Enable thumbv7a-pc-windows-msvc target build end to end in rust/master

src/librustc_codegen_llvm/back/write.rs

@@ -795,10 +795,10 @@ fn create_msvc_imps(
         return
     }
     // The x86 ABI seems to require that leading underscores are added to symbol
-    // names, so we need an extra underscore on 32-bit. There's also a leading
+    // names, so we need an extra underscore on x86. There's also a leading
     // '\x01' here which disables LLVM's symbol mangling (e.g., no extra
     // underscores added in front).
-    let prefix = if cgcx.target_pointer_width == "32" {
+    let prefix = if cgcx.target_arch == "x86" {
         "\x01__imp__"
     } else {
         "\x01__imp_"

src/librustc_codegen_ssa/back/write.rs

@@ -248,6 +248,7 @@ pub struct CodegenContext<B: WriteBackendMethods> {
     pub tm_factory: TargetMachineFactory<B>,
     pub msvc_imps_needed: bool,
     pub target_pointer_width: String,
+    pub target_arch: String,
     pub debuginfo: config::DebugInfo,
 
     // Number of cgus excluding the allocator/metadata modules
@@ -1103,6 +1104,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
         total_cgus,
         msvc_imps_needed: msvc_imps_needed(tcx),
         target_pointer_width: tcx.sess.target.target.target_pointer_width.clone(),
+        target_arch: tcx.sess.target.target.arch.clone(),
         debuginfo: tcx.sess.opts.debuginfo,
         assembler_cmd,
     };

src/libtest/lib.rs

@@ -37,12 +37,13 @@ extern crate libc;
 use term;
 
 // FIXME(#54291): rustc and/or LLVM don't yet support building with panic-unwind
-//                on aarch64-pc-windows-msvc, so we don't link libtest against
-//                libunwind (for the time being), even though it means that
-//                libtest won't be fully functional on this platform.
+//                on aarch64-pc-windows-msvc, or thumbv7a-pc-windows-msvc
+//                so we don't link libtest against libunwind (for the time being)
+//                even though it means that libtest won't be fully functional on
+//                these platforms.
 //
 // See also: https://github.com/rust-lang/rust/issues/54190#issuecomment-422904437
-#[cfg(not(all(windows, target_arch = "aarch64")))]
+#[cfg(not(all(windows, any(target_arch = "aarch64", target_arch = "arm"))))]
 extern crate panic_unwind;
 
 pub use self::ColorConfig::*;