Auto merge of #102503 - cuviper:x86-stack-probes, r=nagisa

Enable inline stack probes on X86 with LLVM 16

The known problems with x86 inline-asm stack probes have been solved on LLVM main (16), so this flips the switch. Anyone using bleeding-edge LLVM with rustc can start testing this, as I have done locally. We'll get more direct rust-ci when LLVM 16 branches and we start our upgrade, and we can always patch or disable it then if we find new problems.

The previous attempt was #77885, reverted in #84708.

src/test/assembly/x86-stack-probes.rs

@@ -0,0 +1,42 @@
+// min-llvm-version: 16
+// revisions: x86_64 i686
+// assembly-output: emit-asm
+//[x86_64] compile-flags: --target x86_64-unknown-linux-gnu
+//[x86_64] needs-llvm-components: x86
+//[i686] compile-flags: --target i686-unknown-linux-gnu
+//[i686] needs-llvm-components: x86
+// compile-flags: -C llvm-args=-x86-asm-syntax=intel
+
+#![feature(no_core, lang_items)]
+#![crate_type = "lib"]
+#![no_core]
+
+#[lang = "sized"]
+trait Sized {}
+#[lang = "copy"]
+trait Copy {}
+
+impl Copy for u8 {}
+
+// Check that inline-asm stack probes are generated correctly.
+// To avoid making this test fragile to slight asm changes,
+// we only check that the stack pointer is decremented by a page at a time,
+// instead of matching the whole probe sequence.
+
+// CHECK-LABEL: small_stack_probe:
+#[no_mangle]
+pub fn small_stack_probe(x: u8, f: fn(&mut [u8; 8192])) {
+    // CHECK-NOT: __rust_probestack
+    // x86_64: sub rsp, 4096
+    // i686: sub esp, 4096
+    f(&mut [x; 8192]);
+}
+
+// CHECK-LABEL: big_stack_probe:
+#[no_mangle]
+pub fn big_stack_probe(x: u8, f: fn(&[u8; 65536])) {
+    // CHECK-NOT: __rust_probestack
+    // x86_64: sub rsp, 4096
+    // i686: sub esp, 4096
+    f(&mut [x; 65536]);
+}

src/test/codegen/stack-probes-call.rs

@@ -5,8 +5,10 @@
 // revisions: i686 x86_64
 //[i686] compile-flags: --target i686-unknown-linux-gnu
 //[i686] needs-llvm-components: x86
+//[i686] ignore-llvm-version: 16 - 99
 //[x86_64] compile-flags: --target x86_64-unknown-linux-gnu
 //[x86_64] needs-llvm-components: x86
+//[x86_64] ignore-llvm-version: 16 - 99
 
 #![crate_type = "rlib"]
 #![feature(no_core, lang_items)]

src/test/codegen/stack-probes-inline.rs

@@ -2,7 +2,7 @@
 // or `StackProbeType::InlineOrCall` when running on newer LLVM.
 
 // compile-flags: -C no-prepopulate-passes
-// revisions: powerpc powerpc64 powerpc64le s390x
+// revisions: powerpc powerpc64 powerpc64le s390x i686 x86_64
 //[powerpc] compile-flags: --target powerpc-unknown-linux-gnu
 //[powerpc] needs-llvm-components: powerpc
 //[powerpc64] compile-flags: --target powerpc64-unknown-linux-gnu
@@ -11,6 +11,12 @@
 //[powerpc64le] needs-llvm-components: powerpc
 //[s390x] compile-flags: --target s390x-unknown-linux-gnu
 //[s390x] needs-llvm-components: systemz
+//[i686] compile-flags: --target i686-unknown-linux-gnu
+//[i686] needs-llvm-components: x86
+//[i686] min-llvm-version: 16
+//[x86_64] compile-flags: --target x86_64-unknown-linux-gnu
+//[x86_64] needs-llvm-components: x86
+//[x86_64] min-llvm-version: 16
 
 #![crate_type = "rlib"]
 #![feature(no_core, lang_items)]