Performance
Android Features
Lit shaders were optimized for android first, using half precision wherever possible. Certain features are automatically disabled when using the Android build target, for example the Height Map, LTCGI etc. These features can also have a heavy impact on PC, due to high resolutions in VR, and all the calculations being done per pixel. The number of steps of the Height Map increases the number of time the Height Map will get sampled. The more pixels on a screen the material covers, the higher the performance impact will be.
Directional Light
Unity assumes that one directional light is always active in the scene and doesn't have any keywords to disable and skip calculations when its not used. This can have a noticeable impact on Android (mostly the Specular Highlights math), so in certain cases, like when using a lightmap, the directional light is disabled. This is also slightly wasteful on PC, so a dynamic branch is used to skip directional lights when they're disabled. Without a dynamic branch, both sides are evaluated, and the result is selected conditionally.
Compiled Code Example
Line 50
If directional light is disabled this huge chunk of instructions is skipped until line 103.
Line 108
Light Probe Proxy Volumes use a dynamic branch on all materials without lightmaps enabled. To save space disable them in the config file Tools > Lit > Create Config File.
Line 168
This branch is used for reflection probes, if the second probe needs be sampled and blended with the first one. Some shaders also have a branch for the box projection, but this shader assumes box projection on average is enabled, to skip the overhead of a branch.
0: sample_indexable(texture2d)(float,float,float,float) r0.xyz, v4.xyxx, t3.xyzw, s2
1: mul r0.xyz, r0.xyzx, cb0[5].xyzx
2: add r1.xy, -cb0[7].xyxx, l(1.000000, 1.000000, 0.000000, 0.000000)
3: add r0.w, -r1.x, l(1.000000)
4: deriv_rtx_coarse r1.xzw, v2.xxyz
5: deriv_rty_coarse r2.xyz, v2.xyzx
6: dp3 r1.x, r1.xzwx, r1.xzwx
7: dp3 r1.z, r2.xyzx, r2.xyzx
8: add r1.x, r1.z, r1.x
9: mul r0.w, r0.w, r0.w
10: dp2 r1.x, cb0[15].wwww, r1.xxxx
11: min r1.x, r1.x, cb0[16].x
12: mad_sat r0.w, r0.w, r0.w, r1.x
13: sqrt r0.w, r0.w
14: sqrt r0.w, r0.w
15: add r0.w, -r0.w, l(1.000000)
16: dp3 r1.x, v2.xyzx, v2.xyzx
17: max r1.x, r1.x, l(0.000000)
18: rsq r1.x, r1.x
19: mul r2.xyz, r1.xxxx, v2.xyzx
20: mov r1.z, v5.y
21: add r3.xyz, -v1.xyzx, cb2[r1.z + 64].xyzx
22: dp3 r1.z, r3.xyzx, r3.xyzx
23: rsq r1.z, r1.z
24: mul r3.xyz, r1.zzzz, r3.xyzx
25: dp3 r1.z, r2.xyzx, r3.xyzx
26: add r4.x, |r1.z|, l(0.000010)
27: add r4.y, -r0.w, l(1.000000)
28: mul r0.w, cb0[16].z, cb0[16].z
29: mul r0.w, r0.w, l(0.160000)
30: mul r5.xyz, r0.xyzx, cb0[7].yyyy
31: mad r5.xyz, r0.wwww, r1.yyyy, r5.xyzx
32: sample_l_indexable(texture2d)(float,float,float,float) r1.zw, r4.xyxx, t4.zwxy, s3, l(0.000000)
33: add r0.w, -r1.z, r1.w
34: mad r6.xyz, r5.xyzx, r0.wwww, r1.zzzz
35: div r0.w, l(1.000000, 1.000000, 1.000000, 1.000000), r1.w
36: add r0.w, r0.w, l(-1.000000)
