r" (y));
    |         ----^^^^^^^^^^^^^^^^

diff --git a/src/test/ui/ast-json/ast-json-ice.rs b/src/test/ui/ast-json/ast-json-ice.rs
@@ -9,6 +9,7 @@
 // dont-check-compiler-stdout - don't check for any AST change.
 
 #![feature(llvm_asm)]
+#![allow(deprecated)] // llvm_asm!
 
 enum V {
     A(i32),

diff --git a/src/test/ui/borrowck/borrowck-asm.rs b/src/test/ui/borrowck/borrowck-asm.rs
@@ -8,6 +8,7 @@
 // ignore-sparc64
 
 #![feature(llvm_asm)]
+#![allow(deprecated)] // llvm_asm!
 
 #[cfg(any(target_arch = "x86",
             target_arch = "x86_64",