test #[naked] with #[link_section = "..."] on windows

compiler/rustc_codegen_ssa/src/mir/naked_asm.rs

@@ -141,8 +141,14 @@ fn prefix_and_suffix<'tcx>(
     let attrs = tcx.codegen_instance_attrs(instance.def);
     let link_section = attrs.link_section.map(|symbol| symbol.as_str().to_string());
 
-    // If no alignment is specified, an alignment of 4 bytes is used.
-    let align_bytes = attrs.alignment.map(|a| a.bytes()).unwrap_or(4);
+    // Pick a default alignment when the alignment is not explicitly specified.
+    let align_bytes = match attrs.alignment {
+        Some(align) => align.bytes(),
+        None => match asm_binary_format {
+            BinaryFormat::Coff => 16,
+            _ => 4,
+        },
+    };
 
     // In particular, `.arm` can also be written `.code 32` and `.thumb` as `.code 16`.
     let (arch_prefix, arch_suffix) = if is_arm {
@@ -267,19 +273,18 @@ fn prefix_and_suffix<'tcx>(
             }
         }
         BinaryFormat::Coff => {
-            let section = link_section.unwrap_or_else(|| format!(".text.{asm_name}"));
-            writeln!(begin, ".pushsection {},\"xr\"", section).unwrap();
-            writeln!(begin, ".balign {align_bytes}").unwrap();
-            write_linkage(&mut begin).unwrap();
             writeln!(begin, ".def {asm_name}").unwrap();
             writeln!(begin, ".scl 2").unwrap();
             writeln!(begin, ".type 32").unwrap();
             writeln!(begin, ".endef").unwrap();
+
+            let section = link_section.unwrap_or_else(|| format!(".text.{asm_name}"));
+            writeln!(begin, ".pushsection {},\"xr\"", section).unwrap();
+            write_linkage(&mut begin).unwrap();
+            writeln!(begin, ".balign {align_bytes}").unwrap();
             writeln!(begin, "{asm_name}:").unwrap();
 
             writeln!(end).unwrap();
-            writeln!(end, ".Lfunc_end_{asm_name}:").unwrap();
-            writeln!(end, ".popsection").unwrap();
             if !arch_suffix.is_empty() {
                 writeln!(end, "{}", arch_suffix).unwrap();
             }

tests/assembly-llvm/naked-functions/link-section-windows.rs

@@ -0,0 +1,49 @@
+//@ revisions: windows-x86-gnu windows-x86-msvc
+//@ add-minicore
+//@ assembly-output: emit-asm
+//
+//@[windows-x86-gnu] compile-flags: --target x86_64-pc-windows-gnu
+//@[windows-x86-gnu] needs-llvm-components: x86
+//
+//@[windows-x86-msvc] compile-flags: --target x86_64-pc-windows-msvc
+//@[windows-x86-msvc] needs-llvm-components: x86
+
+#![crate_type = "lib"]
+#![feature(no_core)]
+#![no_core]
+
+// Tests that naked and non-naked functions emit the same directives when the function uses
+// `#[link_section = "..."]`.
+
+extern crate minicore;
+use minicore::*;
+
+#[unsafe(naked)]
+#[unsafe(no_mangle)]
+#[unsafe(link_section = "naked")]
+extern "C" fn naked_ret() {
+    // CHECK: .def    naked_ret;
+    // CHECK-NEXT: .scl    2;
+    // CHECK-NEXT: .type   32;
+    // CHECK-NEXT: .endef
+    // CHECK-NEXT: .section    naked,"xr"
+    // CHECK-NEXT: .globl  naked_ret
+    // CHECK-NEXT: .p2align    4
+    // CHECK-NEXT: naked_ret:
+    // CHECK-NEXT: retq
+    naked_asm!("ret")
+}
+
+#[unsafe(no_mangle)]
+#[unsafe(link_section = "regular")]
+extern "C" fn regular_ret() {
+    // CHECK: .def    regular_ret;
+    // CHECK-NEXT: .scl    2;
+    // CHECK-NEXT: .type   32;
+    // CHECK-NEXT: .endef
+    // CHECK-NEXT: .section    regular,"xr"
+    // CHECK-NEXT: .globl  regular_ret
+    // CHECK-NEXT: .p2align    4
+    // CHECK-NEXT: regular_ret:
+    // CHECK-NEXT: retq
+}

tests/codegen-llvm/naked-fn/generics.rs

@@ -19,11 +19,11 @@ fn test(x: u64) {
     foo.trait_method();
 }
 
-// CHECK: .balign 4
+// CHECK: .balign
 // CHECK: add rax, 1
 // CHECK: add rax, 42
 
-// CHECK: .balign 4
+// CHECK: .balign
 // CHECK: add rax, 2
 // CHECK: add rax, 42
 