37: mad r7.xyz, r5.xyzx, r0.wwww, l(1.000000, 1.000000, 1.000000, 0.000000)
38: dp3 r0.w, -r3.xyzx, r2.xyzx
39: add r0.w, r0.w, r0.w
40: mad r8.xyz, r2.xyzx, -r0.wwww, -r3.xyzx
41: mul r0.w, r4.y, r4.y
42: mad r1.xzw, v2.xxyz, r1.xxxx, -r8.xxyz
43: mad r1.xzw, r0.wwww, r1.xxzw, r8.xxyz
44: dp3 r3.w, cb1[0].xyzx, cb1[0].xyzx
45: max r3.w, r3.w, l(0.000000)
46: rsq r3.w, r3.w
47: mul r8.xyz, r3.wwww, cb1[0].xyzx
48: dp3 r4.z, r8.xyzx, r8.xyzx
49: ne r4.z, r4.z, l(0.000000)
50: if_nz r4.z
51: mad r3.xyz, cb1[0].xyzx, r3.wwww, r3.xyzx
52: dp3 r3.w, r3.xyzx, r3.xyzx
53: rsq r3.w, r3.w
54: mul r3.xyz, r3.wwww, r3.xyzx
55: dp3_sat r3.w, r2.xyzx, r8.xyzx
56: dp3_sat r4.z, r8.xyzx, r3.xyzx
57: dp3_sat r3.x, r2.xyzx, r3.xyzx
58: mul r8.xyz, r3.wwww, cb0[1].xyzx
59: mul r3.y, r4.z, r4.z
60: dp2 r3.y, r3.yyyy, r4.yyyy
61: add r3.y, r3.y, l(-0.500000)
62: add r3.z, -r3.w, l(1.000000)
63: mul r4.w, r3.z, r3.z
64: mul r4.w, r4.w, r4.w
65: mul r3.z, r3.z, r4.w
66: mad r3.z, r3.y, r3.z, l(1.000000)
67: add r4.w, -r4.x, l(1.000000)
68: mul r5.w, r4.w, r4.w
69: mul r5.w, r5.w, r5.w
70: mul r4.w, r4.w, r5.w
71: mad r3.y, r3.y, r4.w, l(1.000000)
72: mul r3.y, r3.y, r3.z
73: mul r8.xyz, r3.yyyy, r8.xyzx
74: max r0.w, r0.w, l(0.002000)
75: add r9.xyz, -r5.xyzx, l(1.000000, 1.000000, 1.000000, 0.000000)
76: add r3.y, -r4.z, l(1.000000)
77: mul r3.z, r3.y, r3.y
78: mul r3.z, r3.z, r3.z
79: mul r3.y, r3.z, r3.y
80: mad r5.xyz, r9.xyzx, r3.yyyy, r5.xyzx
81: mul r5.xyz, r7.xyzx, r5.xyzx
82: mul r3.y, r0.w, r3.x
83: mad r3.x, -r3.x, r3.x, l(1.000000)
84: mad r3.x, r3.y, r3.y, r3.x
85: div r3.x, r0.w, r3.x
86: mul r3.x, r3.x, r3.x
87: mul r3.x, r3.x, l(0.318310)
88: mul r3.y, r0.w, r0.w
89: mul r3.z, r4.x, r4.x
90: mad r0.w, -r0.w, r0.w, l(1.000000)
91: mad r3.z, r3.z, r0.w, r3.y
92: sqrt r3.z, r3.z
93: mul r4.z, r3.w, r3.w
94: mad r0.w, r4.z, r0.w, r3.y
95: sqrt r0.w, r0.w
96: mul r0.w, r0.w, r4.x
97: mad r0.w, r3.w, r3.z, r0.w
98: div r0.w, l(0.500000), r0.w
99: mul r0.w, r0.w, r3.x
100: mul r3.xyz, r5.xyzx, r0.wwww
101: max r3.xyz, r3.xyzx, l(0.000000, 0.000000, 0.000000, 0.000000)
102: mul r3.xyz, r8.xyzx, r3.xyzx
103: else
104: mov r8.xyz, l(0,0,0,0)
105: mov r3.xyz, l(0,0,0,0)
106: endif
107: eq r0.w, cb4[0].x, l(1.000000)
108: if_nz r0.w
109: eq r0.w, cb4[0].y, l(1.000000)
110: mul r4.xzw, v1.yyyy, cb4[2].xxyz
111: mad r4.xzw, cb4[1].xxyz, v1.xxxx, r4.xxzw
112: mad r4.xzw, cb4[3].xxyz, v1.zzzz, r4.xxzw
113: add r4.xzw, r4.xxzw, cb4[4].xxyz
114: movc r4.xzw, r0.wwww, r4.xxzw, v1.xxyz
115: add r4.xzw, r4.xxzw, -cb4[6].xxyz
116: mul r5.yzw, r4.xxzw, cb4[5].xxyz
117: mul r0.w, r5.y, l(0.250000)
118: mul r3.w, cb4[0].z, l(0.500000)
119: mad r4.x, -cb4[0].z, l(0.500000), l(0.250000)
120: max r0.w, r0.w, r3.w
121: min r5.x, r4.x, r0.w
122: sample_indexable(texture3d)(float,float,float,float) r9.xyzw, r5.xzwx, t2.xyzw, s1
123: add r4.xzw, r5.xxzw, l(0.250000, 0.000000, 0.000000, 0.000000)
124: sample_indexable(texture3d)(float,float,float,float) r10.xyzw, r4.xzwx, t2.xyzw, s1
125: add r4.xzw, r5.xxzw, l(0.500000, 0.000000, 0.000000, 0.000000)
