rustc_target: Stop using "string typing" for TLS models

Introduce `enum TlsModel` instead.

5 files changed, 61 insertions, 11 deletions

diff --git a/src/librustc_target/spec/cloudabi_base.rs b/src/librustc_target/spec/cloudabi_base.rs
index 53af9dcc186..3659c9ecdfc 100644
--- a/src/librustc_target/spec/cloudabi_base.rs
+++ b/src/librustc_target/spec/cloudabi_base.rs
@@ -1,4 +1,4 @@
-use crate::spec::{LinkArgs, LinkerFlavor, RelroLevel, TargetOptions};
+use crate::spec::{LinkArgs, LinkerFlavor, RelroLevel, TargetOptions, TlsModel};
 
 pub fn opts() -> TargetOptions {
     let mut args = LinkArgs::new();
@@ -29,7 +29,7 @@ pub fn opts() -> TargetOptions {
         // (Global Offset Table) to obtain the effective address of a
         // thread-local variable. Using a GOT is useful only when doing
         // dynamic linking.
-        tls_model: "local-exec".to_string(),
+        tls_model: TlsModel::LocalExec,
         relro_level: RelroLevel::Full,
         ..Default::default()
     }
diff --git a/src/librustc_target/spec/hermit_base.rs b/src/librustc_target/spec/hermit_base.rs
index cb12055290e..18fb2aa3d56 100644
--- a/src/librustc_target/spec/hermit_base.rs
+++ b/src/librustc_target/spec/hermit_base.rs
@@ -1,4 +1,5 @@
-use crate::spec::{LinkArgs, LinkerFlavor, LldFlavor, PanicStrategy, RelocModel, TargetOptions};
+use crate::spec::{LinkArgs, LinkerFlavor, LldFlavor, PanicStrategy};
+use crate::spec::{RelocModel, TargetOptions, TlsModel};
 
 pub fn opts() -> TargetOptions {
     let mut pre_link_args = LinkArgs::new();
@@ -17,7 +18,7 @@ pub fn opts() -> TargetOptions {
         position_independent_executables: true,
         relocation_model: RelocModel::Static,
         target_family: None,
-        tls_model: "initial-exec".to_string(),
+        tls_model: TlsModel::InitialExec,
         ..Default::default()
     }
 }
diff --git a/src/librustc_target/spec/hermit_kernel_base.rs b/src/librustc_target/spec/hermit_kernel_base.rs
index 11599fda409..7f2dada714d 100644
--- a/src/librustc_target/spec/hermit_kernel_base.rs
+++ b/src/librustc_target/spec/hermit_kernel_base.rs
@@ -1,4 +1,5 @@
-use crate::spec::{LinkArgs, LinkerFlavor, LldFlavor, PanicStrategy, RelocModel, TargetOptions};
+use crate::spec::{LinkArgs, LinkerFlavor, LldFlavor, PanicStrategy};
+use crate::spec::{RelocModel, TargetOptions, TlsModel};
 
 pub fn opts() -> TargetOptions {
     let mut pre_link_args = LinkArgs::new();
@@ -18,7 +19,7 @@ pub fn opts() -> TargetOptions {
         position_independent_executables: true,
         relocation_model: RelocModel::Static,
         target_family: None,
-        tls_model: "initial-exec".to_string(),
+        tls_model: TlsModel::InitialExec,
         ..Default::default()
     }
 }
diff --git a/src/librustc_target/spec/mod.rs b/src/librustc_target/spec/mod.rs
index 77fc78e8148..e853c07632f 100644
--- a/src/librustc_target/spec/mod.rs
+++ b/src/librustc_target/spec/mod.rs
@@ -305,6 +305,42 @@ impl ToJson for RelocModel {
     }
 }
 
