Auto merge of #146318 - matthiaskrgr:rollup-9a8s6fv, r=matthiaskrgr

Rollup of 5 pull requests

Successful merges:

 - #144549 (match clang's `va_arg` assembly on arm targets)
 - #146184 (In the rustc_llvm build script, don't consider arm64* to be 32-bit)
 - #146298 (GVN: Ensure indirect is first projection in try_as_place.)
 - #146299 (docs(std): add error docs for path canonicalize)
 - #146300 (Implement `Sum` and `Product` for `f16` and `f128`.)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_codegen_llvm/src/va_arg.rs

@@ -908,6 +908,21 @@ pub(super) fn emit_va_arg<'ll, 'tcx>(
             )
         }
         "aarch64" => emit_aapcs_va_arg(bx, addr, target_ty),
+        "arm" => {
+            // Types wider than 16 bytes are not currently supported. Clang has special logic for
+            // such types, but `VaArgSafe` is not implemented for any type that is this large.
+            assert!(bx.cx.size_of(target_ty).bytes() <= 16);
+
+            emit_ptr_va_arg(
+                bx,
+                addr,
+                target_ty,
+                PassMode::Direct,
+                SlotSize::Bytes4,
+                AllowHigherAlign::Yes,
+                ForceRightAdjust::No,
+            )
+        }
         "s390x" => emit_s390x_va_arg(bx, addr, target_ty),
         "powerpc" => emit_powerpc_va_arg(bx, addr, target_ty),
         "powerpc64" | "powerpc64le" => emit_ptr_va_arg(

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -520,7 +520,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 LocalRef::Place(va_list) => {
                     bx.va_end(va_list.val.llval);
 
-                    // Explicitly end the lifetime of the `va_list`, this matters for LLVM.
+                    // Explicitly end the lifetime of the `va_list`, improves LLVM codegen.
                     bx.lifetime_end(va_list.val.llval, va_list.layout.size);
                 }
                 _ => bug!("C-variadic function must have a `VaList` place"),

compiler/rustc_codegen_ssa/src/mir/mod.rs

@@ -438,6 +438,10 @@ fn arg_local_refs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 
             if fx.fn_abi.c_variadic && arg_index == fx.fn_abi.args.len() {
                 let va_list = PlaceRef::alloca(bx, bx.layout_of(arg_ty));
+
+                // Explicitly start the lifetime of the `va_list`, improves LLVM codegen.
+                bx.lifetime_start(va_list.val.llval, va_list.layout.size);
+
                 bx.va_start(va_list.val.llval);
 
                 return LocalRef::Place(va_list);

compiler/rustc_llvm/build.rs

@@ -254,7 +254,10 @@ fn main() {
         println!("cargo:rustc-link-lib=kstat");
     }
 
-    if (target.starts_with("arm") && !target.contains("freebsd") && !target.contains("ohos"))
+    if (target.starts_with("arm")
+        && !target.starts_with("arm64")
+        && !target.contains("freebsd")
+        && !target.contains("ohos"))
         || target.starts_with("mips-")
         || target.starts_with("mipsel-")
         || target.starts_with("powerpc-")

compiler/rustc_mir_transform/src/gvn.rs

@@ -1644,6 +1644,11 @@ impl<'tcx> VnState<'_, 'tcx> {
                 let place =
                     Place { local, projection: self.tcx.mk_place_elems(projection.as_slice()) };
                 return Some(place);
+            } else if projection.last() == Some(&PlaceElem::Deref) {
+                // `Deref` can only be the first projection in a place.
+                // If we are here, we failed to find a local, and we already have a `Deref`.
+                // Trying to add projections will only result in an ill-formed place.
+                return None;
             } else if let Value::Projection(pointer, proj) = *self.get(index)
                 && (allow_complex_projection || proj.is_stable_offset())
                 && let Some(proj) = self.try_as_place_elem(self.ty(index), proj, loc)

library/core/src/iter/traits/accum.rs

@@ -203,7 +203,7 @@ macro_rules! float_sum_product {
 
 integer_sum_product! { i8 i16 i32 i64 i128 isize u8 u16 u32 u64 u128 usize }
 saturating_integer_sum_product! { u8 u16 u32 u64 u128 usize }
-float_sum_product! { f32 f64 }
+float_sum_product! { f16 f32 f64 f128 }
 
 #[stable(feature = "iter_arith_traits_result", since = "1.16.0")]
 impl<T, U, E> Sum<Result<U, E>> for Result<T, E>

library/std/src/path.rs

@@ -3037,6 +3037,14 @@ impl Path {
     ///
     /// This is an alias to [`fs::canonicalize`].
     ///
+    /// # Errors
+    ///
+    /// This method will return an error in the following situations, but is not
+    /// limited to just these cases:
+    ///
+    /// * `path` does not exist.
+    /// * A non-final component in path is not a directory.
+    ///
     /// # Examples
     ///
     /// ```no_run

tests/assembly-llvm/c-variadic-arm.rs

@@ -0,0 +1,26 @@
+//@ assembly-output: emit-asm
+//@ compile-flags: -Copt-level=3
+//@ only-arm
+//@ ignore-thumb
+#![no_std]
+#![crate_type = "lib"]
+#![feature(c_variadic)]
+
+// Check that the assembly that rustc generates matches what clang emits.
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn variadic(a: f64, mut args: ...) -> f64 {
+    // CHECK-LABEL: variadic
+    // CHECK: sub sp, sp, #12
+
+    // CHECK: vldr
+    let b = args.arg::<f64>();
+    // CHECK: vldr
+    let c = args.arg::<f64>();
+
+    // CHECK: vadd.f64
+    // CHECK: vadd.f64
+    a + b + c
+
+    // CHECK: add sp, sp, #12
+}

tests/codegen-llvm/c-variadic-lifetime.rs

@@ -0,0 +1,21 @@
+//@ add-core-stubs
+//@ compile-flags: -Copt-level=3
+#![feature(c_variadic)]
+#![crate_type = "lib"]
+
+// Check that `%args` explicitly has its lifetime start and end. Being explicit can improve
+// instruction and register selection, see e.g. https://github.com/rust-lang/rust/pull/144549
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn variadic(a: f64, mut args: ...) -> f64 {
+    // CHECK: call void @llvm.lifetime.start.p0(i64 {{[0-9]+}}, ptr nonnull %args)
+    // CHECK: call void @llvm.va_start.p0(ptr nonnull %args)
+
+    let b = args.arg::<f64>();
+    let c = args.arg::<f64>();
+
+    a + b + c
+
+    // CHECK: call void @llvm.va_end.p0(ptr nonnull %args)
+    // CHECK: call void @llvm.lifetime.end.p0(i64 {{[0-9]+}}, ptr nonnull %args)
+}