wip hotpatch attribute always on x86, missing hotpatch debuginfo for arm

Author: nebulark

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -341,7 +341,8 @@ pub fn from_fn_attrs<'ll, 'tcx>(
         to_add.push(llvm::CreateAttrString(cx.llcx, "use-sample-profile"));
     }
 
-    if cx.sess().opts.unstable_opts.ms_hotpatch && cx.sess().target.is_x86() && cx.sess().target.is_like_msvc {
+    // patchable-function is only implemented on x86 on LLVM
+    if cx.sess().opts.unstable_opts.ms_hotpatch && cx.sess().target.is_x86() {
         to_add.push(llvm::CreateAttrStringValue(cx.llcx, "patchable-function", "prologue-short-redirect"));
     }
 

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -220,7 +220,7 @@ pub fn target_machine_factory(
     let use_init_array =
         !sess.opts.unstable_opts.use_ctors_section.unwrap_or(sess.target.use_ctors_section);
 
-    let use_hotpatch = sess.opts.unstable_opts.ms_hotpatch && sess.target.is_x86() && sess.target.is_like_msvc;
+    let use_hotpatch = sess.opts.unstable_opts.ms_hotpatch && sess.target.is_x86();
 
     let path_mapping = sess.source_map().path_mapping().clone();
 

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -2347,17 +2347,6 @@ fn add_order_independent_options(
 
     add_link_script(cmd, sess, tmpdir, crate_type);
 
-    if sess.opts.unstable_opts.ms_hotpatch && sess.target.is_x86() && sess.target.is_like_msvc {
-        // when using hotpatch also automatically instruct the linker to pad the functions
-        // so there is space for a absolute jump instructions
-        match flavor {
-            LinkerFlavor::Msvc(_) => {
-                cmd.arg("-functionpadmin");
-            },
-            _ => (),
-        }
-    }
-
     if sess.target.os == "fuchsia"
         && crate_type == CrateType::Executable
         && !matches!(flavor, LinkerFlavor::Gnu(Cc::Yes, _))

compiler/rustc_target/src/spec/mod.rs

@@ -1911,7 +1911,6 @@ impl Target {
         Ok(dl)
     }
     pub fn is_x86(&self) -> bool {
-        // ["x86", "x86_64"].contains(&self.arch.as_ref())
         ["x86", "x86_64"].contains(&&self.arch[..])
     }
 }

tests/codegen/ms-hotpatch.rs

@@ -0,0 +1,9 @@
+//@ compile-flags: -Z ms-hotpatch
+
+#![crate_type = "lib"]
+
+
+pub fn foo() {}
+
+// CHECK: @foo() unnamed_addr #0
+// CHECK: attributes #0 = { {{.*}} "patchable-function"="prologue-short-redirect" {{.*}}}