From 6dfb6ccf8cac7d50d08bec08198686032d7e6630 Mon Sep 17 00:00:00 2001
From: merry <git@mary.rs>
Date: Sun, 14 Aug 2022 21:35:08 +0100
Subject: [PATCH] PreAllocator: Check if instruction supports a Vex prefix in
 IsVexSameOperandDestSrc1 (#3587)

---
 ARMeilleure/CodeGen/X86/AssemblerTable.cs | 5 +++++
 ARMeilleure/CodeGen/X86/PreAllocator.cs   | 6 +++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/ARMeilleure/CodeGen/X86/AssemblerTable.cs b/ARMeilleure/CodeGen/X86/AssemblerTable.cs
index 68791fbb79..3af4220419 100644
--- a/ARMeilleure/CodeGen/X86/AssemblerTable.cs
+++ b/ARMeilleure/CodeGen/X86/AssemblerTable.cs
@@ -4,6 +4,11 @@ namespace ARMeilleure.CodeGen.X86
 {
     partial class Assembler
     {
+        public static bool SupportsVexPrefix(X86Instruction inst)
+        {
+            return _instTable[(int)inst].Flags.HasFlag(InstructionFlags.Vex);
+        }
+
         private const int BadOp = 0;
 
         [Flags]
diff --git a/ARMeilleure/CodeGen/X86/PreAllocator.cs b/ARMeilleure/CodeGen/X86/PreAllocator.cs
index 72bf64edf2..7d2d4df0d0 100644
--- a/ARMeilleure/CodeGen/X86/PreAllocator.cs
+++ b/ARMeilleure/CodeGen/X86/PreAllocator.cs
@@ -1297,11 +1297,15 @@ namespace ARMeilleure.CodeGen.X86
         {
             if (IsIntrinsic(operation.Instruction))
             {
+                IntrinsicInfo info = IntrinsicTable.GetInfo(operation.Intrinsic);
+
+                bool hasVex = HardwareCapabilities.SupportsVexEncoding && Assembler.SupportsVexPrefix(info.Inst);
+
                 bool isUnary = operation.SourcesCount < 2;
 
                 bool hasVecDest = operation.Destination != default && operation.Destination.Type == OperandType.V128;
 
-                return !HardwareCapabilities.SupportsVexEncoding && !isUnary && hasVecDest;
+                return !hasVex && !isUnary && hasVecDest;
             }
 
             return false;