Attempt more optimal codegen for OpCompositeInsert.

Speculate that we can modify the SSA value in-place. As long as it is
not used after the modify, this is fine.

Also need to make sure we don't attempt to RMW something that is
impossible to modify.

3 files changed, 31 insertions, 47 deletions

diff --git a/reference/shaders-no-opt/asm/frag/inliner-dominator-inside-loop.asm.frag b/reference/shaders-no-opt/asm/frag/inliner-dominator-inside-loop.asm.frag
index ff9c122f..88b94d8c 100644
--- a/reference/shaders-no-opt/asm/frag/inliner-dominator-inside-loop.asm.frag
+++ b/reference/shaders-no-opt/asm/frag/inliner-dominator-inside-loop.asm.frag
@@ -97,36 +97,24 @@ vec4 _297;
 
 void main()
 {
-    VertexOutput _128 = _121;
+    VertexOutput _128;
     _128.HPosition = gl_FragCoord;
-    VertexOutput _130 = _128;
-    _130.Uv_EdgeDistance1 = IN_Uv_EdgeDistance1;
-    VertexOutput _132 = _130;
-    _132.UvStuds_EdgeDistance2 = IN_UvStuds_EdgeDistance2;
-    VertexOutput _134 = _132;
-    _134.Color = IN_Color;
-    VertexOutput _136 = _134;
-    _136.LightPosition_Fog = IN_LightPosition_Fog;
-    VertexOutput _138 = _136;
-    _138.View_Depth = IN_View_Depth;
-    VertexOutput _140 = _138;
-    _140.Normal_SpecPower = IN_Normal_SpecPower;
-    VertexOutput _142 = _140;
-    _142.Tangent = IN_Tangent;
-    VertexOutput _144 = _142;
-    _144.PosLightSpace_Reflectance = IN_PosLightSpace_Reflectance;
-    VertexOutput _146 = _144;
-    _146.studIndex = IN_studIndex;
-    SurfaceInput _147 = _122;
+    _128.Uv_EdgeDistance1 = IN_Uv_EdgeDistance1;
+    _128.UvStuds_EdgeDistance2 = IN_UvStuds_EdgeDistance2;
+    _128.Color = IN_Color;
+    _128.LightPosition_Fog = IN_LightPosition_Fog;
+    _128.View_Depth = IN_View_Depth;
+    _128.Normal_SpecPower = IN_Normal_SpecPower;
+    _128.Tangent = IN_Tangent;
+    _128.PosLightSpace_Reflectance = IN_PosLightSpace_Reflectance;
+    _128.studIndex = IN_studIndex;
+    SurfaceInput _147;
     _147.Color = IN_Color;
-    SurfaceInput _149 = _147;
-    _149.Uv = IN_Uv_EdgeDistance1.xy;
-    SurfaceInput _151 = _149;
-    _151.UvStuds = IN_UvStuds_EdgeDistance2.xy;
-    SurfaceInput _156 = _151;
-    _156.UvStuds.y = (fract(_151.UvStuds.y) + IN_studIndex) * 0.25;
-    float _160 = clamp(1.0 - (_146.View_Depth.w * 0.00333332992158830165863037109375), 0.0, 1.0);
-    float _163 = _146.View_Depth.w * _19.CB0.RefractionBias_FadeDistance_GlowFactor.y;
+    _147.Uv = IN_Uv_EdgeDistance1.xy;
+    _147.UvStuds = IN_UvStuds_EdgeDistance2.xy;
+    _147.UvStuds.y = (fract(_147.UvStuds.y) + IN_studIndex) * 0.25;
+    float _160 = clamp(1.0 - (_128.View_Depth.w * 0.00333332992158830165863037109375), 0.0, 1.0);
+    float _163 = _128.View_Depth.w * _19.CB0.RefractionBias_FadeDistance_GlowFactor.y;
     float _165 = clamp(1.0 - _163, 0.0, 1.0);
     vec2 _166 = IN_Uv_EdgeDistance1.xy * 1.0;
     bool _173;
@@ -174,7 +162,7 @@ void main()
     vec3 _253 = vec3(_252.x, _252.y, _232.z);
     vec2 _255 = _253.xy * _165;
     vec3 _256 = vec3(_255.x, _255.y, _253.z);
-    vec4 _268 = texture(SPIRV_Cross_CombinedStudsMapTextureStudsMapSampler, _156.UvStuds);
+    vec4 _268 = texture(SPIRV_Cross_CombinedStudsMapTextureStudsMapSampler, _147.UvStuds);
     vec3 _271 = ((IN_Color.xyz * (_193 * 1.0).xyz) * (1.0 + (_256.x * 0.300000011920928955078125))) * (_268.x * 2.0);
     vec4 _298;
     for (;;)
@@ -194,21 +182,17 @@ void main()
         break;
     }
     vec2 _303 = mix(vec2(0.800000011920928955078125, 120.0), (_298.xy * vec2(2.0, 256.0)) + vec2(0.0, 0.00999999977648258209228515625), vec2(_165));
-    Surface _304 = _125;
+    Surface _304;
     _304.albedo = _271;
-    Surface _305 = _304;
-    _305.normal = _256;
+    _304.normal = _256;
     float _306 = _303.x;
-    Surface _307 = _305;
-    _307.specular = _306;
+    _304.specular = _306;
     float _308 = _303.y;
-    Surface _309 = _307;
-    _309.gloss = _308;
+    _304.gloss = _308;
     float _312 = (_298.xy.y * _165) * 0.0;
-    Surface _313 = _309;
-    _313.reflectance = _312;
-    vec4 _318 = vec4(_271, _146.Color.w);
-    vec3 _329 = normalize(((IN_Tangent * _313.normal.x) + (cross(IN_Normal_SpecPower.xyz, IN_Tangent) * _313.normal.y)) + (IN_Normal_SpecPower.xyz * _313.normal.z));
+    _304.reflectance = _312;
+    vec4 _318 = vec4(_271, _128.Color.w);
+    vec3 _329 = normalize(((IN_Tangent * _304.normal.x) + (cross(IN_Normal_SpecPower.xyz, IN_Tangent) * _304.normal.y)) + (IN_Normal_SpecPower.xyz * _304.normal.z));
     vec3 _332 = -_19.CB0.Lamp0Dir;
     float _333 = dot(_329, _332);
     float _357 = clamp(dot(step(_19.CB0.LightConfig3.xyz, abs(IN_LightPosition_Fog.xyz - _19.CB0.LightConfig2.xyz)), vec3(1.0)), 0.0, 1.0);
@@ -217,13 +201,13 @@ void main()
     float _392 = (1.0 - (((step(_376.x, IN_PosLightSpace_Reflectance.xyz.z) * clamp(9.0 - (20.0 * abs(IN_PosLightSpace_Reflectance.xyz.z - 0.5)), 0.0, 1.0)) * _376.y) * _19.CB0.OutlineBrightness_ShadowInfo.w)) * _368.w;
     vec3 _403 = mix(_318.xyz, texture(SPIRV_Cross_CombinedEnvironmentMapTextureEnvironmentMapSampler, reflect(-IN_View_Depth.xyz, _329)).xyz, vec3(_312));
     vec3 _422 = (((_19.CB0.AmbientColor + (((_19.CB0.Lamp0Color * clamp(_333, 0.0, 1.0)) + (_19.CB0.Lamp1Color * max(-_333, 0.0))) * _392)) + _368.xyz) * vec4(_403.x, _403.y, _403.z, _318.w).xyz) + (_19.CB0.Lamp0Color * (((step(0.0, _333) * _306) * _392) * pow(clamp(dot(_329, normalize(_332 + normalize(IN_View_Depth.xyz))), 0.0, 1.0), _308)));
-    vec4 _425 = vec4(_422.x, _422.y, _422.z, _124.w);
-    _425.w = vec4(_403.x, _403.y, _403.z, _318.w).w;
+    vec4 _423 = vec4(_422.x, _422.y, _422.z, _124.w);
+    _423.w = vec4(_403.x, _403.y, _403.z, _318.w).w;
     vec2 _435 = min(IN_Uv_EdgeDistance1.wz, IN_UvStuds_EdgeDistance2.wz);
     float _439 = min(_435.x, _435.y) / _163;
-    vec3 _445 = _425.xyz * clamp((clamp((_163 * _19.CB0.OutlineBrightness_ShadowInfo.x) + _19.CB0.OutlineBrightness_ShadowInfo.y, 0.0, 1.0) * (1.5 - _439)) + _439, 0.0, 1.0);
-    vec4 _446 = vec4(_445.x, _445.y, _445.z, _425.w);
-    vec3 _453 = mix(_19.CB0.FogColor, _446.xyz, vec3(clamp(_146.LightPosition_Fog.w, 0.0, 1.0)));
+    vec3 _445 = _423.xyz * clamp((clamp((_163 * _19.CB0.OutlineBrightness_ShadowInfo.x) + _19.CB0.OutlineBrightness_ShadowInfo.y, 0.0, 1.0) * (1.5 - _439)) + _439, 0.0, 1.0);
+    vec4 _446 = vec4(_445.x, _445.y, _445.z, _423.w);
+    vec3 _453 = mix(_19.CB0.FogColor, _446.xyz, vec3(clamp(_128.LightPosition_Fog.w, 0.0, 1.0)));
     _entryPointOutput = vec4(_453.x, _453.y, _453.z, _446.w);
 }
 
