Check that target features required by LLVM intrinsics are enabled

src/tools/miri/src/helpers.rs

@@ -1063,6 +1063,24 @@ fn get_twice_wide_int_ty(&self, ty: Ty<'tcx>) -> Ty<'tcx> {
             _ => span_bug!(this.cur_span(), "unexpected type: {ty:?}"),
         }
     }
+
+    /// Checks that target feature `target_feature` is enabled.
+    ///
+    /// If not enabled, emits an UB error that states that the feature is
+    /// required by `intrinsic`.
+    fn expect_target_feature_for_intrinsic(
+        &self,
+        intrinsic: Symbol,
+        target_feature: &str,
+    ) -> InterpResult<'tcx, ()> {
+        let this = self.eval_context_ref();
+        if !this.tcx.sess.unstable_target_features.contains(&Symbol::intern(target_feature)) {
+            throw_ub_format!(
+                "attempted to call intrinsic `{intrinsic}` that requires missing target feature {target_feature}"
+            );
+        }
+        Ok(())
+    }
 }
 
 impl<'mir, 'tcx> MiriMachine<'mir, 'tcx> {

src/tools/miri/src/shims/foreign_items.rs

@@ -1008,9 +1008,11 @@ fn emulate_foreign_item_inner(
             "llvm.arm.hint" if this.tcx.sess.target.arch == "arm" => {
                 let [arg] = this.check_shim(abi, Abi::Unadjusted, link_name, args)?;
                 let arg = this.read_scalar(arg)?.to_i32()?;
+                // Note that different arguments might have different target feature requirements.
                 match arg {
                     // YIELD
                     1 => {
+                        this.expect_target_feature_for_intrinsic(link_name, "v6")?;
                         this.yield_active_thread();
                     }
                     _ => {

src/tools/miri/src/shims/x86/aesni.rs

@@ -18,6 +18,7 @@ fn emulate_x86_aesni_intrinsic(
         dest: &PlaceTy<'tcx, Provenance>,
     ) -> InterpResult<'tcx, EmulateForeignItemResult> {
         let this = self.eval_context_mut();
+        this.expect_target_feature_for_intrinsic(link_name, "aes")?;
         // Prefix should have already been checked.
         let unprefixed_name = link_name.as_str().strip_prefix("llvm.x86.aesni.").unwrap();
 

src/tools/miri/src/shims/x86/mod.rs

@@ -164,7 +164,11 @@ enum FloatBinOp {
 impl FloatBinOp {
     /// Convert from the `imm` argument used to specify the comparison
     /// operation in intrinsics such as `llvm.x86.sse.cmp.ss`.
-    fn cmp_from_imm(imm: i8, intrinsic: &str) -> InterpResult<'_, Self> {
+    fn cmp_from_imm<'tcx>(
+        this: &crate::MiriInterpCx<'_, 'tcx>,
+        imm: i8,
+        intrinsic: Symbol,
+    ) -> InterpResult<'tcx, Self> {
         // Only bits 0..=4 are used, remaining should be zero.
         if imm & !0b1_1111 != 0 {
             throw_unsup_format!("invalid `imm` parameter of {intrinsic}: 0x{imm:x}");
@@ -174,7 +178,7 @@ fn cmp_from_imm(imm: i8, intrinsic: &str) -> InterpResult<'_, Self> {
         // Bits 0..=2 specifies the operation.
         // `gt` indicates the result to be returned when the LHS is strictly
         // greater than the RHS, and so on.
-        let (gt, lt, eq, unord) = match imm & 0b111 {
+        let (gt, lt, eq, mut unord) = match imm & 0b111 {
             // Equal
             0x0 => (false, false, true, false),
             // Less-than
@@ -194,7 +198,10 @@ fn cmp_from_imm(imm: i8, intrinsic: &str) -> InterpResult<'_, Self> {
             _ => unreachable!(),
         };
         // When bit 3 is 1 (only possible in AVX), unord is toggled.
-        let unord = unord ^ (imm & 0b1000 != 0);
+        if imm & 0b1000 != 0 {
+            this.expect_target_feature_for_intrinsic(intrinsic, "avx")?;
+            unord = !unord;
+        }
         Ok(Self::Cmp { gt, lt, eq, unord })
     }
 }

