Fix SwitchWithFallthrough test on iOS.

It looks like returning from inside a switch on iOS gives wrong results
in GLSL.

Change-Id: I9d6d8971a7a54600268e27443815444fca6f3c61
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/450994
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>

resources/sksl/shared/SwitchWithFallthrough.sksl

@@ -1,22 +1,26 @@
 uniform half4 colorGreen, colorRed;
 
 bool switch_fallthrough(int value) {
+    bool ok = false;
     switch (value) {
-        case 2:  return false;
+        case 2:  break;
         case 1:
-        case 0:  return true;
-        default: return false;
+        case 0:  ok = true; break;
+        default: break;
     }
+    return ok;
 }
 
 bool switch_fallthrough_twice(int value) {
+    bool ok = false;
     switch (value) {
-        case 0:  return false;
+        case 0:  break;
         case 1:
         case 2:
-        case 3:  return true;
-        default: return false;
+        case 3:  ok = true; break;
+        default: break;
     }
+    return ok;
 }
 
 half4 main(float2 coords) {

tests/sksl/shared/SwitchWithFallthrough.asm.frag

@@ -9,10 +9,11 @@ OpName %_UniformBuffer "_UniformBuffer"
 OpMemberName %_UniformBuffer 0 "colorGreen"
 OpMemberName %_UniformBuffer 1 "colorRed"
 OpName %_entrypoint_v "_entrypoint_v"
-OpName %switch_fallthrough_bi "switch_fallthrough_bi"
 OpName %switch_fallthrough_twice_bi "switch_fallthrough_twice_bi"
+OpName %ok "ok"
 OpName %main "main"
 OpName %x "x"
+OpName %_0_ok "_0_ok"
 OpDecorate %sk_FragColor RelaxedPrecision
 OpDecorate %sk_FragColor Location 0
 OpDecorate %sk_FragColor Index 0
@@ -22,13 +23,15 @@ OpMemberDecorate %_UniformBuffer 0 RelaxedPrecision
 OpMemberDecorate %_UniformBuffer 1 Offset 16
 OpMemberDecorate %_UniformBuffer 1 RelaxedPrecision
 OpDecorate %_UniformBuffer Block
-OpDecorate %12 Binding 0
-OpDecorate %12 DescriptorSet 0
-OpDecorate %54 RelaxedPrecision
-OpDecorate %55 RelaxedPrecision
-OpDecorate %72 RelaxedPrecision
+OpDecorate %11 Binding 0
+OpDecorate %11 DescriptorSet 0
+OpDecorate %40 RelaxedPrecision
+OpDecorate %48 RelaxedPrecision
+OpDecorate %49 RelaxedPrecision
+OpDecorate %58 RelaxedPrecision
+OpDecorate %71 RelaxedPrecision
+OpDecorate %74 RelaxedPrecision
 OpDecorate %75 RelaxedPrecision
-OpDecorate %76 RelaxedPrecision
 %float = OpTypeFloat 32
 %v4float = OpTypeVector %float 4
 %_ptr_Output_v4float = OpTypePointer Output %v4float
@@ -38,104 +41,104 @@ OpDecorate %76 RelaxedPrecision
 %sk_Clockwise = OpVariable %_ptr_Input_bool Input
 %_UniformBuffer = OpTypeStruct %v4float %v4float
 %_ptr_Uniform__UniformBuffer = OpTypePointer Uniform %_UniformBuffer
-%12 = OpVariable %_ptr_Uniform__UniformBuffer Uniform
+%11 = OpVariable %_ptr_Uniform__UniformBuffer Uniform
 %void = OpTypeVoid
-%17 = OpTypeFunction %void
+%16 = OpTypeFunction %void
 %v2float = OpTypeVector %float 2
 %float_0 = OpConstant %float 0
-%21 = OpConstantComposite %v2float %float_0 %float_0
+%20 = OpConstantComposite %v2float %float_0 %float_0
 %_ptr_Function_v2float = OpTypePointer Function %v2float
 %int = OpTypeInt 32 1
 %_ptr_Function_int = OpTypePointer Function %int
-%26 = OpTypeFunction %bool %_ptr_Function_int
+%25 = OpTypeFunction %bool %_ptr_Function_int
+%_ptr_Function_bool = OpTypePointer Function %bool
 %false = OpConstantFalse %bool
 %true = OpConstantTrue %bool
-%47 = OpTypeFunction %v4float %_ptr_Function_v2float
+%41 = OpTypeFunction %v4float %_ptr_Function_v2float
 %_ptr_Uniform_v4float = OpTypePointer Uniform %v4float
 %int_0 = OpConstant %int 0
 %_ptr_Function_v4float = OpTypePointer Function %v4float
 %int_1 = OpConstant %int 1
-%_entrypoint_v = OpFunction %void None %17
-%18 = OpLabel
-%22 = OpVariable %_ptr_Function_v2float Function
-OpStore %22 %21
-%24 = OpFunctionCall %v4float %main %22
-OpStore %sk_FragColor %24
+%_entrypoint_v = OpFunction %void None %16
+%17 = OpLabel
