Make rust-intrinsic ABI unwindable

compiler/rustc_middle/src/ty/layout.rs

@@ -1226,10 +1226,11 @@ pub fn fn_can_unwind(tcx: TyCtxt<'_>, fn_def_id: Option<DefId>, abi: SpecAbi) ->
         | AvrNonBlockingInterrupt
         | CCmseNonSecureCall
         | Wasm
-        | RustIntrinsic
         | PlatformIntrinsic
         | Unadjusted => false,
-        Rust | RustCall | RustCold => tcx.sess.panic_strategy() == PanicStrategy::Unwind,
+        Rust | RustCall | RustCold | RustIntrinsic => {
+            tcx.sess.panic_strategy() == PanicStrategy::Unwind
+        }
     }
 }
 

library/core/src/ffi/mod.rs

@@ -615,12 +615,15 @@ impl<'f> Drop for VaListImpl<'f> {
 extern "rust-intrinsic" {
     /// Destroy the arglist `ap` after initialization with `va_start` or
     /// `va_copy`.
+    #[rustc_nounwind]
     fn va_end(ap: &mut VaListImpl<'_>);
 
     /// Copies the current location of arglist `src` to the arglist `dst`.
+    #[rustc_nounwind]
     fn va_copy<'f>(dest: *mut VaListImpl<'f>, src: &VaListImpl<'f>);
 
     /// Loads an argument of type `T` from the `va_list` `ap` and increment the
     /// argument `ap` points to.
+    #[rustc_nounwind]
     fn va_arg<T: sealed_trait::VaArgSafe>(ap: &mut VaListImpl<'_>) -> T;
 }

library/core/src/ptr/mod.rs

@@ -1371,6 +1371,7 @@ pub const unsafe fn write<T>(dst: *mut T, src: T) {
     // as `intrinsics::copy_nonoverlapping` is a wrapper function.
     extern "rust-intrinsic" {
         #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
+        #[rustc_nounwind]
         fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize);
     }
 

library/std/src/panicking.rs

@@ -498,6 +498,7 @@ pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>>
     // This function cannot be marked as `unsafe` because `intrinsics::r#try`
     // expects normal function pointers.
     #[inline]
+    #[rustc_nounwind] // `intrinsic::r#try` requires catch fn to be nounwind
     fn do_catch<F: FnOnce() -> R, R>(data: *mut u8, payload: *mut u8) {
         // SAFETY: this is the responsibility of the caller, see above.
         //

tests/mir-opt/issue_104451_unwindable_intrinsics.main.AbortUnwindingCalls.after.mir

@@ -0,0 +1,25 @@
+// MIR for `main` after AbortUnwindingCalls
+
+fn main() -> () {
+    let mut _0: ();                      // return place in scope 0 at $DIR/issue_104451_unwindable_intrinsics.rs:+0:11: +0:11
+    let mut _1: !;                       // in scope 0 at $DIR/issue_104451_unwindable_intrinsics.rs:+2:9: +2:62
+    let mut _2: ();                      // in scope 0 at $DIR/issue_104451_unwindable_intrinsics.rs:+2:45: +2:47
+    scope 1 {
+    }
+
+    bb0: {
+        StorageLive(_1);                 // scope 1 at $DIR/issue_104451_unwindable_intrinsics.rs:+2:9: +2:62
+        StorageLive(_2);                 // scope 1 at $DIR/issue_104451_unwindable_intrinsics.rs:+2:45: +2:47
+        _2 = ();                         // scope 1 at $DIR/issue_104451_unwindable_intrinsics.rs:+2:45: +2:47
+        _1 = const_eval_select::<(), fn() -> ! {ow_ct}, fn() -> ! {ow_ct}, !>(move _2, ow_ct, ow_ct); // scope 1 at $DIR/issue_104451_unwindable_intrinsics.rs:+2:9: +2:62
+                                         // mir::Constant
+                                         // + span: $DIR/issue_104451_unwindable_intrinsics.rs:8:9: 8:44
+                                         // + literal: Const { ty: unsafe extern "rust-intrinsic" fn((), fn() -> ! {ow_ct}, fn() -> ! {ow_ct}) -> ! {const_eval_select::<(), fn() -> ! {ow_ct}, fn() -> ! {ow_ct}, !>}, val: Value(<ZST>) }
+                                         // mir::Constant
+                                         // + span: $DIR/issue_104451_unwindable_intrinsics.rs:8:49: 8:54
+                                         // + literal: Const { ty: fn() -> ! {ow_ct}, val: Value(<ZST>) }
+                                         // mir::Constant
+                                         // + span: $DIR/issue_104451_unwindable_intrinsics.rs:8:56: 8:61
+                                         // + literal: Const { ty: fn() -> ! {ow_ct}, val: Value(<ZST>) }
+    }
+}

