GS/HW: Adjust when blend second pass is enabled.

If texture barriers are supported don't enable it at all.
Remove blend second pass from Metal, no need as texture copies are always enabled.

pcsx2/GS/Renderers/HW/GSRendererHW.cpp

@@ -4017,13 +4017,13 @@ void GSRendererHW::EmulateBlending(int rt_alpha_min, int rt_alpha_max, bool& DAT
 	const bool no_prim_overlap = (m_prim_overlap == PRIM_OVERLAP_NO);
 
 	// HW blend can be done in multiple passes when there's no overlap.
-	// Render passes are faster than copies so what we can do is trade the same number
-	// of copies that would've been used for SW blend for the same number of draw calls instead.
-	// It is a middle ground between accuracy and speed, higher blend levels will still prefer sw blend.
-	//const bool bmix1_second_pass_1 = no_prim_overlap && blend_mix1 && m_conf.ps.blend_a == m_conf.ps.blend_d;
-	const bool bmix1_second_pass = no_prim_overlap && blend_mix1 && (alpha_c0_high_max_one || alpha_c1_high_max_one || alpha_c2_high_one) && m_conf.ps.blend_d == 2;
+	// Blend second pass is only useful when texture barriers aren't supported.
+	// Speed wise Texture barriers > blend second pass > texture copies.
+	// TODO: 24bit and 32bit formats on clamp 1 can always prefer blend second pass depending on the blend equations.
+	const bool blend_second_pass_support = !features.texture_barrier && no_prim_overlap && is_basic_blend;
+	const bool bmix1_second_pass = blend_second_pass_support && blend_mix1 && (alpha_c0_high_max_one || alpha_c2_high_one) && m_conf.ps.blend_d == 2;
 	// We don't want to enable blend mix if we are doing a second pass, it's useless.
-	blend_mix &= !bmix1_second_pass; 
+	blend_mix &= !bmix1_second_pass;
 
 	const bool one_barrier = m_conf.require_one_barrier || blend_ad_alpha_masked;
 	// Condition 1: Require full sw blend for full barrier.
@@ -4399,7 +4399,8 @@ void GSRendererHW::EmulateBlending(int rt_alpha_min, int rt_alpha_max, bool& DAT
 		{
 			m_conf.ps.blend_hw = 3;
 		}
-		else if (is_basic_blend && no_prim_overlap)
+
+		if (blend_second_pass_support)
 		{
 			const HWBlend blend_second_pass = GSDevice::GetBlend(blend_index);
 			if ((alpha_c0_high_max_one || alpha_c2_high_one) && (blend_flag & BLEND_HW4))

pcsx2/GS/Renderers/Metal/GSDeviceMTL.mm

@@ -2213,15 +2213,6 @@ static bool usesStencil(GSHWDrawConfig::DestinationAlphaMode dstalpha)
 
 	SendHWDraw(config, mtlenc, index_buffer, index_buffer_offset);
 
-	if (config.blend_second_pass.enable)
-	{
-		if (config.blend_second_pass.blend.constant_enable)
-			MRESetBlendColor(config.blend_second_pass.blend.constant);
-		config.ps.blend_hw = config.blend_second_pass.blend_hw;
-		MRESetHWPipelineState(config.vs, config.ps, config.blend_second_pass.blend, config.colormask);
-		SendHWDraw(config, mtlenc, index_buffer, index_buffer_offset);
-	}
-
 	if (config.alpha_second_pass.enable)
 	{
 		if (config.alpha_second_pass.ps_aref != config.cb_ps.FogColor_AREF.a)