@@ -52,7 +52,7 @@ fn invert(self) -> Self {
     }
 }
 
-// CHECK: .balign 4
+// CHECK: .balign
 // CHECK-LABEL: generic_function:
 // CHECK: call
 // CHECK: ret
@@ -71,7 +71,7 @@ pub extern "C" fn generic_function<T: Invert>(x: i64) -> i64 {
 #[repr(transparent)]
 struct Foo(u64);
 
-// CHECK: .balign 4
+// CHECK: .balign
 // CHECK-LABEL: method:
 // CHECK: mov rax, rdi
 
@@ -83,7 +83,7 @@ extern "C" fn method(self) -> u64 {
     }
 }
 
-// CHECK: .balign 4
+// CHECK: .balign
 // CHECK-LABEL: trait_method:
 // CHECK: mov rax, rdi
 
@@ -99,7 +99,7 @@ extern "C" fn trait_method(self) -> u64 {
     }
 }
 
-// CHECK: .balign 4
+// CHECK: .balign
 // CHECK-LABEL: naked_with_args_and_return:
 // CHECK: lea rax, [rdi + rsi]
 

tests/codegen-llvm/naked-fn/naked-functions.rs

@@ -19,17 +19,15 @@
 extern crate minicore;
 use minicore::*;
 
-// linux,win: .intel_syntax
+// linux,win_x86,win_i686: .intel_syntax
 //
 // linux:    .pushsection .text.naked_empty,\22ax\22, @progbits
 // macos:    .pushsection __TEXT,__text,regular,pure_instructions
-// win_x86:  .pushsection .text.naked_empty,\22xr\22
-// win_i686: .pushsection .text._naked_empty,\22xr\22
 // thumb:    .pushsection .text.naked_empty,\22ax\22, %progbits
 //
-// CHECK: .balign 4
+// linux, macos, thumb: .balign 4
 //
-// linux,win,thumb: .globl naked_empty
+// linux,thumb: .globl naked_empty
 // macos: .globl _naked_empty
 //
 // CHECK-NOT: .private_extern
@@ -44,20 +42,28 @@
 // win_x86,win_i686: .type 32
 // win_x86,win_i686: .endef
 //
+// win_x86:  .pushsection .text.naked_empty,\22xr\22
+// win_i686: .pushsection .text._naked_empty,\22xr\22
+//
+// win_x86: .globl naked_empty
+// win_i686: .globl _naked_empty
+//
+// win_x86,win_i686: .balign 16
+//
 // thumb: .type naked_empty, %function
 // thumb: .thumb
 // thumb: .thumb_func
 //
 // CHECK-LABEL: naked_empty:
 //
-// linux,macos,win: ret
+// linux,macos,win_x86,win_x86: ret
 // thumb: bx lr
 //
-// CHECK: .popsection
+// linux,macos,thumb: .popsection
 //
 // thumb: .thumb
 //
-// linux,win: .att_syntax
+// linux,win_x86,win_i686: .att_syntax
 
 #[no_mangle]
 #[unsafe(naked)]
@@ -72,17 +78,15 @@ pub extern "C" fn naked_empty() {
     }
 }
 
-// linux,win: .intel_syntax
+// linux,win_x86,win_i686: .intel_syntax
 //
 // linux:    .pushsection .text.naked_with_args_and_return,\22ax\22, @progbits
 // macos:    .pushsection __TEXT,__text,regular,pure_instructions
-// win_x86:  .pushsection .text.naked_with_args_and_return,\22xr\22
-// win_i686: .pushsection .text._naked_with_args_and_return,\22xr\22
 // thumb:    .pushsection .text.naked_with_args_and_return,\22ax\22, %progbits
 //
-// CHECK: .balign 4
+// linux, macos, thumb: .balign 4
 //
-// linux,win,thumb: .globl naked_with_args_and_return
+// linux,thumb: .globl naked_with_args_and_return
 // macos: .globl _naked_with_args_and_return
 //
 // CHECK-NOT: .private_extern
@@ -97,6 +101,14 @@ pub extern "C" fn naked_empty() {
 // win_x86,win_i686: .type 32
 // win_x86,win_i686: .endef
 //
+// win_x86:  .pushsection .text.naked_with_args_and_return,\22xr\22
+// win_i686: .pushsection .text._naked_with_args_and_return,\22xr\22
+//
+// win_x86: .globl naked_with_args_and_return
+// win_i686: .globl _naked_with_args_and_return
+//
+// win_x86,win_i686: .balign 16
+//
 // thumb: .type naked_with_args_and_return, %function
 // thumb: .thumb
 // thumb: .thumb_func
@@ -107,14 +119,14 @@ pub extern "C" fn naked_empty() {
 // macos: add x0, x0, x1
 // thumb: adds r0, r0, r1
 //
-// linux,macos,win: ret
+// linux,macos,win_x86,win_i686: ret
 // thumb: bx lr
 //
-// CHECK: .popsection
+// linux,macos,thumb: .popsection
 //
 // thumb: .thumb
 //
-// linux,win: .att_syntax
+// linux,win_x86,win_i686: .att_syntax
 
 #[no_mangle]
 #[unsafe(naked)]