From 57d24a34946813a06e30be2046aad78c65d84ca0 Mon Sep 17 00:00:00 2001
From: Tsukasa OI <floss_rust@irq.a4lg.com>
Date: Mon, 24 Mar 2025 00:23:46 +0000
Subject: [PATCH] rustc_target: RISC-V "Zfinx" is incompatible with
 {ILP32,LP64}[FD] ABIs

Because RISC-V Calling Conventions note that:

> This means code targeting the Zfinx extension always uses the ILP32,
> ILP32E or LP64 integer calling-convention only ABIs as there is no
> dedicated hardware floating-point register file.

{ILP32,LP64}[FD] ABIs with hardware floating-point calling conventions
are incompatible with the "Zfinx" extension.

This commit adds "zfinx" to the incompatible feature list to those ABIs
and tests whether trying to add "zdinx" (that is analogous to "zfinx" but
in double-precision) on a LP64D ABI configuration results in an error
(it also tests extension implication; "Zdinx" requires "Zfinx" extension).

Link: RISC-V psABI specification version 1.0
<https://github.com/riscv-non-isa/riscv-elf-psabi-doc/releases/tag/v1.0>
---
 compiler/rustc_target/src/target_features.rs         |  8 ++++----
 ...bidden-hardfloat-target-feature-attribute-e-d.rs} |  0
 ...en-hardfloat-target-feature-attribute-e-d.stderr} |  2 +-
 ...den-hardfloat-target-feature-attribute-f-zfinx.rs | 12 ++++++++++++
 ...hardfloat-target-feature-attribute-f-zfinx.stderr |  8 ++++++++
 5 files changed, 25 insertions(+), 5 deletions(-)
 rename tests/ui/target-feature/{forbidden-hardfloat-target-feature-attribute.rs => forbidden-hardfloat-target-feature-attribute-e-d.rs} (100%)
 rename tests/ui/target-feature/{forbidden-hardfloat-target-feature-attribute.stderr => forbidden-hardfloat-target-feature-attribute-e-d.stderr} (77%)
 create mode 100644 tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute-f-zfinx.rs
 create mode 100644 tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute-f-zfinx.stderr

diff --git a/compiler/rustc_target/src/target_features.rs b/compiler/rustc_target/src/target_features.rs
index b4ec1879fed5c..c305886ca0e16 100644
--- a/compiler/rustc_target/src/target_features.rs
+++ b/compiler/rustc_target/src/target_features.rs
@@ -953,12 +953,12 @@ impl Target {
                 // about what the intended ABI is.
                 match &*self.llvm_abiname {
                     "ilp32d" | "lp64d" => {
-                        // Requires d (which implies f), incompatible with e.
-                        FeatureConstraints { required: &["d"], incompatible: &["e"] }
+                        // Requires d (which implies f), incompatible with e and zfinx.
+                        FeatureConstraints { required: &["d"], incompatible: &["e", "zfinx"] }
                     }
                     "ilp32f" | "lp64f" => {
-                        // Requires f, incompatible with e.
-                        FeatureConstraints { required: &["f"], incompatible: &["e"] }
+                        // Requires f, incompatible with e and zfinx.
+                        FeatureConstraints { required: &["f"], incompatible: &["e", "zfinx"] }
                     }
                     "ilp32" | "lp64" => {
                         // Requires nothing, incompatible with e.
diff --git a/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.rs b/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute-e-d.rs
similarity index 100%
rename from tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.rs
rename to tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute-e-d.rs
diff --git a/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.stderr b/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute-e-d.stderr
similarity index 77%
rename from tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.stderr
rename to tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute-e-d.stderr
index bfe767e5ffb07..84d27463b38cd 100644
--- a/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute.stderr
+++ b/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute-e-d.stderr
@@ -1,5 +1,5 @@
 error: target feature `d` cannot be enabled with `#[target_feature]`: this feature is incompatible with the target ABI
-  --> $DIR/forbidden-hardfloat-target-feature-attribute.rs:10:18
+  --> $DIR/forbidden-hardfloat-target-feature-attribute-e-d.rs:10:18
    |
 LL | #[target_feature(enable = "d")]
    |                  ^^^^^^^^^^^^
diff --git a/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute-f-zfinx.rs b/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute-f-zfinx.rs
new file mode 100644
index 0000000000000..d74f4a1d4b170
--- /dev/null
+++ b/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute-f-zfinx.rs
@@ -0,0 +1,12 @@
+//! Ensure ABI-incompatible features cannot be enabled via `#[target_feature]`.
+//@ compile-flags: --target=riscv64gc-unknown-linux-gnu --crate-type=lib
+//@ needs-llvm-components: riscv
+#![feature(no_core, lang_items, riscv_target_feature)]
+#![no_core]
+
+#[lang = "sized"]
+pub trait Sized {}
+
+#[target_feature(enable = "zdinx")]
+//~^ERROR: cannot be enabled with
+pub unsafe fn my_fun() {}
diff --git a/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute-f-zfinx.stderr b/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute-f-zfinx.stderr
new file mode 100644
index 0000000000000..af0e53f34f23a
--- /dev/null
+++ b/tests/ui/target-feature/forbidden-hardfloat-target-feature-attribute-f-zfinx.stderr
@@ -0,0 +1,8 @@
+error: target feature `zfinx` cannot be enabled with `#[target_feature]`: this feature is incompatible with the target ABI
+  --> $DIR/forbidden-hardfloat-target-feature-attribute-f-zfinx.rs:10:18
+   |
+LL | #[target_feature(enable = "zdinx")]
+   |                  ^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+