Auto merge of #83271 - SparrowLii:simd_neg, r=Amanieu

Add simd_neg platform intrinsic

Stdarch needs to add simd_neg to support the implementation of vneg neon instructions. Look [here](https://github.com/rust-lang/stdarch/pull/1087)

1 files changed, 21 insertions, 2 deletions

diff --git a/compiler/rustc_codegen_llvm/src/intrinsic.rs b/compiler/rustc_codegen_llvm/src/intrinsic.rs
index f445d708c94..af366f93b91 100644
--- a/compiler/rustc_codegen_llvm/src/intrinsic.rs
+++ b/compiler/rustc_codegen_llvm/src/intrinsic.rs
@@ -1628,7 +1628,7 @@ unsupported {} from `{}` with element `{}` of size `{}` to `{}`"#,
             out_elem
         );
     }
-    macro_rules! arith {
+    macro_rules! arith_binary {
         ($($name: ident: $($($p: ident),* => $call: ident),*;)*) => {
             $(if name == sym::$name {
                 match in_elem.kind() {
@@ -1644,7 +1644,7 @@ unsupported {} from `{}` with element `{}` of size `{}` to `{}`"#,
             })*
         }
     }
-    arith! {
+    arith_binary! {
         simd_add: Uint, Int => add, Float => fadd;
         simd_sub: Uint, Int => sub, Float => fsub;
         simd_mul: Uint, Int => mul, Float => fmul;
@@ -1659,6 +1659,25 @@ unsupported {} from `{}` with element `{}` of size `{}` to `{}`"#,
         simd_fmin: Float => minnum;
 
     }
+    macro_rules! arith_unary {
+        ($($name: ident: $($($p: ident),* => $call: ident),*;)*) => {
+            $(if name == sym::$name {
+                match in_elem.kind() {
+                    $($(ty::$p(_))|* => {
+                        return Ok(bx.$call(args[0].immediate()))
+                    })*
+                    _ => {},
+                }
+                require!(false,
+                         "unsupported operation on `{}` with element `{}`",
+                         in_ty,
+                         in_elem)
+            })*
+        }
+    }
+    arith_unary! {
+        simd_neg: Int => neg, Float => fneg;
+    }
 
     if name == sym::simd_saturating_add || name == sym::simd_saturating_sub {
         let lhs = args[0].immediate();