[mono] Adding support for Vector128::ExtractMostSignificantBits intrinsics on amd64 (#89997)

* Extract MSB amd64

* add SSSE3 check

Author: matouskozak

src/mono/mono/arch/amd64/amd64-codegen.h

@@ -895,6 +895,7 @@ typedef union {
 
 #define amd64_sse_movsldup_reg_reg(inst,dreg,reg) emit_sse_reg_reg((inst), (dreg), (reg), 0xf3, 0x0f, 0x12)
 
+#define amd64_sse_pshufb_reg_reg(inst,dreg,reg) emit_sse_reg_reg_op4((inst), (dreg), (reg), 0x66, 0x0f, 0x38, 0x00)
 
 #define amd64_sse_pshufhw_reg_reg_imm(inst,dreg,reg,imm) emit_sse_reg_reg_imm((inst), (dreg), (reg), 0xf3, 0x0f, 0x70, (imm))
 
@@ -947,6 +948,10 @@ typedef union {
 
 #define amd64_sse_pmovmskb_reg_reg(inst,dreg,reg) emit_sse_reg_reg((inst), (dreg), (reg), 0x66, 0x0f, 0xd7)
 
+#define amd64_sse_movmskps_reg_reg(inst,dreg,reg) emit_sse_reg_reg_op2((inst), (dreg), (reg), 0x0f, 0x50)
+
+#define amd64_sse_movmskpd_reg_reg(inst,dreg,reg) emit_sse_reg_reg((inst), (dreg), (reg), 0x66, 0x0f, 0x50)
+
 
 #define amd64_sse_pand_reg_reg(inst, dreg, reg) emit_sse_reg_reg((inst), (dreg), (reg), 0x66, 0x0f, 0xdb)
 

src/mono/mono/mini/cpu-amd64.mdesc

@@ -827,6 +827,8 @@ expand_r4: dest:x src1:f len:16
 expand_r8: dest:x src1:f len:13
 xop_x_x_x: dest:x src1:x src2:x len:16 clob:1
 xop_x_x: dest:x src1:x len:16 clob:1
+sse_movmsk: dest:i src1:x len:5
+ssse3_shuffle: dest:x src1:x src2:x len:6 clob:1
 sse41_dpps_imm: dest:x src1:x src2:x len:7 clob:1
 sse41_dppd_imm: dest:x src1:x src2:x len:7 clob:1
 vector_andnot: dest:x src1:x src2:x len:7 clob:1

src/mono/mono/mini/mini-amd64.c

@@ -7521,6 +7521,23 @@ mono_arch_output_basic_block (MonoCompile *cfg, MonoBasicBlock *bb)
 			amd64_sse_movsd_reg_reg (code, ins->dreg, ins->sreg1);
 			amd64_sse_pshufd_reg_reg_imm (code, ins->dreg, ins->dreg, 0x44);
 			break;
+		case OP_SSE_MOVMSK: {
+			switch (ins->inst_c1) {
+			case MONO_TYPE_R4:
+				amd64_sse_movmskps_reg_reg (code, ins->dreg, ins->sreg1);
+				break;
+			case MONO_TYPE_R8:
+				amd64_sse_movmskpd_reg_reg (code, ins->dreg, ins->sreg1);
+				break;
+			default:
+				amd64_sse_pmovmskb_reg_reg (code, ins->dreg, ins->sreg1);
+				break;
+			}
+			break;
+		}
+		case OP_SSSE3_SHUFFLE:
+			amd64_sse_pshufb_reg_reg (code, ins->dreg, ins->sreg2);
+			break;
 		case OP_SSE41_ROUNDP: {
 			if (ins->inst_c1 == MONO_TYPE_R8)
 				amd64_sse_roundpd_reg_reg_imm (code, ins->dreg, ins->sreg1, ins->inst_c0);

src/mono/mono/mini/simd-intrinsics.c

@@ -1839,7 +1839,51 @@ emit_sri_vector (MonoCompile *cfg, MonoMethod *cmethod, MonoMethodSignature *fsi
 		}
 		return result_ins;
 #elif defined(TARGET_AMD64)
-		return NULL;
+		int type = MONO_TYPE_I1;
+
+		switch (arg0_type) {
+			case MONO_TYPE_U2:
+			case MONO_TYPE_I2: {
+				if (!is_SIMD_feature_supported (cfg, MONO_CPU_X86_SSSE3)) 
+					return NULL;
+					
+				type = type_enum_is_unsigned (arg0_type) ? MONO_TYPE_U1 : MONO_TYPE_I1;
+				MonoClass* arg_class = mono_class_from_mono_type_internal (fsig->params [0]);
+
+				guint64 shuffle_mask[2];
+				shuffle_mask[0] = 0x0F0D0B0907050301; // Place odd bytes in the lower half of vector
+				shuffle_mask[1] = 0x8080808080808080; // Zero the upper half
+
+				MonoInst* shuffle_vec = emit_xconst_v128 (cfg, arg_class, (guint8*)shuffle_mask);
+				shuffle_vec->klass = arg_class;
+
+				args [0] = emit_simd_ins (cfg, klass, OP_SSSE3_SHUFFLE, args [0]->dreg, shuffle_vec->dreg);
+				args [0]->inst_c1 = type;
+				break;
+			}
+#if TARGET_SIZEOF_VOID_P == 4
+			case MONO_TYPE_I:
+			case MONO_TYPE_U:
+#endif
+			case MONO_TYPE_U4:
+			case MONO_TYPE_I4:
+			case MONO_TYPE_R4: {
+				type = MONO_TYPE_R4;
+				break;
+			}
+#if TARGET_SIZEOF_VOID_P == 8
+			case MONO_TYPE_I:
+			case MONO_TYPE_U:
+#endif
+			case MONO_TYPE_U8:
+			case MONO_TYPE_I8:
+			case MONO_TYPE_R8: {
+				type = MONO_TYPE_R8;
+				break;
+			}
+		}
+
+		return emit_simd_ins_for_sig (cfg, klass, OP_SSE_MOVMSK, -1, type, fsig, args);
 #endif
 	}
 	case SN_GetElement: {