Rollup merge of #117141 - tmiasko:inline-target-features, r=oli-obk

Require target features to match exactly during inlining

In general it is not correct to inline a callee with a target features
that are subset of the callee. Require target features to match exactly
during inlining.

The exact match could be potentially relaxed, but this would require
identifying specific feature that are allowed to differ, those that need
to match, and those that can be present in caller but not in callee.

This resolves MIR part of #116573. For other concerns with respect to
the previous implementation also see areInlineCompatible in LLVM.

compiler/rustc_mir_transform/src/inline.rs

@@ -438,10 +438,8 @@ impl<'tcx> Inliner<'tcx> {
             return Err("incompatible instruction set");
         }
 
-        for feature in &callee_attrs.target_features {
-            if !self.codegen_fn_attrs.target_features.contains(feature) {
-                return Err("incompatible target feature");
-            }
+        if callee_attrs.target_features != self.codegen_fn_attrs.target_features {
+            return Err("incompatible target features");
         }
 
         Ok(())

tests/mir-opt/inline/inline_compatibility.rs

@@ -1,51 +1,71 @@
-// skip-filecheck
 // Checks that only functions with compatible attributes are inlined.
-//
 // only-x86_64
-// EMIT_MIR_FOR_EACH_PANIC_STRATEGY
+// compile-flags: -Cpanic=abort
 
 #![crate_type = "lib"]
 #![feature(no_sanitize)]
 #![feature(target_feature_11)]
 #![feature(c_variadic)]
 
-// EMIT_MIR inline_compatibility.inlined_target_feature.Inline.diff
+#[inline]
+#[target_feature(enable = "sse2")]
+unsafe fn sse2() {}
+
+#[inline]
+fn nop() {}
+
+// CHECK-LABEL: fn f0()
+// CHECK:       bb0: {
+// CHECK-NEXT:  return;
 #[target_feature(enable = "sse2")]
-pub unsafe fn inlined_target_feature() {
-    target_feature();
+pub unsafe fn f0() {
+    sse2();
 }
 
-// EMIT_MIR inline_compatibility.not_inlined_target_feature.Inline.diff
-pub unsafe fn not_inlined_target_feature() {
-    target_feature();
+// CHECK-LABEL: fn f1()
+// CHECK:       bb0: {
+// CHECK-NEXT:  sse2()
+pub unsafe fn f1() {
+    sse2();
 }
 
-// EMIT_MIR inline_compatibility.inlined_no_sanitize.Inline.diff
+// CHECK-LABEL: fn f2()
+// CHECK:       bb0: {
+// CHECK-NEXT:  nop()
+#[target_feature(enable = "avx")]
+pub unsafe fn f2() {
+    nop();
+}
+
+#[inline]
+#[no_sanitize(address)]
+pub unsafe fn no_sanitize() {}
+
+// CHECK-LABEL: fn inlined_no_sanitize()
+// CHECK:       bb0: {
+// CHECK-NEXT:  return;
 #[no_sanitize(address)]
 pub unsafe fn inlined_no_sanitize() {
     no_sanitize();
 }
 
-// EMIT_MIR inline_compatibility.not_inlined_no_sanitize.Inline.diff
+// CHECK-LABEL: fn not_inlined_no_sanitize()
+// CHECK:       bb0: {
+// CHECK-NEXT:  no_sanitize()
 pub unsafe fn not_inlined_no_sanitize() {
     no_sanitize();
 }
 
-#[inline]
-#[target_feature(enable = "sse2")]
-pub unsafe fn target_feature() {}
-
-#[inline]
-#[no_sanitize(address)]
-pub unsafe fn no_sanitize() {}
-
-// EMIT_MIR inline_compatibility.not_inlined_c_variadic.Inline.diff
+// CHECK-LABEL: fn not_inlined_c_variadic()
+// CHECK:       bb0: {
+// CHECK-NEXT:  StorageLive(_1)
+// CHECK-NEXT:  _1 = sum
 pub unsafe fn not_inlined_c_variadic() {
-    let s = sum(4u32, 4u32, 30u32, 200u32, 1000u32);
+    let _ = sum(4u32, 4u32, 30u32, 200u32, 1000u32);
 }
 
-#[no_mangle]
 #[inline(always)]
+#[no_mangle]
 unsafe extern "C" fn sum(n: u32, mut vs: ...) -> u32 {
     let mut s = 0;
     let mut i = 0;