+%21 = OpVariable %_ptr_Function_v2float Function
+OpStore %21 %20
+%23 = OpFunctionCall %v4float %main %21
+OpStore %sk_FragColor %23
 OpReturn
 OpFunctionEnd
-%switch_fallthrough_bi = OpFunction %bool None %26
-%28 = OpFunctionParameter %_ptr_Function_int
-%29 = OpLabel
-%30 = OpLoad %int %28
-OpSelectionMerge %31 None
-OpSwitch %30 %35 2 %32 1 %33 0 %34
-%32 = OpLabel
-OpReturnValue %false
-%33 = OpLabel
-OpBranch %34
+%switch_fallthrough_twice_bi = OpFunction %bool None %25
+%27 = OpFunctionParameter %_ptr_Function_int
+%28 = OpLabel
+%ok = OpVariable %_ptr_Function_bool Function
+OpStore %ok %false
+%32 = OpLoad %int %27
+OpSelectionMerge %33 None
+OpSwitch %32 %38 0 %34 1 %35 2 %36 3 %37
 %34 = OpLabel
-OpReturnValue %true
+OpBranch %33
 %35 = OpLabel
-OpReturnValue %false
-%31 = OpLabel
-OpUnreachable
+OpBranch %36
+%36 = OpLabel
+OpBranch %37
+%37 = OpLabel
+OpStore %ok %true
+OpBranch %33
+%38 = OpLabel
+OpBranch %33
+%33 = OpLabel
+%40 = OpLoad %bool %ok
+OpReturnValue %40
 OpFunctionEnd
-%switch_fallthrough_twice_bi = OpFunction %bool None %26
-%38 = OpFunctionParameter %_ptr_Function_int
-%39 = OpLabel
-%40 = OpLoad %int %38
-OpSelectionMerge %41 None
-OpSwitch %40 %46 0 %42 1 %43 2 %44 3 %45
-%42 = OpLabel
-OpReturnValue %false
+%main = OpFunction %v4float None %41
+%42 = OpFunctionParameter %_ptr_Function_v2float
 %43 = OpLabel
-OpBranch %44
-%44 = OpLabel
-OpBranch %45
-%45 = OpLabel
-OpReturnValue %true
-%46 = OpLabel
-OpReturnValue %false
-%41 = OpLabel
-OpUnreachable
-OpFunctionEnd
-%main = OpFunction %v4float None %47
-%48 = OpFunctionParameter %_ptr_Function_v2float
-%49 = OpLabel
 %x = OpVariable %_ptr_Function_int Function
-%58 = OpVariable %_ptr_Function_int Function
-%63 = OpVariable %_ptr_Function_int Function
-%66 = OpVariable %_ptr_Function_v4float Function
-%51 = OpAccessChain %_ptr_Uniform_v4float %12 %int_0
-%54 = OpLoad %v4float %51
-%55 = OpCompositeExtract %float %54 1
-%56 = OpConvertFToS %int %55
-OpStore %x %56
-%57 = OpLoad %int %x
-OpStore %58 %57
-%59 = OpFunctionCall %bool %switch_fallthrough_bi %58
-OpSelectionMerge %61 None
-OpBranchConditional %59 %60 %61
+%_0_ok = OpVariable %_ptr_Function_bool Function
+%62 = OpVariable %_ptr_Function_int Function
+%65 = OpVariable %_ptr_Function_v4float Function
+%45 = OpAccessChain %_ptr_Uniform_v4float %11 %int_0
+%48 = OpLoad %v4float %45
+%49 = OpCompositeExtract %float %48 1
+%50 = OpConvertFToS %int %49
+OpStore %x %50
+OpStore %_0_ok %false
+%52 = OpLoad %int %x
+OpSelectionMerge %53 None
+OpSwitch %52 %57 2 %54 1 %55 0 %56
+%54 = OpLabel
+OpBranch %53
+%55 = OpLabel
+OpBranch %56
+%56 = OpLabel
+OpStore %_0_ok %true
+OpBranch %53
+%57 = OpLabel
+OpBranch %53
+%53 = OpLabel
+%58 = OpLoad %bool %_0_ok
+OpSelectionMerge %60 None
+OpBranchConditional %58 %59 %60
+%59 = OpLabel
+%61 = OpLoad %int %x
+OpStore %62 %61
+%63 = OpFunctionCall %bool %switch_fallthrough_twice_bi %62
+OpBranch %60
 %60 = OpLabel
-%62 = OpLoad %int %x
-OpStore %63 %62
-%64 = OpFunctionCall %bool %switch_fallthrough_twice_bi %63
-OpBranch %61
-%61 = OpLabel
-%65 = OpPhi %bool %false %49 %64 %60
-OpSelectionMerge %70 None
-OpBranchConditional %65 %68 %69
+%64 = OpPhi %bool %false %53 %63 %59
+OpSelectionMerge %69 None
+OpBranchConditional %64 %67 %68
+%67 = OpLabel
+%70 = OpAccessChain %_ptr_Uniform_v4float %11 %int_0
+%71 = OpLoad %v4float %70
+OpStore %65 %71
+OpBranch %69
 %68 = OpLabel
-%71 = OpAccessChain %_ptr_Uniform_v4float %12 %int_0
-%72 = OpLoad %v4float %71
-OpStore %66 %72
-OpBranch %70
+%72 = OpAccessChain %_ptr_Uniform_v4float %11 %int_1
+%74 = OpLoad %v4float %72
+OpStore %65 %74
+OpBranch %69
 %69 = OpLabel
-%73 = OpAccessChain %_ptr_Uniform_v4float %12 %int_1
-%75 = OpLoad %v4float %73
-OpStore %66 %75
-OpBranch %70
-%70 = OpLabel
-%76 = OpLoad %v4float %66
-OpReturnValue %76
+%75 = OpLoad %v4float %65
+OpReturnValue %75
 OpFunctionEnd