src/tools/miri/src/shims/x86/sse.rs

@@ -21,6 +21,7 @@ fn emulate_x86_sse_intrinsic(
         dest: &PlaceTy<'tcx, Provenance>,
     ) -> InterpResult<'tcx, EmulateForeignItemResult> {
         let this = self.eval_context_mut();
+        this.expect_target_feature_for_intrinsic(link_name, "sse")?;
         // Prefix should have already been checked.
         let unprefixed_name = link_name.as_str().strip_prefix("llvm.x86.sse.").unwrap();
         // All these intrinsics operate on 128-bit (f32x4) SIMD vectors unless stated otherwise.
@@ -107,10 +108,8 @@ fn emulate_x86_sse_intrinsic(
                 let [left, right, imm] =
                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
 
-                let which = FloatBinOp::cmp_from_imm(
-                    this.read_scalar(imm)?.to_i8()?,
-                    "llvm.x86.sse.cmp.ss",
-                )?;
+                let which =
+                    FloatBinOp::cmp_from_imm(this, this.read_scalar(imm)?.to_i8()?, link_name)?;
 
                 bin_op_simd_float_first::<Single>(this, which, left, right, dest)?;
             }
@@ -126,10 +125,8 @@ fn emulate_x86_sse_intrinsic(
                 let [left, right, imm] =
                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
 
-                let which = FloatBinOp::cmp_from_imm(
-                    this.read_scalar(imm)?.to_i8()?,
-                    "llvm.x86.sse.cmp.ps",
-                )?;
+                let which =
+                    FloatBinOp::cmp_from_imm(this, this.read_scalar(imm)?.to_i8()?, link_name)?;
 
                 bin_op_simd_float_all::<Single>(this, which, left, right, dest)?;
             }

src/tools/miri/src/shims/x86/sse2.rs

@@ -20,6 +20,7 @@ fn emulate_x86_sse2_intrinsic(
         dest: &PlaceTy<'tcx, Provenance>,
     ) -> InterpResult<'tcx, EmulateForeignItemResult> {
         let this = self.eval_context_mut();
+        this.expect_target_feature_for_intrinsic(link_name, "sse2")?;
         // Prefix should have already been checked.
         let unprefixed_name = link_name.as_str().strip_prefix("llvm.x86.sse2.").unwrap();
 
@@ -473,10 +474,8 @@ enum ShiftOp {
                 let [left, right, imm] =
                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
 
-                let which = FloatBinOp::cmp_from_imm(
-                    this.read_scalar(imm)?.to_i8()?,
-                    "llvm.x86.sse2.cmp.sd",
-                )?;
+                let which =
+                    FloatBinOp::cmp_from_imm(this, this.read_scalar(imm)?.to_i8()?, link_name)?;
 
                 bin_op_simd_float_first::<Double>(this, which, left, right, dest)?;
             }
@@ -492,10 +491,8 @@ enum ShiftOp {
                 let [left, right, imm] =
                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
 
-                let which = FloatBinOp::cmp_from_imm(
-                    this.read_scalar(imm)?.to_i8()?,
-                    "llvm.x86.sse2.cmp.pd",
-                )?;
+                let which =
+                    FloatBinOp::cmp_from_imm(this, this.read_scalar(imm)?.to_i8()?, link_name)?;
 
                 bin_op_simd_float_all::<Double>(this, which, left, right, dest)?;
             }

src/tools/miri/src/shims/x86/sse3.rs

@@ -18,6 +18,7 @@ fn emulate_x86_sse3_intrinsic(
         dest: &PlaceTy<'tcx, Provenance>,
     ) -> InterpResult<'tcx, EmulateForeignItemResult> {
         let this = self.eval_context_mut();
+        this.expect_target_feature_for_intrinsic(link_name, "sse3")?;
         // Prefix should have already been checked.
         let unprefixed_name = link_name.as_str().strip_prefix("llvm.x86.sse3.").unwrap();
 