tests/mir-opt/issue_104451_unwindable_intrinsics.rs

@@ -0,0 +1,14 @@
+// Check that `UnwindAction::Unreachable` is not generated for unwindable intrinsics.
+// ignore-wasm32 compiled with panic=abort by default
+#![feature(core_intrinsics)]
+
+// EMIT_MIR issue_104451_unwindable_intrinsics.main.AbortUnwindingCalls.after.mir
+fn main() {
+    unsafe {
+        core::intrinsics::const_eval_select((), ow_ct, ow_ct)
+    }
+}
+
+const fn ow_ct() -> ! {
+    panic!();
+}

tests/mir-opt/lower_intrinsics.assume.LowerIntrinsics.diff

@@ -11,7 +11,7 @@
           StorageLive(_1);                 // scope 1 at $DIR/lower_intrinsics.rs:+2:9: +2:38
 -         _1 = std::intrinsics::assume(const true) -> [return: bb1, unwind unreachable]; // scope 1 at $DIR/lower_intrinsics.rs:+2:9: +2:38
 -                                          // mir::Constant
--                                          // + span: $DIR/lower_intrinsics.rs:105:9: 105:32
+-                                          // + span: $DIR/lower_intrinsics.rs:106:9: 106:32
 -                                          // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(bool) {std::intrinsics::assume}, val: Value(<ZST>) }
 +         assume(const true);              // scope 1 at $DIR/lower_intrinsics.rs:+2:9: +2:38
 +         goto -> bb1;                     // scope 1 at $DIR/lower_intrinsics.rs:+2:9: +2:38

tests/mir-opt/lower_intrinsics.f_copy_nonoverlapping.LowerIntrinsics.diff

@@ -49,7 +49,7 @@
           StorageDead(_9);                 // scope 3 at $DIR/lower_intrinsics.rs:+4:90: +4:91
 -         _3 = copy_nonoverlapping::<i32>(move _4, move _8, const 0_usize) -> [return: bb1, unwind unreachable]; // scope 3 at $DIR/lower_intrinsics.rs:+4:9: +4:95
 -                                          // mir::Constant
--                                          // + span: $DIR/lower_intrinsics.rs:98:9: 98:28
+-                                          // + span: $DIR/lower_intrinsics.rs:99:9: 99:28
 -                                          // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(*const i32, *mut i32, usize) {copy_nonoverlapping::<i32>}, val: Value(<ZST>) }
 +         copy_nonoverlapping(dst = move _8, src = move _4, count = const 0_usize); // scope 3 at $DIR/lower_intrinsics.rs:+4:9: +4:95
 +         goto -> bb1;                     // scope 3 at $DIR/lower_intrinsics.rs:+4:9: +4:95

tests/mir-opt/lower_intrinsics.option_payload.LowerIntrinsics.diff

@@ -24,7 +24,7 @@
           _4 = &raw const (*_1);           // scope 1 at $DIR/lower_intrinsics.rs:+2:55: +2:56
 -         _3 = option_payload_ptr::<usize>(move _4) -> [return: bb1, unwind unreachable]; // scope 1 at $DIR/lower_intrinsics.rs:+2:18: +2:57
 -                                          // mir::Constant
--                                          // + span: $DIR/lower_intrinsics.rs:132:18: 132:54
+-                                          // + span: $DIR/lower_intrinsics.rs:133:18: 133:54
 -                                          // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(*const Option<usize>) -> *const usize {option_payload_ptr::<usize>}, val: Value(<ZST>) }
 +         _3 = &raw const (((*_4) as Some).0: usize); // scope 1 at $DIR/lower_intrinsics.rs:+2:18: +2:57
 +         goto -> bb1;                     // scope 1 at $DIR/lower_intrinsics.rs:+2:18: +2:57
@@ -37,7 +37,7 @@
           _6 = &raw const (*_2);           // scope 2 at $DIR/lower_intrinsics.rs:+3:55: +3:56
 -         _5 = option_payload_ptr::<String>(move _6) -> [return: bb2, unwind unreachable]; // scope 2 at $DIR/lower_intrinsics.rs:+3:18: +3:57
 -                                          // mir::Constant
--                                          // + span: $DIR/lower_intrinsics.rs:133:18: 133:54
+-                                          // + span: $DIR/lower_intrinsics.rs:134:18: 134:54
 -                                          // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(*const Option<String>) -> *const String {option_payload_ptr::<String>}, val: Value(<ZST>) }
 +         _5 = &raw const (((*_6) as Some).0: std::string::String); // scope 2 at $DIR/lower_intrinsics.rs:+3:18: +3:57
 +         goto -> bb2;                     // scope 2 at $DIR/lower_intrinsics.rs:+3:18: +3:57

tests/mir-opt/lower_intrinsics.read_via_copy_primitive.LowerIntrinsics.diff

@@ -13,7 +13,7 @@
           _2 = &raw const (*_1);           // scope 1 at $DIR/lower_intrinsics.rs:+1:46: +1:47
 -         _0 = read_via_copy::<i32>(move _2) -> [return: bb1, unwind unreachable]; // scope 1 at $DIR/lower_intrinsics.rs:+1:14: +1:48
 -                                          // mir::Constant
--                                          // + span: $DIR/lower_intrinsics.rs:118:14: 118:45
+-                                          // + span: $DIR/lower_intrinsics.rs:119:14: 119:45
 -                                          // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(*const i32) -> i32 {read_via_copy::<i32>}, val: Value(<ZST>) }
 +         _0 = (*_2);                      // scope 1 at $DIR/lower_intrinsics.rs:+1:14: +1:48
 +         goto -> bb1;                     // scope 1 at $DIR/lower_intrinsics.rs:+1:14: +1:48

