Remove the explicit branch hint from const_panic

library/core/src/intrinsics/mod.rs

@@ -2402,8 +2402,7 @@ pub const fn const_eval_select<ARG: Tuple, F, G, RET>(
 /// The `@capture` block declares which surrounding variables / expressions can be
 /// used inside the `if const`.
 /// Note that the two arms of this `if` really each become their own function, which is why the
-/// macro supports setting attributes for those functions. The runtime function is always
-/// marked as `#[inline]`.
+/// macro supports setting attributes for those functions. Both functions are marked as `#[inline]`.
 ///
 /// See [`const_eval_select()`] for the rules and requirements around that intrinsic.
 pub(crate) macro const_eval_select {
@@ -2413,35 +2412,14 @@ pub const fn const_eval_select<ARG: Tuple, F, G, RET>(
             $(#[$compiletime_attr:meta])* $compiletime:block
         else
             $(#[$runtime_attr:meta])* $runtime:block
-    ) => {
-        // Use the `noinline` arm, after adding explicit `inline` attributes
-        $crate::intrinsics::const_eval_select!(
-            @capture$([$($binders)*])? { $($arg : $ty = $val),* } $(-> $ret)? :
-            #[noinline]
-            if const
-                #[inline] // prevent codegen on this function
-                $(#[$compiletime_attr])*
-                $compiletime
-            else
-                #[inline] // avoid the overhead of an extra fn call
-                $(#[$runtime_attr])*
-                $runtime
-        )
-    },
-    // With a leading #[noinline], we don't add inline attributes
-    (
-        @capture$([$($binders:tt)*])? { $($arg:ident : $ty:ty = $val:expr),* $(,)? } $( -> $ret:ty )? :
-        #[noinline]
-        if const
-            $(#[$compiletime_attr:meta])* $compiletime:block
-        else
-            $(#[$runtime_attr:meta])* $runtime:block
     ) => {{
+        #[inline]
         $(#[$runtime_attr])*
         fn runtime$(<$($binders)*>)?($($arg: $ty),*) $( -> $ret )? {
             $runtime
         }
 
+        #[inline]
         $(#[$compiletime_attr])*
         const fn compiletime$(<$($binders)*>)?($($arg: $ty),*) $( -> $ret )? {
             // Don't warn if one of the arguments is unused.

library/core/src/panic.rs

@@ -166,10 +166,9 @@ fn as_str(&mut self) -> Option<&str> {
         const fn do_panic($($arg: $ty),*) -> ! {
             $crate::intrinsics::const_eval_select!(
                 @capture { $($arg: $ty = $arg),* } -> !:
-                #[noinline]
-                if const #[track_caller] #[inline] { // Inline this, to prevent codegen
+                if const #[track_caller] {
                     $crate::panic!($const_msg)
-                } else #[track_caller] { // Do not inline this, it makes perf worse
+                } else #[track_caller] {
                     $crate::panic!($runtime_msg)
                 }
             )
@@ -195,7 +194,7 @@ const fn do_panic($($arg: $ty),*) -> ! {
 #[doc(hidden)]
 pub macro const_assert {
     ($condition: expr, $const_msg:literal, $runtime_msg:literal, $($arg:tt)*) => {{
-        if !$crate::intrinsics::likely($condition) {
+        if !($condition) {
             $crate::panic::const_panic!($const_msg, $runtime_msg, $($arg)*)
         }
     }}

tests/codegen-llvm/intrinsics/likely_assert.rs

@@ -1,17 +1,31 @@
 //@ compile-flags: -Copt-level=3
+#![feature(panic_internals, const_eval_select, rustc_allow_const_fn_unstable, core_intrinsics)]
 #![crate_type = "lib"]
 
+// check that assert! and const_assert! emit branch weights
+
 #[no_mangle]
 pub fn test_assert(x: bool) {
     assert!(x);
 }
 
-// check that assert! emits branch weights
-
 // CHECK-LABEL: @test_assert(
 // CHECK: br i1 %x, label %bb2, label %bb1, !prof ![[NUM:[0-9]+]]
 // CHECK: bb1:
 // CHECK: panic
 // CHECK: bb2:
 // CHECK: ret void
+
+#[no_mangle]
+pub fn test_const_assert(x: bool) {
+    core::panic::const_assert!(x, "", "",);
+}
+
+// CHECK-LABEL: @test_const_assert(
+// CHECK: br i1 %x, label %bb2, label %bb1, !prof ![[NUM:[0-9]+]]
+// CHECK: bb1:
+// CHECK: panic
+// CHECK: bb2:
+// CHECK: ret void
+
 // CHECK: ![[NUM]] = !{!"branch_weights", {{(!"expected", )?}}i32 2000, i32 1}