trycopy: reimplement sparse_mmap's trycopy with inline asm

Cargo.lock

@@ -2741,6 +2741,7 @@ dependencies = [
  "pal_event",
  "sparse_mmap",
  "thiserror 2.0.16",
+ "trycopy",
  "zerocopy 0.8.25",
 ]
 
@@ -6877,13 +6878,12 @@ dependencies = [
 name = "sparse_mmap"
 version = "0.0.0"
 dependencies = [
- "cc",
- "criterion",
  "getrandom 0.3.3",
  "libc",
  "pal",
  "parking_lot",
  "thiserror 2.0.16",
+ "trycopy",
  "windows-sys 0.61.0",
  "zerocopy 0.8.25",
 ]
@@ -7675,6 +7675,16 @@ version = "0.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e421abadd41a4225275504ea4d6566923418b7f05506fbc9c0fe86ba7396114b"
 
+[[package]]
+name = "trycopy"
+version = "0.0.0"
+dependencies = [
+ "criterion",
+ "libc",
+ "thiserror 2.0.16",
+ "windows-sys 0.61.0",
+]
+
 [[package]]
 name = "typed-path"
 version = "0.11.0"
@@ -8234,8 +8244,8 @@ dependencies = [
  "parking_lot",
  "pci_core",
  "safeatomic",
- "sparse_mmap",
  "tracing",
+ "trycopy",
  "uevent",
  "vfio-bindings",
  "vfio_sys",

Cargo.toml

@@ -153,6 +153,7 @@ test_with_tracing = { path = "support/test_with_tracing" }
 test_with_tracing_macro = { path = "support/test_with_tracing/test_with_tracing_macro" }
 tracelimit = { path = "support/tracelimit" }
 tracing_helpers = { path = "support/tracing_helpers" }
+trycopy = { path = "support/trycopy" }
 ucs2 = { path = "support/ucs2" }
 uevent = { path = "support/uevent" }
 unix_socket = { path = "support/unix_socket" }
@@ -418,7 +419,6 @@ bitvec = { version = "1.1", default-features = false }
 blocking = "1.2"
 caps = "0.5"
 cargo_toml = "0.22"
-cc = "1.0"
 cfg-if = "1"
 clap = "4.2"
 crc32fast = { version = "1.3.2", default-features = false }

flowey/flowey_lib_hvlite/src/_jobs/check_clippy.rs

@@ -187,15 +187,6 @@ impl SimpleFlowNode for Node {
             }
         });
 
-        let extra_env = if matches!(
-            target.operating_system,
-            target_lexicon::OperatingSystem::Darwin(_)
-        ) {
-            Some(vec![("SPARSE_MMAP_NO_BUILD".into(), "1".into())])
-        } else {
-            None
-        };
-
         // HACK: the following behavior has been cargo-culted from our old
         // CI, and at some point, we should actually improve the testing
         // story on windows, so that we can run with FeatureSet::All in CI.
@@ -217,7 +208,7 @@ impl SimpleFlowNode for Node {
             profile: profile.clone(),
             features: features.clone(),
             target,
-            extra_env,
+            extra_env: None,
             exclude,
             keep_going: true,
             all_targets: true,

support/sparse_mmap/Cargo.toml

@@ -6,11 +6,9 @@ name = "sparse_mmap"
 edition.workspace = true
 rust-version.workspace = true
 
-[build-dependencies]
-cc.workspace = true
-
 [dependencies]
 pal.workspace = true
+trycopy.workspace = true
 
 thiserror.workspace = true
 zerocopy.workspace = true
@@ -31,12 +29,5 @@ windows-sys = { workspace = true, features = [
     "Win32_System_Threading",
 ]}
 
-[[bench]]
-name = "perf"
-harness = false
-
-[dev-dependencies]
-criterion.workspace = true
-
 [lints]
 workspace = true