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, 64 insertions, 0 deletions

diff --git a/tests/codegen/patchable-function-entry/patchable-function-entry-both-flags.rs b/tests/codegen/patchable-function-entry/patchable-function-entry-both-flags.rs
new file mode 100644
index 00000000000..72204c78a49
--- /dev/null
+++ b/tests/codegen/patchable-function-entry/patchable-function-entry-both-flags.rs
@@ -0,0 +1,64 @@
+//@ compile-flags: -Z patchable-function-entry=15,10
+
+#![feature(patchable_function_entry)]
+#![crate_type = "lib"]
+
+// This should have the default, as set by the compile flags
+#[no_mangle]
+pub fn fun0() {}
+
+// The attribute should override the compile flags
+#[no_mangle]
+#[patchable_function_entry(prefix_nops = 1, entry_nops = 2)]
+pub fn fun1() {}
+
+// If we override an attribute to 0 or unset, the attribute should go away
+#[no_mangle]
+#[patchable_function_entry(entry_nops = 0)]
+pub fn fun2() {}
+
+// The attribute should override the compile flags
+#[no_mangle]
+#[patchable_function_entry(prefix_nops = 20, entry_nops = 1)]
+pub fn fun3() {}
+
+// The attribute should override the compile flags
+#[no_mangle]
+#[patchable_function_entry(prefix_nops = 2, entry_nops = 19)]
+pub fn fun4() {}
+
+// The attribute should override patchable-function-entry to 3 and
+// patchable-function-prefix to the default of 0, clearing it entirely
+#[no_mangle]
+#[patchable_function_entry(entry_nops = 3)]
+pub fn fun5() {}
+
+// The attribute should override patchable-function-prefix to 4
+// and patchable-function-entry to the default of 0, clearing it entirely
+#[no_mangle]
+#[patchable_function_entry(prefix_nops = 4)]
+pub fn fun6() {}
+
+// CHECK: @fun0() unnamed_addr #0
+// CHECK: @fun1() unnamed_addr #1
+// CHECK: @fun2() unnamed_addr #2
+// CHECK: @fun3() unnamed_addr #3
+// CHECK: @fun4() unnamed_addr #4
+// CHECK: @fun5() unnamed_addr #5
+// CHECK: @fun6() unnamed_addr #6
+
+// CHECK: attributes #0 = { {{.*}}"patchable-function-entry"="5"{{.*}}"patchable-function-prefix"="10" {{.*}} }
+// CHECK: attributes #1 = { {{.*}}"patchable-function-entry"="2"{{.*}}"patchable-function-prefix"="1" {{.*}} }
+
+// CHECK-NOT: attributes #2 = { {{.*}}patchable-function-entry{{.*}} }
+// CHECK-NOT: attributes #2 = { {{.*}}patchable-function-prefix{{.*}} }
+// CHECK: attributes #2 = { {{.*}} }
+
+// CHECK: attributes #3 = { {{.*}}"patchable-function-entry"="1"{{.*}}"patchable-function-prefix"="20" {{.*}} }
+// CHECK: attributes #4 = { {{.*}}"patchable-function-entry"="19"{{.*}}"patchable-function-prefix"="2" {{.*}} }
+
+// CHECK: attributes #5 = { {{.*}}"patchable-function-entry"="3"{{.*}} }
+// CHECK-NOT: attributes #5 = { {{.*}}patchable-function-prefix{{.*}} }
+
+// CHECK: attributes #6 = { {{.*}}"patchable-function-prefix"="4"{{.*}} }
+// CHECK-NOT: attributes #6 = { {{.*}}patchable-function-entry{{.*}} }