126: sample_indexable(texture3d)(float,float,float,float) r5.xyzw, r4.xzwx, t2.xyzw, s1
127: mov r2.w, l(1.000000)
128: dp4 r9.x, r9.xyzw, r2.xyzw
129: dp4 r9.y, r10.xyzw, r2.xyzw
130: dp4 r9.z, r5.xyzw, r2.xyzw
131: else
132: mov r2.w, l(1.000000)
133: dp4 r9.x, cb1[39].xyzw, r2.xyzw
134: dp4 r9.y, cb1[40].xyzw, r2.xyzw
135: dp4 r9.z, cb1[41].xyzw, r2.xyzw
136: endif
137: mul r5.xyzw, r2.yzzx, r2.xyzz
138: dp4 r10.x, cb1[42].xyzw, r5.xyzw
139: dp4 r10.y, cb1[43].xyzw, r5.xyzw
140: dp4 r10.z, cb1[44].xyzw, r5.xyzw
141: mul r0.w, r2.y, r2.y
142: mad r0.w, r2.x, r2.x, -r0.w
143: mad r4.xzw, cb1[45].xxyz, r0.wwww, r10.xxyz
144: add r4.xzw, r4.xxzw, r9.xxyz
145: max r4.xzw, r4.xxzw, l(0.000000, 0.000000, 0.000000, 0.000000)
146: lt r0.w, l(0.000000), cb3[2].w
147: lt r5.xyz, l(0.000000, 0.000000, 0.000000, 0.000000), r1.xzwx
148: movc r9.xyz, r5.xyzx, cb3[0].xyzx, cb3[1].xyzx
149: add r9.xyz, r9.xyzx, -v1.xyzx
150: div r9.xyz, r9.xyzx, r1.xzwx
151: min r2.w, r9.y, r9.x
152: min r2.w, r9.z, r2.w
153: add r9.xyz, v1.xyzx, -cb3[2].xyzx
154: mad r9.xyz, r1.xzwx, r2.wwww, r9.xyzx
155: movc r9.xyz, r0.wwww, r9.xyzx, r1.xzwx
156: mad r0.w, -r4.y, l(0.700000), l(1.700000)
157: mul r0.w, r0.w, r4.y
158: mul r0.w, r0.w, l(6.000000)
159: sample_l_indexable(texturecube)(float,float,float,float) r9.xyzw, r9.xyzx, t0.xyzw, s0, r0.w
160: add r2.w, r9.w, l(-1.000000)
161: mad r2.w, cb3[3].w, r2.w, l(1.000000)
162: log r2.w, r2.w
163: mul r2.w, r2.w, cb3[3].y
164: exp r2.w, r2.w
165: mul r2.w, r2.w, cb3[3].x
166: mul r10.xyz, r9.xyzx, r2.wwww
167: lt r3.w, cb3[1].w, l(0.999990)
168: if_nz r3.w
169: lt r3.w, l(0.000000), cb3[6].w
170: movc r5.xyz, r5.xyzx, cb3[4].xyzx, cb3[5].xyzx
171: add r5.xyz, r5.xyzx, -v1.xyzx
172: div r5.xyz, r5.xyzx, r1.xzwx
173: min r4.y, r5.y, r5.x
174: min r4.y, r5.z, r4.y
175: add r5.xyz, v1.xyzx, -cb3[6].xyzx
176: mad r5.xyz, r1.xzwx, r4.yyyy, r5.xyzx
177: movc r5.xyz, r3.wwww, r5.xyzx, r1.xzwx
178: sample_l_indexable(texturecube)(float,float,float,float) r5.xyzw, r5.xyzx, t1.xyzw, s0, r0.w
179: add r0.w, r5.w, l(-1.000000)
180: mad r0.w, cb3[7].w, r0.w, l(1.000000)
181: log r0.w, r0.w
182: mul r0.w, r0.w, cb3[7].y
183: exp r0.w, r0.w
184: mul r0.w, r0.w, cb3[7].x
185: mul r5.xyz, r5.xyzx, r0.wwww
186: mad r9.xyz, r2.wwww, r9.xyzx, -r5.xyzx
187: mad r10.xyz, cb3[1].wwww, r9.xyzx, r5.xyzx
188: endif
189: dp3 r0.w, r1.xzwx, r2.xyzx
190: add r0.w, r0.w, l(1.000000)
191: min r0.w, r0.w, l(1.000000)
192: mul r0.w, r0.w, r0.w
193: mul r1.xzw, r0.wwww, r10.xxyz
194: add r2.xyz, r8.xyzx, r4.xzwx
195: dp3 r0.w, r2.xyzx, l(1.000000, 1.000000, 1.000000, 0.000000)
196: sqrt r0.w, r0.w
197: add r0.w, r0.w, l(-1.000000)
198: mad_sat r0.w, cb0[9].w, r0.w, l(1.000000)
199: mul r1.xzw, r0.wwww, r1.xxzw
200: mul r4.xyz, r6.xyzx, r7.xyzx
201: mul r1.xzw, r1.xxzw, r4.xxyz
202: mul r0.xyz, r0.xyzx, r1.yyyy
203: mad r0.xyz, r0.xyzx, r2.xyzx, r1.xzwx
204: mad o0.xyz, r3.xyzx, l(3.141593, 3.141593, 3.141593, 0.000000), r0.xyzx
205: mov o0.w, l(1.000000)
206: ret