Rollup merge of #124741 - nebulark:patchable-function-entries-pr, r=estebank,workingjubilee

patchable-function-entry: Add unstable compiler flag and attribute

Tracking issue: #123115

Add the -Z patchable-function-entry compiler flag and the #[patchable_function_entry(prefix_nops = m, entry_nops = n)] attribute.
Rebased and adjusted the canditate implementation to match changes in the RFC.

1 files changed, 39 insertions, 0 deletions

diff --git a/tests/codegen/patchable-function-entry/patchable-function-entry-no-flag.rs b/tests/codegen/patchable-function-entry/patchable-function-entry-no-flag.rs
new file mode 100644
index 00000000000..3a7078fe551
--- /dev/null
+++ b/tests/codegen/patchable-function-entry/patchable-function-entry-no-flag.rs
@@ -0,0 +1,39 @@
+#![feature(patchable_function_entry)]
+#![crate_type = "lib"]
+
+// No patchable function entry should be set
+#[no_mangle]
+pub fn fun0() {}
+
+// The attribute should work even without compiler flags
+#[no_mangle]
+#[patchable_function_entry(prefix_nops = 1, entry_nops = 2)]
+pub fn fun1() {}
+
+// The attribute should work even without compiler flags
+// and only set patchable-function-entry to 3.
+#[no_mangle]
+#[patchable_function_entry(entry_nops = 3)]
+pub fn fun2() {}
+
+// The attribute should work even without compiler flags
+// and only set patchable-function-prefix to 4.
+#[no_mangle]
+#[patchable_function_entry(prefix_nops = 4)]
+pub fn fun3() {}
+
+// CHECK: @fun0() unnamed_addr #0
+// CHECK: @fun1() unnamed_addr #1
+// CHECK: @fun2() unnamed_addr #2
+// CHECK: @fun3() unnamed_addr #3
+
+// CHECK-NOT: attributes #0 = { {{.*}}patchable-function-entry{{.*}} }
+// CHECK-NOT: attributes #0 = { {{.*}}patchable-function-prefix{{.*}} }
+
+// CHECK: attributes #1 = { {{.*}}"patchable-function-entry"="2"{{.*}}"patchable-function-prefix"="1" {{.*}} }
+
+// CHECK: attributes #2 = { {{.*}}"patchable-function-entry"="3"{{.*}} }
+// CHECK-NOT: attributes #2 = { {{.*}}patchable-function-prefix{{.*}} }
+
+// CHECK: attributes #3 = { {{.*}}"patchable-function-prefix"="4"{{.*}} }
+// CHECK-NOT: attributes #3 = { {{.*}}patchable-function-entry{{.*}} }