Rollup merge of #132310 - jieyouxu:max-llvm-version, r=onur-ozkan

compiletest: add `max-llvm-major-version` directive

To complement existing `min-llvm-version` so contributors don't have to use `ignore-llvm-version: 20 - 99` to emulate `max-llvm-major-version: 19`.

Closes #132305.
cc `@workingjubilee` who suggested this.

### Implementation steps

- [x] 1. Implement the directive (this PR)
- [x] 2. Open an accompanying dev-guide PR to describe the directive (rust-lang/rustc-dev-guide#2129)

r? bootstrap

Author: GuillaumeGomez

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

@@ -120,6 +120,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "incremental",
     "known-bug",
     "llvm-cov-flags",
+    "max-llvm-major-version",
     "min-cdb-version",
     "min-gdb-version",
     "min-lldb-version",

src/tools/compiletest/src/header.rs

@@ -1546,6 +1546,20 @@ fn ignore_llvm(config: &Config, line: &str) -> IgnoreDecision {
                     ),
                 };
             }
+        } else if let Some(version_string) =
+            config.parse_name_value_directive(line, "max-llvm-major-version")
+        {
+            let max_version = extract_llvm_version(&version_string);
+            // Ignore if actual major version is larger than the maximum required major version.
+            if actual_version.major > max_version.major {
+                return IgnoreDecision::Ignore {
+                    reason: format!(
+                        "ignored when the LLVM version ({actual_version}) is newer than major\
+                        version {}",
+                        max_version.major
+                    ),
+                };
+            }
         } else if let Some(version_string) =
             config.parse_name_value_directive(line, "min-system-llvm-version")
         {

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

@@ -299,6 +299,15 @@ fn llvm_version() {
 
     let config: Config = cfg().llvm_version("10.6.2").build();
     assert!(!check_ignore(&config, "//@ exact-llvm-major-version: 10"));
+
+    let config: Config = cfg().llvm_version("19.0.0").build();
+    assert!(!check_ignore(&config, "//@ max-llvm-major-version: 19"));
+
+    let config: Config = cfg().llvm_version("19.1.2").build();
+    assert!(!check_ignore(&config, "//@ max-llvm-major-version: 19"));
+
+    let config: Config = cfg().llvm_version("20.0.0").build();
+    assert!(check_ignore(&config, "//@ max-llvm-major-version: 19"));
 }
 
 #[test]

tests/assembly/riscv-soft-abi-with-float-features.rs

@@ -2,7 +2,7 @@
 //@ compile-flags: --target riscv64imac-unknown-none-elf -Ctarget-feature=+f,+d
 //@ needs-llvm-components: riscv
 //@ revisions: LLVM-PRE-20 LLVM-POST-20
-//@ [LLVM-PRE-20] ignore-llvm-version: 20 - 99
+//@ [LLVM-PRE-20] max-llvm-major-version: 19
 //@ [LLVM-POST-20] min-llvm-version: 20
 
 #![feature(no_core, lang_items, f16)]

tests/assembly/x86_64-cmp.rs

@@ -1,7 +1,7 @@
 //@ revisions: DEBUG LLVM-PRE-20-OPTIM LLVM-20-OPTIM
 //@ [DEBUG] compile-flags: -C opt-level=0
 //@ [LLVM-PRE-20-OPTIM] compile-flags: -C opt-level=3
-//@ [LLVM-PRE-20-OPTIM] ignore-llvm-version: 20 - 99
+//@ [LLVM-PRE-20-OPTIM] max-llvm-major-version: 19
 //@ [LLVM-20-OPTIM] compile-flags: -C opt-level=3
 //@ [LLVM-20-OPTIM] min-llvm-version: 20
 //@ assembly-output: emit-asm

tests/codegen/branch-protection-old-llvm.rs

@@ -7,7 +7,7 @@
 //@ [LEAF] compile-flags: -Z branch-protection=pac-ret,leaf
 //@ [BKEY] compile-flags: -Z branch-protection=pac-ret,b-key
 //@ compile-flags: --target aarch64-unknown-linux-gnu
-//@ ignore-llvm-version: 19 - 99
+//@ max-llvm-major-version: 18
 
 #![crate_type = "lib"]
 #![feature(no_core, lang_items)]

tests/codegen/call-metadata.rs

@@ -2,7 +2,7 @@
 // scalar value.
 
 //@ compile-flags: -O -C no-prepopulate-passes
-//@ ignore-llvm-version: 19 - 99
+//@ max-llvm-major-version: 18
 
 #![crate_type = "lib"]
 

tests/codegen/integer-cmp.rs

@@ -3,7 +3,7 @@
 
 //@ revisions: llvm-pre-20 llvm-20
 //@ [llvm-20] min-llvm-version: 20
-//@ [llvm-pre-20] ignore-llvm-version: 20 - 99
+//@ [llvm-pre-20] max-llvm-major-version: 19
 //@ compile-flags: -C opt-level=3
 
 #![crate_type = "lib"]