Avoid enabling AVX when rustc isn't using it

This is needed for ABI to match

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "cloudflare-zlib-sys"
-version = "0.3.4"
+version = "0.3.5"
 edition = "2021"
 authors = ["Vlad Krasnov <[email protected]>", "Kornel Lesiński <[email protected]>", "Mark Adler <[email protected]>"]
 categories = ["external-ffi-bindings", "compression"]

rust/build.rs

@@ -4,15 +4,25 @@ use std::path::PathBuf;
 fn main() {
     let mut cc = cc::Build::new();
     let comp = cc.get_compiler();
-    let msvc_bugs = comp.is_like_msvc();
+    let is_msvc = comp.is_like_msvc();
     cc.warnings(false);
     cc.pic(true);
 
-    let target_pointer_width = env::var("CARGO_CFG_TARGET_POINTER_WIDTH").expect("CARGO_CFG_TARGET_POINTER_WIDTH var");
-    let target_arch = env::var("CARGO_CFG_TARGET_ARCH").expect("CARGO_CFG_TARGET_ARCH var");
+    let target_pointer_width = env::var("CARGO_CFG_TARGET_POINTER_WIDTH").expect("CARGO_CFG_TARGET_POINTER_WIDTH");
+    let target_endian = env::var("CARGO_CFG_TARGET_ENDIAN").expect("CARGO_CFG_TARGET_ENDIAN");
+    let target_arch = env::var("CARGO_CFG_TARGET_ARCH").expect("CARGO_CFG_TARGET_ARCH");
+    let target_feature = env::var("CARGO_CFG_TARGET_FEATURE").unwrap_or_default();
+    let has_feature = |f| target_feature.split(',').any(|t| t == f);
+
+    if target_endian != "little" {
+        println!("cargo::error=cloudflare-zlib does not support big endian");
+        // don't exit(1): https://github.com/rust-lang/cargo/issues/15038
+    }
 
     if target_pointer_width != "64" {
         println!("cargo:warning=cloudflare-zlib does not support 32-bit architectures");
+        println!("cargo::error=cloudflare-zlib does not support 32-bit architectures");
+        // don't exit(1): https://github.com/rust-lang/cargo/issues/15038
     }
 
     if let Ok(target_cpu) = env::var("TARGET_CPU") {
@@ -26,19 +36,61 @@ fn main() {
     if target_arch == "aarch64" {
         cc.define("INFLATE_CHUNK_SIMD_NEON", Some("1"));
         cc.define("ADLER32_SIMD_NEON", Some("1"));
+        cc.flag_if_supported(if is_msvc { "/arch:armv8.3" } else { "-march=armv8-a+crc" });
     } else if target_arch == "x86_64" {
-        cc.define("INFLATE_CHUNK_SIMD_SSE2", Some("1"));
-        if msvc_bugs {
-            cc.define("__x86_64__", Some("1"));
+        let sse42_flag = if is_msvc { "/arch:SSE4.2" } else { "-msse4.2" };
+
+        let has_avx = has_feature("avx"); // AVX changes ABI, so it can't be enabled just in C
+        let has_sse42 = has_avx || has_feature("sse4.2") ||
+            cc.is_flag_supported(sse42_flag).unwrap_or(false) ||
+            // MSDN says /arch:SSE4.2 exists, but MSVC disagrees.
+            (is_msvc && cc.is_flag_supported("/arch:AVX").unwrap_or(false));
+        let has_ssse3 = has_avx || has_feature("ssse3") || cc.is_flag_supported("-mssse3").unwrap_or(false);
+        let has_pcmul = has_feature("pclmulqdq") || cc.is_flag_supported("-mpclmul").unwrap_or(false);
+
+        if has_avx {
+            cc.define("HAS_AVX", Some("1"));
+            cc.flag(if is_msvc { "/arch:AVX" } else { "-mavx" });
+        } else if has_sse42 {
+            cc.flag(sse42_flag);
+        }
+
+        if has_sse42 {
+            cc.define("INFLATE_CHUNK_SIMD_SSE2", Some("1"));
+            if is_msvc {
+                cc.define("__x86_64__", Some("1"));
+            }
+            cc.define("HAS_SSE2", Some("1"));
+            cc.define("HAS_SSE42", Some("1"));
+
+            if has_ssse3 {
+                cc.flag_if_supported("-mssse3");
+                cc.define("HAS_SSSE3", Some("1"));
+                cc.define("ADLER32_SIMD_SSSE3", Some("1"));
+            }
+
+            if has_pcmul {
+                cc.flag_if_supported("-mpclmul");
+                cc.define("HAS_PCLMUL", Some("1"));
+                cc.file(vendor.join("crc32_simd.c"));
+
+                if has_feature("pclmulqdq") {
+                    cc.define("SKIP_CPUID_CHECK", Some("1"));
+                }
+            }
+
+        } else {
+            println!("cargo::error=This build has disabled SSE4.2 support, but cloudflare-zlib-sys requires it");
+            println!("cargo:warning=Build with RUSTFLAGS='-Ctarget-feature=+sse4.2. Currently enabled: {target_feature}");
+            cc.define("INFLATE_CHUNK_GENERIC", Some("1"));
         }
     }
 
     cc.define("INFLATE_CHUNK_READ_64LE", Some("1"));
 
-    if msvc_bugs {
+    if is_msvc {
         cc.define("_CRT_SECURE_NO_DEPRECATE", Some("1"));
         cc.define("_CRT_NONSTDC_NO_DEPRECATE", Some("1"));
-        cc.flag_if_supported("/arch:AVX");
     } else {
         cc.define("HAVE_UNISTD_H", Some("1"));
         cc.define("HAVE_HIDDEN", Some("1"));
@@ -47,20 +99,6 @@ fn main() {
             cc.define("HAVE_OFF64_T", Some("1"));
             cc.define("_LARGEFILE64_SOURCE", Some("1"));
         }
-        if target_arch == "aarch64" {
-            cc.flag_if_supported("-march=armv8-a+crc");
-        } else {
-            if cc.is_flag_supported("-mssse3").is_ok() {
-                cc.flag("-mssse3");
-                cc.define("ADLER32_SIMD_SSSE3", Some("1"));
-            }
-            if cc.is_flag_supported("-mpclmul").is_ok() {
-                cc.flag("-mpclmul");
-                cc.define("HAS_PCLMUL", None);
-                cc.file(vendor.join("crc32_simd.c"));
-                cc.flag_if_supported("-msse4.2");
-            }
-        }
     }
 
     cc.file(vendor.join("adler32.c"));