tests/mir-opt/lower_intrinsics.read_via_copy_uninhabited.LowerIntrinsics.diff

@@ -13,7 +13,7 @@
           _2 = &raw const (*_1);           // scope 1 at $DIR/lower_intrinsics.rs:+1:46: +1:47
 -         _0 = read_via_copy::<Never>(move _2) -> unwind unreachable; // scope 1 at $DIR/lower_intrinsics.rs:+1:14: +1:48
 -                                          // mir::Constant
--                                          // + span: $DIR/lower_intrinsics.rs:123:14: 123:45
+-                                          // + span: $DIR/lower_intrinsics.rs:124:14: 124:45
 -                                          // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(*const Never) -> Never {read_via_copy::<Never>}, val: Value(<ZST>) }
 +         unreachable;                     // scope 1 at $DIR/lower_intrinsics.rs:+1:14: +1:48
       }

tests/mir-opt/lower_intrinsics.rs

@@ -1,7 +1,7 @@
 // unit-test: LowerIntrinsics
 // ignore-wasm32 compiled with panic=abort by default
 
-#![feature(core_intrinsics, intrinsics)]
+#![feature(core_intrinsics, intrinsics, rustc_attrs)]
 #![crate_type = "lib"]
 
 // EMIT_MIR lower_intrinsics.wrapping.LowerIntrinsics.diff
@@ -87,6 +87,7 @@ pub fn discriminant<T>(t: T) {
 
 extern "rust-intrinsic" {
     // Cannot use `std::intrinsics::copy_nonoverlapping` as that is a wrapper function
+    #[rustc_nounwind]
     fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize);
 }
 

tests/mir-opt/lower_intrinsics.with_overflow.LowerIntrinsics.diff

@@ -32,7 +32,7 @@
           _5 = _2;                         // scope 0 at $DIR/lower_intrinsics.rs:+1:53: +1:54
 -         _3 = add_with_overflow::<i32>(move _4, move _5) -> [return: bb1, unwind unreachable]; // scope 0 at $DIR/lower_intrinsics.rs:+1:14: +1:55
 -                                          // mir::Constant
--                                          // + span: $DIR/lower_intrinsics.rs:111:14: 111:49
+-                                          // + span: $DIR/lower_intrinsics.rs:112:14: 112:49
 -                                          // + literal: Const { ty: extern "rust-intrinsic" fn(i32, i32) -> (i32, bool) {add_with_overflow::<i32>}, val: Value(<ZST>) }
 +         _3 = CheckedAdd(move _4, move _5); // scope 0 at $DIR/lower_intrinsics.rs:+1:14: +1:55
 +         goto -> bb1;                     // scope 0 at $DIR/lower_intrinsics.rs:+1:14: +1:55
@@ -48,7 +48,7 @@
           _8 = _2;                         // scope 1 at $DIR/lower_intrinsics.rs:+2:53: +2:54
 -         _6 = sub_with_overflow::<i32>(move _7, move _8) -> [return: bb2, unwind unreachable]; // scope 1 at $DIR/lower_intrinsics.rs:+2:14: +2:55
 -                                          // mir::Constant
--                                          // + span: $DIR/lower_intrinsics.rs:112:14: 112:49
+-                                          // + span: $DIR/lower_intrinsics.rs:113:14: 113:49
 -                                          // + literal: Const { ty: extern "rust-intrinsic" fn(i32, i32) -> (i32, bool) {sub_with_overflow::<i32>}, val: Value(<ZST>) }
 +         _6 = CheckedSub(move _7, move _8); // scope 1 at $DIR/lower_intrinsics.rs:+2:14: +2:55
 +         goto -> bb2;                     // scope 1 at $DIR/lower_intrinsics.rs:+2:14: +2:55
@@ -64,7 +64,7 @@
           _11 = _2;                        // scope 2 at $DIR/lower_intrinsics.rs:+3:53: +3:54
 -         _9 = mul_with_overflow::<i32>(move _10, move _11) -> [return: bb3, unwind unreachable]; // scope 2 at $DIR/lower_intrinsics.rs:+3:14: +3:55
 -                                          // mir::Constant
--                                          // + span: $DIR/lower_intrinsics.rs:113:14: 113:49
+-                                          // + span: $DIR/lower_intrinsics.rs:114:14: 114:49
 -                                          // + literal: Const { ty: extern "rust-intrinsic" fn(i32, i32) -> (i32, bool) {mul_with_overflow::<i32>}, val: Value(<ZST>) }
 +         _9 = CheckedMul(move _10, move _11); // scope 2 at $DIR/lower_intrinsics.rs:+3:14: +3:55
 +         goto -> bb3;                     // scope 2 at $DIR/lower_intrinsics.rs:+3:14: +3:55