Add `exact-llvm-major-version` directive

src/tools/compiletest/src/directive-list.rs

@@ -25,6 +25,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "dont-check-failure-status",
     "edition",
     "error-pattern",
+    "exact-llvm-major-version",
     "exec-env",
     "failure-status",
     "filecheck-flags",

src/tools/compiletest/src/header.rs

@@ -1585,6 +1585,19 @@ fn ignore_llvm(config: &Config, line: &str) -> IgnoreDecision {
                     };
                 }
             }
+        } else if let Some(version_string) =
+            config.parse_name_value_directive(line, "exact-llvm-major-version")
+        {
+            // Syntax is "only-llvm-major-version: <version>"
+            let version = extract_llvm_version(&version_string);
+            if actual_version.major > version.major || actual_version.major < version.major {
+                return IgnoreDecision::Ignore {
+                    reason: format!(
+                        "ignored when the LLVM major version is {}, but it should be {}",
+                        actual_version.major, version.major
+                    ),
+                };
+            }
         }
     }
     IgnoreDecision::Continue

src/tools/compiletest/src/header/tests.rs

@@ -284,6 +284,15 @@ fn llvm_version() {
 
     let config: Config = cfg().llvm_version("10.0.0").build();
     assert!(!check_ignore(&config, "//@ min-llvm-version: 9.0"));
+
+    let config: Config = cfg().llvm_version("10.0.0").build();
+    assert!(check_ignore(&config, "//@ exact-llvm-major-version: 9.0"));
+
+    let config: Config = cfg().llvm_version("9.0.0").build();
+    assert!(check_ignore(&config, "//@ exact-llvm-major-version: 10.0"));
+
+    let config: Config = cfg().llvm_version("10.0.0").build();
+    assert!(!check_ignore(&config, "//@ exact-llvm-major-version: 10.0"));
 }
 
 #[test]

tests/codegen/try_question_mark_nop.rs

@@ -2,8 +2,7 @@
 //@ only-x86_64
 // FIXME: Remove the `min-llvm-version`.
 //@ revisions: NINETEEN TWENTY
-//@[NINETEEN] min-llvm-version: 19
-//@[NINETEEN] ignore-llvm-version: 20-99
+//@[NINETEEN] exact-llvm-major-version: 19
 //@[TWENTY] min-llvm-version: 20
 //@ min-llvm-version: 19