IR: Implement VectorPopulationCount

src/backend_x64/emit_x64_vector.cpp

@@ -8,6 +8,7 @@
 #include "backend_x64/block_of_code.h"
 #include "backend_x64/emit_x64.h"
 #include "common/assert.h"
+#include "common/bit_util.h"
 #include "common/common_types.h"
 #include "common/mp.h"
 #include "frontend/ir/basic_block.h"
@@ -882,6 +883,39 @@ void EmitX64::EmitVectorPairedAdd64(EmitContext& ctx, IR::Inst* inst) {
     ctx.reg_alloc.DefineValue(inst, a);
 }
 
+void EmitX64::EmitVectorPopulationCount(EmitContext& ctx, IR::Inst* inst) {
+    if (code.DoesCpuSupport(Xbyak::util::Cpu::tSSSE3)) {
+        auto args = ctx.reg_alloc.GetArgumentInfo(inst);
+
+        Xbyak::Xmm low_a = ctx.reg_alloc.UseScratchXmm(args[0]);
+        Xbyak::Xmm high_a = ctx.reg_alloc.ScratchXmm();
+        Xbyak::Xmm tmp1 = ctx.reg_alloc.ScratchXmm();
+        Xbyak::Xmm tmp2 = ctx.reg_alloc.ScratchXmm();
+
+        code.movdqa(high_a, low_a);
+        code.psrlw(high_a, 4);
+        code.movdqa(tmp1, code.MConst(0x0F0F0F0F0F0F0F0F, 0x0F0F0F0F0F0F0F0F));
+        code.pand(high_a, tmp1); // High nibbles
+        code.pand(low_a, tmp1); // Low nibbles
+
+        code.movdqa(tmp1, code.MConst(0x0302020102010100, 0x0403030203020201));
+        code.movdqa(tmp2, tmp1);
+        code.pshufb(tmp1, low_a);
+        code.pshufb(tmp2, high_a);
+
+        code.paddb(tmp1, tmp2);
+
+        ctx.reg_alloc.DefineValue(inst, tmp1);
+        return;
+    }
+
+    EmitTwoArgumentFallback(code, ctx, inst, [](std::array<u8, 16>& result, const std::array<u8, 16>& a){
+        for (size_t i = 0; i < 16; ++i) {
+            result[i] = static_cast<u8>(Common::BitCount(a[i]));
+        }
+    });
+}
+
 void EmitX64::EmitVectorSub8(EmitContext& ctx, IR::Inst* inst) {
     EmitVectorOperation(code, ctx, inst, &Xbyak::CodeGenerator::psubb);
 }

src/frontend/ir/ir_emitter.cpp

@@ -977,6 +977,10 @@ U128 IREmitter::VectorPairedAdd(size_t esize, const U128& a, const U128& b) {
     return {};
 }
 
+U128 IREmitter::VectorPopulationCount(const U128& a) {
+    return Inst<U128>(Opcode::VectorPopulationCount, a);
+}
+
 U128 IREmitter::VectorSub(size_t esize, const U128& a, const U128& b) {
     switch (esize) {
     case 8:

src/frontend/ir/ir_emitter.h

@@ -223,6 +223,7 @@ public:
     U128 VectorOr(const U128& a, const U128& b);
     U128 VectorPairedAdd(size_t esize, const U128& a, const U128& b);
     U128 VectorPairedAddLower(size_t esize, const U128& a, const U128& b);
+    U128 VectorPopulationCount(const U128& a);
     U128 VectorSub(size_t esize, const U128& a, const U128& b);
     U128 VectorZeroExtend(size_t original_esize, const U128& a);
     U128 VectorZeroUpper(const U128& a);

src/frontend/ir/opcodes.inc

@@ -248,6 +248,7 @@ OPCODE(VectorPairedAdd8,            T::U128,        T::U128,        T::U128
 OPCODE(VectorPairedAdd16,           T::U128,        T::U128,        T::U128                         )
 OPCODE(VectorPairedAdd32,           T::U128,        T::U128,        T::U128                         )
 OPCODE(VectorPairedAdd64,           T::U128,        T::U128,        T::U128                         )
+OPCODE(VectorPopulationCount,       T::U128,        T::U128                                         )
 OPCODE(VectorSub8,                  T::U128,        T::U128,        T::U128                         )
 OPCODE(VectorSub16,                 T::U128,        T::U128,        T::U128                         )
 OPCODE(VectorSub32,                 T::U128,        T::U128,        T::U128                         )