[RISC-V] Fix alignment for vector types (#99589)

For vector256 and vector512, set possible max alignment value.

Reference
https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-cc.adoc

src/coreclr/tools/Common/Compiler/VectorFieldLayoutAlgorithm.cs

@@ -52,12 +52,19 @@ public override ComputedInstanceFieldLayout ComputeInstanceLayout(DefType defTyp
                     // to the same alignment as __m128, which is supported by the ABI.
                     alignment = new LayoutInt(8);
                 }
-                else if (defType.Context.Target.Architecture == TargetArchitecture.ARM64 || defType.Context.Target.Architecture == TargetArchitecture.RiscV64)
+                else if (defType.Context.Target.Architecture == TargetArchitecture.ARM64)
                 {
                     // The Procedure Call Standard for ARM 64-bit (with SVE support) defaults to
                     // 16-byte alignment for __m256.
                     alignment = new LayoutInt(16);
                 }
+                else if (defType.Context.Target.Architecture == TargetArchitecture.RiscV64)
+                {
+                    // TODO-RISCV64: Update alignment to proper value when we implement RISC-V intrinsic.
+                    // RISC-V Vector Extenstion Intrinsic Document
+                    // https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/vector_type_infos.adoc
+                    alignment = new LayoutInt(16);
+                }
                 else
                 {
                     alignment = new LayoutInt(32);
@@ -73,12 +80,19 @@ public override ComputedInstanceFieldLayout ComputeInstanceLayout(DefType defTyp
                     // to the same alignment as __m128, which is supported by the ABI.
                     alignment = new LayoutInt(8);
                 }
-                else if (defType.Context.Target.Architecture == TargetArchitecture.ARM64 || defType.Context.Target.Architecture == TargetArchitecture.RiscV64)
+                else if (defType.Context.Target.Architecture == TargetArchitecture.ARM64)
                 {
                     // The Procedure Call Standard for ARM 64-bit (with SVE support) defaults to
                     // 16-byte alignment for __m256.
                     alignment = new LayoutInt(16);
                 }
+                else if (defType.Context.Target.Architecture == TargetArchitecture.RiscV64)
+                {
+                    // TODO-RISCV64: Update alignment to proper value when we implement RISC-V intrinsic.
+                    // RISC-V Vector Extenstion Intrinsic Document
+                    // https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/vector_type_infos.adoc
+                    alignment = new LayoutInt(16);
+                }
                 else
                 {
                     alignment = new LayoutInt(64);

src/coreclr/vm/methodtablebuilder.cpp

@@ -10051,6 +10051,11 @@ void MethodTableBuilder::CheckForSystemTypes()
                     // The Procedure Call Standard for ARM 64-bit (with SVE support) defaults to
                     // 16-byte alignment for __m256.
 
+                    pLayout->m_ManagedLargestAlignmentRequirementOfAllMembers = 16;
+    #elif defined(TARGET_RISCV64)
+                    // TODO-RISCV64: Update alignment to proper value when we implement RISC-V intrinsic.
+                    // RISC-V Vector Extenstion Intrinsic Document
+                    // https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/vector_type_infos.adoc
                     pLayout->m_ManagedLargestAlignmentRequirementOfAllMembers = 16;
     #else
                     pLayout->m_ManagedLargestAlignmentRequirementOfAllMembers = 32; // sizeof(__m256)
@@ -10068,6 +10073,12 @@ void MethodTableBuilder::CheckForSystemTypes()
                     // 16-byte alignment for __m256.
 
                     pLayout->m_ManagedLargestAlignmentRequirementOfAllMembers = 16;
+
+    #elif defined(TARGET_RISCV64)
+                    // TODO-RISCV64: Update alignment to proper value when we implement RISC-V intrinsic.
+                    // RISC-V Vector Extenstion Intrinsic Document
+                    // https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/vector_type_infos.adoc
+                    pLayout->m_ManagedLargestAlignmentRequirementOfAllMembers = 16;
     #else
                     pLayout->m_ManagedLargestAlignmentRequirementOfAllMembers = 64; // sizeof(__m512)
     #endif // TARGET_ARM elif TARGET_ARM64

src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector256.cs

@@ -36,6 +36,9 @@ public static unsafe class Vector256
         internal const int Alignment = 8;
 #elif TARGET_ARM64
         internal const int Alignment = 16;
+#elif TARGET_RISCV64
+        // TODO-RISCV64: Update alignment to proper value when we implement RISC-V intrinsic.
+        internal const int Alignment = 16;
 #else
         internal const int Alignment = 32;
 #endif

src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector512.cs

@@ -36,6 +36,9 @@ public static unsafe class Vector512
         internal const int Alignment = 8;
 #elif TARGET_ARM64
         internal const int Alignment = 16;
+#elif TARGET_RISCV64
+        // TODO-RISCV64: Update alignment to proper value when we implement RISC-V intrinsic.
+        internal const int Alignment = 16;
 #else
         internal const int Alignment = 64;
 #endif