GS/SW: Use non-saturating ARM instructions for color gradient setup.

This is more efficient on ARM, though the equivalent instructions are not currently used in the x64 JIT and C++ versions of GSVector.

Co-authored-by: TellowKrinkle

Author: TJnotJT

pcsx2/GS/Renderers/SW/GSSetupPrimCodeGenerator.arm64.cpp

@@ -225,17 +225,13 @@ void GSSetupPrimCodeGenerator::Color()
 		// GSVector4 c = dscan.c;
 		armAsm->Ldr(v16, MemOperand(_dscan, offsetof(GSVertexSW, c)));
 
-		// constexpr VectorI mask16 = VectorI::cxpr(0xFFFF);
-		armAsm->Movi(v17.V4S(), 0xFFFF);
-
-		// local.d4.c = (GSVector4i(dscan.c * step_shift) & mask16).xzyw().pu32();
+		// GSVector4i tmp = GSVector4i(dscan.c * step_shift).xzyw();
+		// local.d4.c = tmp.uzp1_16(tmp); // Not currently in GSVector since that's mainly targeting x86 for now
 		armAsm->Fmul(v2.V4S(), v16.V4S(), v3.V4S());
 		armAsm->Fcvtzs(v2.V4S(), v2.V4S());
-		armAsm->And(v2.V4S(), v17.V4S());
 		armAsm->Rev64(_vscratch.V4S(), v2.V4S());
 		armAsm->Uzp1(v2.V4S(), v2.V4S(), _vscratch.V4S());
-		armAsm->Uqxtn(v2.V4H(), v2.V4S());
-		armAsm->Dup(v2.V2D(), v2.V2D(), 0);
+		armAsm->Uzp1(v2.V8H(), v2.V8H(), v2.V8H());
 		armAsm->Str(v2, MemOperand(_locals, offsetof(GSScanlineLocalData, d4.c)));
 
 		// GSVector4 dr = c.xxxx();
@@ -246,25 +242,18 @@ void GSSetupPrimCodeGenerator::Color()
 
 		for (int i = 0; i < (m_sel.notest ? 1 : 4); i++)
 		{
-			// VectorI r = (VectorI(dr * shift[1 + i]) & mask16).pu32();
+			// VectorI r = VectorI(dr * shift[1 + i]);
 
 			armAsm->Fmul(v2.V4S(), v0.V4S(), VRegister(4 + i, kFormat4S));
 			armAsm->Fcvtzs(v2.V4S(), v2.V4S());
-			armAsm->And(v2.V4S(), v17.V4S());
-			armAsm->Uqxtn(v2.V4H(), v2.V4S());
-			armAsm->Dup(v2.V2D(), v2.V2D(), 0);
 
-			// VectorI b = (VectorI(db * shift[1 + i]) & mask16).pu32();
+			// VectorI b = VectorI(db * shift[1 + i]);
 
 			armAsm->Fmul(v3.V4S(), v1.V4S(), VRegister(4 + i, kFormat4S));
 			armAsm->Fcvtzs(v3.V4S(), v3.V4S());
-			armAsm->And(v3.V4S(), v17.V4S());
-			armAsm->Uqxtn(v3.V4H(), v3.V4S());
-			armAsm->Dup(v3.V2D(), v3.V2D(), 0);
-
-			// m_local.d[i].rb = r.upl16(b);
 
-			armAsm->Zip1(v2.V8H(), v2.V8H(), v3.V8H());
+			// m_local.d[i].rb = r.trn1_16(b); // Not currently in GSVector since that's mainly targeting x86 for now
+			armAsm->Trn1(v2.V8H(), v2.V8H(), v3.V8H());
 			armAsm->Str(v2, _local(d[i].rb));
 		}
 
@@ -278,25 +267,19 @@ void GSSetupPrimCodeGenerator::Color()
 
 		for (int i = 0; i < (m_sel.notest ? 1 : 4); i++)
 		{
-			// VectorI g = (VectorI(dg * shift[1 + i]) & mask16).pu32();
+			// VectorI g = VectorI(dg * shift[1 + i]);
 
 			armAsm->Fmul(v2.V4S(), v0.V4S(), VRegister(4 + i, kFormat4S));
 			armAsm->Fcvtzs(v2.V4S(), v2.V4S());
-			armAsm->And(v2.V4S(), v17.V4S());
-			armAsm->Uqxtn(v2.V4H(), v2.V4S());
-			armAsm->Dup(v2.V2D(), v2.V2D(), 0);
 
-			// VectorI a = (VectorI(da * shift[1 + i]) & mask16).pu32();
+			// VectorI a = VectorI(da * shift[1 + i]);
 
 			armAsm->Fmul(v3.V4S(), v1.V4S(), VRegister(4 + i, kFormat4S));
 			armAsm->Fcvtzs(v3.V4S(), v3.V4S());
-			armAsm->And(v3.V4S(), v17.V4S());
-			armAsm->Uqxtn(v3.V4H(), v3.V4S());
-			armAsm->Dup(v3.V2D(), v3.V2D(), 0);
 
-			// m_local.d[i].ga = g.upl16(a);
+			// m_local.d[i].ga = g.trn1_16(a); // Not currently in GSVector since that's mainly targeting x86 for now
 
-			armAsm->Zip1(v2.V8H(), v2.V8H(), v3.V8H());
+			armAsm->Trn1(v2.V8H(), v2.V8H(), v3.V8H());
 			armAsm->Str(v2, _local(d[i].ga));
 		}
 	}