diff --git a/reference/shaders-no-opt/asm/frag/switch-single-case-multiple-exit-cfg.asm.frag b/reference/shaders-no-opt/asm/frag/switch-single-case-multiple-exit-cfg.asm.frag
index 2f7fee64..2ec47169 100644
--- a/reference/shaders-no-opt/asm/frag/switch-single-case-multiple-exit-cfg.asm.frag
+++ b/reference/shaders-no-opt/asm/frag/switch-single-case-multiple-exit-cfg.asm.frag
@@ -16,7 +16,7 @@ void main()
             _30 = _19;
             break;
         }
-        highp vec2 _29 = _19;
+        highp vec2 _29;
         _29.y = _19.y;
         _30 = _29;
         break;
diff --git a/reference/shaders-no-opt/legacy/frag/switch-single-case-multiple-exit-cfg.legacy.asm.frag b/reference/shaders-no-opt/legacy/frag/switch-single-case-multiple-exit-cfg.legacy.asm.frag
index be41ceef..f46bc2fd 100644
--- a/reference/shaders-no-opt/legacy/frag/switch-single-case-multiple-exit-cfg.legacy.asm.frag
+++ b/reference/shaders-no-opt/legacy/frag/switch-single-case-multiple-exit-cfg.legacy.asm.frag
@@ -14,7 +14,7 @@ void main()
             _30 = _19;
             break;
         }
-        highp vec2 _29 = _19;
+        highp vec2 _29;
         _29.y = _19.y;
         _30 = _29;
         break;