Auto merge of #99476 - dpaoliello:rawdylibvectorcall, r=michaelwoerister

Add tests for raw-dylib with vectorcall, and fix vectorcall code generation

* Adds tests for using `raw-dylib` (#58713) with `vectorcall`.
* Fixed code generation for `vectorcall` (parameters have to be marked with `InReg`, just like `fastcall`).
* Enabled running the `raw-dylib` `fastcall` tests when using MSVC (since I had to add support in the test for running MSVC-only tests since GCC doesn't support `vectorcall`).

compiler/rustc_target/src/abi/call/mod.rs

@@ -669,8 +669,10 @@ impl<'a, Ty> FnAbi<'a, Ty> {
 
         match &cx.target_spec().arch[..] {
             "x86" => {
-                let flavor = if let spec::abi::Abi::Fastcall { .. } = abi {
-                    x86::Flavor::Fastcall
+                let flavor = if let spec::abi::Abi::Fastcall { .. }
+                | spec::abi::Abi::Vectorcall { .. } = abi
+                {
+                    x86::Flavor::FastcallOrVectorcall
                 } else {
                     x86::Flavor::General
                 };

compiler/rustc_target/src/abi/call/x86.rs

@@ -5,7 +5,7 @@ use crate::spec::HasTargetSpec;
 #[derive(PartialEq)]
 pub enum Flavor {
     General,
-    Fastcall,
+    FastcallOrVectorcall,
 }
 
 pub fn compute_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>, flavor: Flavor)
@@ -60,9 +60,9 @@ where
         }
     }
 
-    if flavor == Flavor::Fastcall {
+    if flavor == Flavor::FastcallOrVectorcall {
         // Mark arguments as InReg like clang does it,
-        // so our fastcall is compatible with C/C++ fastcall.
+        // so our fastcall/vectorcall is compatible with C/C++ fastcall/vectorcall.
 
         // Clang reference: lib/CodeGen/TargetInfo.cpp
         // See X86_32ABIInfo::shouldPrimitiveUseInReg(), X86_32ABIInfo::updateFreeRegs()