+#[derive(Clone, Copy, PartialEq, Hash, Debug)]
+pub enum TlsModel {
+    GeneralDynamic,
+    LocalDynamic,
+    InitialExec,
+    LocalExec,
+}
+
+impl FromStr for TlsModel {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<TlsModel, ()> {
+        Ok(match s {
+            // Note the difference "general" vs "global" difference. The model name is "general",
+            // but the user-facing option name is "global" for consistency with other compilers.
+            "global-dynamic" => TlsModel::GeneralDynamic,
+            "local-dynamic" => TlsModel::LocalDynamic,
+            "initial-exec" => TlsModel::InitialExec,
+            "local-exec" => TlsModel::LocalExec,
+            _ => return Err(()),
+        })
+    }
+}
+
+impl ToJson for TlsModel {
+    fn to_json(&self) -> Json {
+        match *self {
+            TlsModel::GeneralDynamic => "global-dynamic",
+            TlsModel::LocalDynamic => "local-dynamic",
+            TlsModel::InitialExec => "initial-exec",
+            TlsModel::LocalExec => "local-exec",
+        }
+        .to_json()
+    }
+}
+
 pub enum LoadTargetError {
     BuiltinTargetNotFound(String),
     Other(String),
@@ -660,7 +696,7 @@ pub struct TargetOptions {
     pub code_model: Option<String>,
     /// TLS model to use. Options are "global-dynamic" (default), "local-dynamic", "initial-exec"
     /// and "local-exec". This is similar to the -ftls-model option in GCC/Clang.
-    pub tls_model: String,
+    pub tls_model: TlsModel,
     /// Do not emit code that uses the "red zone", if the ABI has one. Defaults to false.
     pub disable_redzone: bool,
     /// Eliminate frame pointers from stack frames if possible. Defaults to true.
@@ -863,7 +899,7 @@ impl Default for TargetOptions {
             executables: false,
             relocation_model: RelocModel::Pic,
             code_model: None,
-            tls_model: "global-dynamic".to_string(),
+            tls_model: TlsModel::GeneralDynamic,
             disable_redzone: false,
             eliminate_frame_pointer: true,
             function_sections: true,
@@ -1060,6 +1096,18 @@ impl Target {
                     Some(Ok(()))
                 })).unwrap_or(Ok(()))
             } );
+            ($key_name:ident, TlsModel) => ( {
+                let name = (stringify!($key_name)).replace("_", "-");
+                obj.find(&name[..]).and_then(|o| o.as_string().and_then(|s| {
+                    match s.parse::<TlsModel>() {
+                        Ok(tls_model) => base.options.$key_name = tls_model,
+                        _ => return Some(Err(format!("'{}' is not a valid TLS model. \
+                                                      Run `rustc --print tls-models` to \
+                                                      see the list of supported values.", s))),
+                    }
+                    Some(Ok(()))
+                })).unwrap_or(Ok(()))
+            } );
             ($key_name:ident, PanicStrategy) => ( {
                 let name = (stringify!($key_name)).replace("_", "-");
                 obj.find(&name[..]).and_then(|o| o.as_string().and_then(|s| {
@@ -1200,7 +1248,7 @@ impl Target {
         key!(executables, bool);
         key!(relocation_model, RelocModel)?;
         key!(code_model, optional);
-        key!(tls_model);
+        key!(tls_model, TlsModel)?;
         key!(disable_redzone, bool);
         key!(eliminate_frame_pointer, bool);
         key!(function_sections, bool);
diff --git a/src/librustc_target/spec/wasm32_base.rs b/src/librustc_target/spec/wasm32_base.rs
index 08bade2abf4..bb19b9d00e8 100644
--- a/src/librustc_target/spec/wasm32_base.rs
+++ b/src/librustc_target/spec/wasm32_base.rs
@@ -1,4 +1,4 @@
-use super::{LinkerFlavor, LldFlavor, PanicStrategy, RelocModel, TargetOptions};
+use super::{LinkerFlavor, LldFlavor, PanicStrategy, RelocModel, TargetOptions, TlsModel};
 use std::collections::BTreeMap;
 
 pub fn options() -> TargetOptions {
@@ -138,7 +138,7 @@ pub fn options() -> TargetOptions {
         // `has_elf_tls`) and we need to get it to work by specifying
         // `local-exec` as that's all that's implemented in LLVM today for wasm.
         has_elf_tls: true,
-        tls_model: "local-exec".to_string(),
+        tls_model: TlsModel::LocalExec,
 
         // gdb scripts don't work on wasm blobs
         emit_debug_gdb_scripts: false,