Added tests

Author: fneddy

compiler/rustc_interface/src/errors.rs

@@ -114,6 +114,13 @@ pub struct IgnoringOutDir;
 #[diag("can't use option `-o` or `--emit` to write multiple output types to stdout")]
 pub struct MultipleOutputTypesToStdout;
 
+#[derive(Diagnostic)]
+#[diag("packedstack with backchain needs softfloat")]
+#[note(
+    "enabling both `packedstack` and `backchain` attributes is incompatible with the default s390x target. Switch to s390x-unknown-none-softfloat if you need both attributes!"
+)]
+pub struct PackedStackBackchainNeedsSoftfloat;
+
 #[derive(Diagnostic)]
 #[diag(
     "target feature `{$feature}` must be {$enabled} to ensure that the ABI of the current target can be implemented correctly"

compiler/rustc_interface/src/util.rs

@@ -25,7 +25,7 @@ use rustc_session::{EarlyDiagCtxt, Session, filesearch};
 use rustc_span::edition::Edition;
 use rustc_span::source_map::SourceMapInputs;
 use rustc_span::{SessionGlobals, Symbol, sym};
-use rustc_target::spec::Target;
+use rustc_target::spec::{Abi, Arch, Target};
 use tracing::info;
 
 use crate::errors;
@@ -96,6 +96,16 @@ pub(crate) fn check_abi_required_features(sess: &Session) {
             sess.dcx().emit_warn(errors::AbiRequiredTargetFeature { feature, enabled: "disabled" });
         }
     }
+
+    // we need to have access to the complete constructed `target` and the session options.
+    // this is the first place in the `run_compiler` flow where all this is available
+    if sess.target.arch == Arch::S390x
+        && sess.opts.unstable_opts.packed_stack
+        && sess.unstable_target_features.contains(&Symbol::intern(&"backchain"))
+        && sess.target.abi != Abi::SoftFloat
+    {
+        sess.dcx().emit_err(errors::PackedStackBackchainNeedsSoftfloat);
+    }
 }
 
 pub static STACK_SIZE: OnceLock<usize> = OnceLock::new();

compiler/rustc_target/src/spec/mod.rs

@@ -3258,16 +3258,6 @@ impl Target {
                     ));
                 }
             }
-            // If both `packed-stack` and `backchain` are set we need to use soft-float ABI.
-            if self.arch == Arch::S390x
-                && features_enabled.contains("packed-stack")
-                && features_enabled.contains("backchain")
-                && !matches!(self.abi, Abi::SoftFloat)
-            {
-                return Err(format!(
-                    "Enabling both `packed-stack` and `backchain` attributes is incompatible with the default s390x target. Switch to s390x-unknown-none-softfloat if you need both attributes."
-                ));
-            }
         }
 
         Ok(())

tests/assembly-llvm/s390x-packedstack-toggle.rs

@@ -0,0 +1,37 @@
+//@ add-minicore
+//@ revisions: enable-packedstack default-packedstack
+//@ assembly-output: emit-asm
+//@ compile-flags: -Copt-level=3 --crate-type=lib --target=s390x-unknown-linux-gnu -Cforce-unwind-tables=no
+//@ needs-llvm-components: systemz
+//@[enable-packedstack] compile-flags: -Zpacked-stack
+#![feature(no_core, lang_items)]
+#![no_std]
+#![no_core]
+
+extern crate minicore;
+use minicore::*;
+
+extern "C" {
+    fn extern_func() -> i32;
+}
+
+// CHECK-LABEL: test_packedstack
+#[no_mangle]
+extern "C" fn test_packedstack() -> i32 {
+    // test the creation of call stack with and without packed-stack
+
+    // without packed-stack we always reserve a least the maximal space of 160 bytes
+    // default-packedstack: stmg %r14, %r15, 112(%r15)
+    // default-packedstack-NEXT: aghi %r15, -160
+    // default-packedstack-NEXT: brasl %r14, extern_func
+
+    // with packed-stack only the actually needed registers are reserved on the stack
+    // enable-packedstack: stmg %r14, %r15, 144(%r15)
+    // enable-packedstack-NEXT: aghi %r15, -16
+    // enable-packedstack-NEXT: brasl %r14, extern_func
+    unsafe {
+        extern_func();
+    }
+    1
+    // CHECK: br %r{{.*}}
+}

