Update xarch to track more instruction metadata as flags (#83473)

* Reorder entries in instrsxarch to make finding SIMD instructions easier

* Remove unused instructions: cvtpd2pi, cvtpi2pd, cvtpi2ps, cvtps2pi, cvttpd2pi, and cvttps2pi

* Updating the xarch SIMD instructions to track flags indicating REX.W bit encoding and VEX/EVEX support

* Update the emitter to take advantage of the new insFlags

* Ensure TakesRexWPrefix works on x86

* Properly track REX.W encoding for VEX vs EVEX

* Ensure supportsVEX is set before supportsEVEX

* Ensure canUseVexEncoding is true when ForceEVEXEncoding is set

* Track how some special EVEX instructions are handled differently

* Apply formatting patch

* Ensure REX.WX is handled for EVEX where required

src/coreclr/jit/compiler.cpp

@@ -2348,18 +2348,18 @@ void Compiler::compSetProcessor()
 #ifdef TARGET_XARCH
     if (!compIsForInlining())
     {
-        if (canUseEvexEncoding())
-        {
-            codeGen->GetEmitter()->SetUseEvexEncoding(true);
-            // TODO-XArch-AVX512 : Revisit other flags to be set once avx512 instructions are added.
-        }
         if (canUseVexEncoding())
         {
             codeGen->GetEmitter()->SetUseVEXEncoding(true);
             // Assume each JITted method does not contain AVX instruction at first
             codeGen->GetEmitter()->SetContainsAVX(false);
             codeGen->GetEmitter()->SetContains256bitOrMoreAVX(false);
         }
+        if (canUseEvexEncoding())
+        {
+            codeGen->GetEmitter()->SetUseEvexEncoding(true);
+            // TODO-XArch-AVX512 : Revisit other flags to be set once avx512 instructions are added.
+        }
     }
 #endif // TARGET_XARCH
 }

src/coreclr/jit/compiler.h

@@ -9197,6 +9197,13 @@ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 #ifdef TARGET_XARCH
     bool canUseVexEncoding() const
     {
+#ifdef DEBUG
+        if (JitConfig.JitForceEVEXEncoding())
+        {
+            return true;
+        }
+#endif // DEBUG
+
         return compOpportunisticallyDependsOn(InstructionSet_AVX);
     }
 

src/coreclr/jit/emit.h

@@ -1109,7 +1109,7 @@ class emitter
         }
 #endif // TARGET_LOONGARCH64
 
-        emitAttr idOpSize()
+        emitAttr idOpSize() const
         {
             return emitDecodeSize(_idOpSize);
         }