src/tools/miri/src/shims/x86/sse41.rs

@@ -18,6 +18,7 @@ fn emulate_x86_sse41_intrinsic(
         dest: &PlaceTy<'tcx, Provenance>,
     ) -> InterpResult<'tcx, EmulateForeignItemResult> {
         let this = self.eval_context_mut();
+        this.expect_target_feature_for_intrinsic(link_name, "sse4.1")?;
         // Prefix should have already been checked.
         let unprefixed_name = link_name.as_str().strip_prefix("llvm.x86.sse41.").unwrap();
 

src/tools/miri/src/shims/x86/ssse3.rs

@@ -18,6 +18,7 @@ fn emulate_x86_ssse3_intrinsic(
         dest: &PlaceTy<'tcx, Provenance>,
     ) -> InterpResult<'tcx, EmulateForeignItemResult> {
         let this = self.eval_context_mut();
+        this.expect_target_feature_for_intrinsic(link_name, "ssse3")?;
         // Prefix should have already been checked.
         let unprefixed_name = link_name.as_str().strip_prefix("llvm.x86.ssse3.").unwrap();
 

src/tools/miri/tests/fail/shims/intrinsic_target_feature.rs

@@ -0,0 +1,42 @@
+// Ignore everything except x86 and x86_64
+// Any new targets that are added to CI should be ignored here.
+// We cannot use `cfg`-based tricks here since the output would be
+// different for non-x86 targets.
+//@ignore-target-aarch64
+//@ignore-target-arm
+//@ignore-target-avr
+//@ignore-target-s390x
+//@ignore-target-thumbv7em
+//@ignore-target-wasm32
+// Explicitly disable SSE4.1 because it is enabled by default on macOS
+//@compile-flags: -C target-feature=-sse4.1
+
+#![feature(link_llvm_intrinsics, simd_ffi)]
+
+#[cfg(target_arch = "x86")]
+use std::arch::x86::*;
+#[cfg(target_arch = "x86_64")]
+use std::arch::x86_64::*;
+
+fn main() {
+    assert!(is_x86_feature_detected!("sse"));
+    assert!(!is_x86_feature_detected!("sse4.1"));
+
+    unsafe {
+        // Pass, since SSE is enabled
+        addss(_mm_setzero_ps(), _mm_setzero_ps());
+
+        // Fail, since SSE4.1 is not enabled
+        dpps(_mm_setzero_ps(), _mm_setzero_ps(), 0);
+        //~^ ERROR: Undefined Behavior: attempted to call intrinsic `llvm.x86.sse41.dpps` that requires missing target feature sse4.1
+    }
+}
+
+#[allow(improper_ctypes)]
+extern "C" {
+    #[link_name = "llvm.x86.sse.add.ss"]
+    fn addss(a: __m128, b: __m128) -> __m128;
+
+    #[link_name = "llvm.x86.sse41.dpps"]
+    fn dpps(a: __m128, b: __m128, imm8: u8) -> __m128;
+}

src/tools/miri/tests/fail/shims/intrinsic_target_feature.stderr

@@ -0,0 +1,15 @@
+error: Undefined Behavior: attempted to call intrinsic `llvm.x86.sse41.dpps` that requires missing target feature sse4.1
+  --> $DIR/intrinsic_target_feature.rs:LL:CC
+   |
+LL |         dpps(_mm_setzero_ps(), _mm_setzero_ps(), 0);
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ attempted to call intrinsic `llvm.x86.sse41.dpps` that requires missing target feature sse4.1
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+   = note: BACKTRACE:
+   = note: inside `main` at $DIR/intrinsic_target_feature.rs:LL:CC
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to previous error
+