Merge #2775

2775: Support SSE 4.2 for the Singlepass compiler r=ptitSeb a=batconjurer

Closes #2767 

# Description
This PR adds support for the SSE 4.2 instruction set in the singlepass compiler. Previously, only AVX was supported. This implementation may also work for SSE 4.1, but this should be double checked. It does use the `blendvps` instruction indroduced in SSE 4.1, so it cannot support any earlier SSE versions at present for sure. 

The following are the main changes:
 - The assembler has changed from a Vec<X64Relocation> to a struct containing this as well as the corresponding CPU feature (indicating AVX/SSE4.2/...)
 - A set of SSE function macros have been added. To handle non-destructive operations, additional moves may be made before executing the corresponding SSE instruction if `src1 != dst`
 - A minor change to the `EmitterX64` trait. It now has a function for returning a possible CPU feature.
 - The implementation of `EmitterX64` for the assembler has obviously changed. It chooses the emitted assembly based on the CPU feature.


Co-authored-by: R2D2 <jacob.turner870@gmail.com>
Co-authored-by: Jacob Turner <jacob.turner870@gmail.com>

lib/compiler-singlepass/Cargo.toml

@@ -32,6 +32,8 @@ target-lexicon = { version = "0.12.2", default-features = false }
 maintenance = { status = "actively-developed" }
 
 [features]
-default = ["std", "rayon"]
+default = ["std", "rayon", "avx"]
 std = ["wasmer-compiler/std", "wasmer-types/std"]
 core = ["hashbrown", "wasmer-types/core"]
+sse = []
+avx = []

lib/compiler-singlepass/src/compiler.rs

@@ -69,13 +69,16 @@ impl Compiler for SinglepassCompiler {
                 ))
             }
         }
-        if target.triple().architecture == Architecture::X86_64
-            && !target.cpu_features().contains(CpuFeature::AVX)
-        {
+
+        let simd_arch = if target.cpu_features().contains(CpuFeature::AVX) {
+            CpuFeature::AVX
+        } else if target.cpu_features().contains(CpuFeature::SSE42) {
+            CpuFeature::SSE42
+        } else {
             return Err(CompileError::UnsupportedTarget(
-                "x86_64 without AVX".to_string(),
+                "x86_64 without AVX or SSE 4.2".to_string(),
             ));
-        }
+        };
         if compile_info.features.multi_value {
             return Err(CompileError::UnsupportedFeature("multivalue".to_string()));
         }
@@ -131,7 +134,7 @@ impl Compiler for SinglepassCompiler {
 
                 match target.triple().architecture {
                     Architecture::X86_64 => {
-                        let machine = MachineX86_64::new();
+                        let machine = MachineX86_64::new(Some(simd_arch));
                         let mut generator = FuncGen::new(
                             module,
                             &self.config,