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Restrict From<S> for {D,Subd}iagnosticMessage.

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Currently a `{D,Subd}iagnosticMessage` can be created from any type that
impls `Into<String>`. That includes `&str`, `String`, and `Cow<'static,
str>`, which are reasonable. It also includes `&String`, which is pretty
weird, and results in many places making unnecessary allocations for
patterns like this:
```
self.fatal(&format!(...))
```
This creates a string with `format!`, takes a reference, passes the
reference to `fatal`, which does an `into()`, which clones the
reference, doing a second allocation. Two allocations for a single
string, bleh.

This commit changes the `From` impls so that you can only create a
`{D,Subd}iagnosticMessage` from `&str`, `String`, or `Cow<'static,
str>`. This requires changing all the places that currently create one
from a `&String`. Most of these are of the `&format!(...)` form
described above; each one removes an unnecessary static `&`, plus an
allocation when executed. There are also a few places where the existing
use of `&String` was more reasonable; these now just use `clone()` at
the call site.

As well as making the code nicer and more efficient, this is a step
towards possibly using `Cow<'static, str>` in
`{D,Subd}iagnosticMessage::{Str,Eager}`. That would require changing
the `From<&'a str>` impls to `From<&'static str>`, which is doable, but
I'm not yet sure if it's worthwhile.
This commit is contained in:
Nicholas Nethercote
2023-04-20 13:26:58 +10:00
parent a368898de7
commit 6b62f37402
177 changed files with 791 additions and 787 deletions
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10
compiler/rustc_codegen_cranelift/src/lib.rs
View File

@@ -185,7 +185,7 @@ impl CodegenBackend for CraneliftCodegenBackend {
let mut config = self.config.borrow_mut();
if config.is_none() {
let new_config = BackendConfig::from_opts(&sess.opts.cg.llvm_args)
.unwrap_or_else(|err| sess.fatal(&err));
.unwrap_or_else(|err| sess.fatal(err));
*config = Some(new_config);
}
}
@@ -245,7 +245,7 @@ impl CodegenBackend for CraneliftCodegenBackend {
fn target_triple(sess: &Session) -> target_lexicon::Triple {
match sess.target.llvm_target.parse() {
Ok(triple) => triple,
Err(err) => sess.fatal(&format!("target not recognized: {}", err)),
Err(err) => sess.fatal(format!("target not recognized: {}", err)),
}
}
@@ -307,7 +307,7 @@ fn build_isa(sess: &Session, backend_config: &BackendConfig) -> Arc<dyn isa::Tar
Some(value) => {
let mut builder =
cranelift_codegen::isa::lookup(target_triple.clone()).unwrap_or_else(|err| {
sess.fatal(&format!("can't compile for {}: {}", target_triple, err));
sess.fatal(format!("can't compile for {}: {}", target_triple, err));
});
if let Err(_) = builder.enable(value) {
sess.fatal("the specified target cpu isn't currently supported by Cranelift.");
@@ -317,7 +317,7 @@ fn build_isa(sess: &Session, backend_config: &BackendConfig) -> Arc<dyn isa::Tar
None => {
let mut builder =
cranelift_codegen::isa::lookup(target_triple.clone()).unwrap_or_else(|err| {
sess.fatal(&format!("can't compile for {}: {}", target_triple, err));
sess.fatal(format!("can't compile for {}: {}", target_triple, err));
});
if target_triple.architecture == target_lexicon::Architecture::X86_64 {
// Don't use "haswell" as the default, as it implies `has_lzcnt`.
@@ -330,7 +330,7 @@ fn build_isa(sess: &Session, backend_config: &BackendConfig) -> Arc<dyn isa::Tar
match isa_builder.finish(flags) {
Ok(target_isa) => target_isa,
Err(err) => sess.fatal(&format!("failed to build TargetIsa: {}", err)),
Err(err) => sess.fatal(format!("failed to build TargetIsa: {}", err)),
}
}