tests/codegen-llvm/packedstack.rs

@@ -0,0 +1,16 @@
+//@ add-minicore
+//@ compile-flags: -Copt-level=3 --crate-type=lib --target=s390x-unknown-linux-gnu -Zpacked-stack
+//@ needs-llvm-components: systemz
+#![crate_type = "lib"]
+#![feature(no_core, lang_items)]
+#![no_core]
+
+extern crate minicore;
+use minicore::*;
+
+#[no_mangle]
+
+pub fn test_packedstack() {
+    // CHECK: @test_packedstack() unnamed_addr #0
+}
+// CHECK: attributes #0 = { {{.*}}"packed-stack"{{.*}} }

tests/ui/README.md

@@ -1070,6 +1070,10 @@ Exercises operator overloading via [`std::ops`](https://doc.rust-lang.org/std/op
 
 See [`repr(packed)` | Nomicon](https://doc.rust-lang.org/nomicon/other-reprs.html#reprpacked-reprpackedn).
 
+## `tests/ui/packedstack/`
+
+Tests different combinations that `-Zpacked-stack` will affect.
+
 ## `tests/ui/panic-handler/`
 
 See [panic handler | Nomicon](https://doc.rust-lang.org/nomicon/panic-handler.html).

tests/ui/packedstack/combination.need_softfloat.stderr

@@ -0,0 +1,10 @@
+warning: unstable feature specified for `-Ctarget-feature`: `backchain`
+   |
+   = note: this feature is not stably supported; its behavior can change in the future
+
+error: packedstack with backchain needs softfloat
+   |
+   = note: enabling both `packedstack` and `backchain` attributes is incompatible with the default s390x target. Switch to s390x-unknown-none-softfloat if you need both attributes!
+
+error: aborting due to 1 previous error; 1 warning emitted
+

tests/ui/packedstack/combination.rs

@@ -0,0 +1,29 @@
+//@ revisions: wrong_arch only_packedstack need_softfloat with_softfloat
+//@ compile-flags: -Zpacked-stack --crate-type=lib
+
+//@ [wrong_arch] compile-flags: --target=x86_64-unknown-linux-gnu
+//@ [wrong_arch] needs-llvm-components: x86
+
+//@ [only_packedstack] compile-flags: --target=s390x-unknown-linux-gnu
+//@ [only_packedstack] build-pass
+//@ [only_packedstack] needs-llvm-components: systemz
+
+//@ [need_softfloat] compile-flags: -Ctarget-feature=+backchain --target=s390x-unknown-linux-gnu
+//@ [need_softfloat] check-fail
+//@ [need_softfloat] needs-llvm-components: systemz
+
+//@ [with_softfloat] compile-flags: -Ctarget-feature=+backchain
+//@ [with_softfloat] compile-flags: --target=s390x-unknown-none-softfloat
+//@ [with_softfloat] build-pass
+//@ [with_softfloat] needs-llvm-components: systemz
+
+//@ ignore-backends: gcc
+
+#![feature(no_core)]
+#![crate_type = "rlib"]
+#![no_core]
+
+//[wrong_arch]~? ERROR `-Zpacked-stack` is only supported on s390x
+//[need_softfloat]~? WARN unstable feature specified for `-Ctarget-feature`: `backchain`
+//[need_softfloat]~? ERROR packedstack with backchain needs softfloat
+//[with_softfloat]~? WARN unstable feature specified for `-Ctarget-feature`: `backchain`

tests/ui/packedstack/combination.with_softfloat.stderr

@@ -0,0 +1,6 @@
+warning: unstable feature specified for `-Ctarget-feature`: `backchain`
+   |
+   = note: this feature is not stably supported; its behavior can change in the future
+
+warning: 1 warning emitted
+

tests/ui/packedstack/combination.wrong_arch.stderr

@@ -0,0 +1,4 @@
+error: `-Zpacked-stack` is only supported on s390x
+
+error: aborting due to 1 previous error
+