tests/sksl/shared/SwitchWithFallthrough.glsl

@@ -2,30 +2,33 @@
 out vec4 sk_FragColor;
 uniform vec4 colorGreen;
 uniform vec4 colorRed;
-bool switch_fallthrough_bi(int value) {
-    switch (value) {
-        case 2:
-            return false;
-        case 1:
-        case 0:
-            return true;
-        default:
-            return false;
-    }
-}
 bool switch_fallthrough_twice_bi(int value) {
+    bool ok = false;
     switch (value) {
         case 0:
-            return false;
+            break;
         case 1:
         case 2:
         case 3:
-            return true;
+            ok = true;
+            break;
         default:
-            return false;
+            break;
     }
+    return ok;
 }
 vec4 main() {
     int x = int(colorGreen.y);
-    return switch_fallthrough_bi(x) && switch_fallthrough_twice_bi(x) ? colorGreen : colorRed;
+    bool _0_ok = false;
+    switch (x) {
+        case 2:
+            break;
+        case 1:
+        case 0:
+            _0_ok = true;
+            break;
+        default:
+            break;
+    }
+    return _0_ok && switch_fallthrough_twice_bi(x) ? colorGreen : colorRed;
 }

tests/sksl/shared/SwitchWithFallthrough.metal

@@ -10,33 +10,36 @@ struct Inputs {
 struct Outputs {
     float4 sk_FragColor [[color(0)]];
 };
-bool switch_fallthrough_bi(int value) {
-    switch (value) {
-        case 2:
-            return false;
-        case 1:
-        case 0:
-            return true;
-        default:
-            return false;
-    }
-}
 bool switch_fallthrough_twice_bi(int value) {
+    bool ok = false;
     switch (value) {
         case 0:
-            return false;
+            break;
         case 1:
         case 2:
         case 3:
-            return true;
+            ok = true;
+            break;
         default:
-            return false;
+            break;
     }
+    return ok;
 }
 fragment Outputs fragmentMain(Inputs _in [[stage_in]], constant Uniforms& _uniforms [[buffer(0)]], bool _frontFacing [[front_facing]], float4 _fragCoord [[position]]) {
     Outputs _out;
     (void)_out;
     int x = int(_uniforms.colorGreen.y);
-    _out.sk_FragColor = switch_fallthrough_bi(x) && switch_fallthrough_twice_bi(x) ? _uniforms.colorGreen : _uniforms.colorRed;
+    bool _0_ok = false;
+    switch (x) {
+        case 2:
+            break;
+        case 1:
+        case 0:
+            _0_ok = true;
+            break;
+        default:
+            break;
+    }
+    _out.sk_FragColor = _0_ok && switch_fallthrough_twice_bi(x) ? _uniforms.colorGreen : _uniforms.colorRed;
     return _out;
 }