XRay support flag in TargetOptions

Specify where XRay is supported. I only test ARM64 and x86_64, but hey
those others should work too, right? LLVM documentation says that MIPS
and PPC are also supported, but I don't have the hardware, so I won't
pretend. Naturally, more targets can be added later with more testing.

Author: ilammy

compiler/rustc_target/src/spec/aarch64_linux_android.rs

@@ -19,6 +19,7 @@ pub fn target() -> Target {
                 | SanitizerSet::MEMTAG
                 | SanitizerSet::SHADOWCALLSTACK
                 | SanitizerSet::ADDRESS,
+            supports_xray: true,
             ..super::android_base::opts()
         },
     }

compiler/rustc_target/src/spec/aarch64_unknown_linux_gnu.rs

@@ -17,6 +17,7 @@ pub fn target() -> Target {
                 | SanitizerSet::MEMTAG
                 | SanitizerSet::THREAD
                 | SanitizerSet::HWADDRESS,
+            supports_xray: true,
             ..super::linux_gnu_base::opts()
         },
     }

compiler/rustc_target/src/spec/aarch64_unknown_linux_musl.rs

@@ -3,6 +3,7 @@ use crate::spec::{Target, TargetOptions};
 pub fn target() -> Target {
     let mut base = super::linux_musl_base::opts();
     base.max_atomic_width = Some(128);
+    base.supports_xray = true;
 
     Target {
         llvm_target: "aarch64-unknown-linux-musl".into(),

compiler/rustc_target/src/spec/mod.rs

@@ -1718,6 +1718,9 @@ pub struct TargetOptions {
     /// The ABI of entry function.
     /// Default value is `Conv::C`, i.e. C call convention
     pub entry_abi: Conv,
+
+    /// Whether the target supports XRay instrumentation.
+    pub supports_xray: bool,
 }
 
 /// Add arguments for the given flavor and also for its "twin" flavors
@@ -1937,6 +1940,7 @@ impl Default for TargetOptions {
             supports_stack_protector: true,
             entry_name: "main".into(),
             entry_abi: Conv::C,
+            supports_xray: false,
         }
     }
 }
@@ -2592,6 +2596,7 @@ impl Target {
         key!(supports_stack_protector, bool);
         key!(entry_name);
         key!(entry_abi, Conv)?;
+        key!(supports_xray, bool);
 
         if base.is_builtin {
             // This can cause unfortunate ICEs later down the line.
@@ -2845,6 +2850,7 @@ impl ToJson for Target {
         target_option_val!(supports_stack_protector);
         target_option_val!(entry_name);
         target_option_val!(entry_abi);
+        target_option_val!(supports_xray);
 
         if let Some(abi) = self.default_adjusted_cabi {
             d.insert("default-adjusted-cabi".into(), Abi::name(abi).to_json());

compiler/rustc_target/src/spec/x86_64_linux_android.rs

@@ -8,6 +8,7 @@ pub fn target() -> Target {
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m64"]);
     base.stack_probes = StackProbeType::X86;
+    base.supports_xray = true;
 
     Target {
         llvm_target: "x86_64-linux-android".into(),

compiler/rustc_target/src/spec/x86_64_unknown_freebsd.rs

@@ -8,6 +8,7 @@ pub fn target() -> Target {
     base.stack_probes = StackProbeType::X86;
     base.supported_sanitizers =
         SanitizerSet::ADDRESS | SanitizerSet::CFI | SanitizerSet::MEMORY | SanitizerSet::THREAD;
+    base.supports_xray = true;
 
     Target {
         llvm_target: "x86_64-unknown-freebsd".into(),

compiler/rustc_target/src/spec/x86_64_unknown_linux_gnu.rs

@@ -12,6 +12,7 @@ pub fn target() -> Target {
         | SanitizerSet::LEAK
         | SanitizerSet::MEMORY
         | SanitizerSet::THREAD;
+    base.supports_xray = true;
 
     Target {
         llvm_target: "x86_64-unknown-linux-gnu".into(),

compiler/rustc_target/src/spec/x86_64_unknown_linux_musl.rs

@@ -12,6 +12,7 @@ pub fn target() -> Target {
         | SanitizerSet::LEAK
         | SanitizerSet::MEMORY
         | SanitizerSet::THREAD;
+    base.supports_xray = true;
 
     Target {
         llvm_target: "x86_64-unknown-linux-musl".into(),

compiler/rustc_target/src/spec/x86_64_unknown_netbsd.rs

@@ -11,6 +11,7 @@ pub fn target() -> Target {
         | SanitizerSet::LEAK
         | SanitizerSet::MEMORY
         | SanitizerSet::THREAD;
+    base.supports_xray = true;
 
     Target {
         llvm_target: "x86_64-unknown-netbsd".into(),

compiler/rustc_target/src/spec/x86_64_unknown_openbsd.rs

@@ -6,6 +6,7 @@ pub fn target() -> Target {
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m64"]);
     base.stack_probes = StackProbeType::X86;
+    base.supports_xray = true;
 
     Target {
         llvm_target: "x86_64-unknown-openbsd".into(),