Revert "Rename gl_SampleMask to sk_SampleMask"

This reverts commit 23716d42f7.

Reason for revert: red bots and GMs

Original change's description:
> Rename gl_SampleMask to sk_SampleMask
> 
> Change-Id: I3924c6f76edf310a984e4fd89478b00eeec69722
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/249931
> Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
> Commit-Queue: Chris Dalton <csmartdalton@google.com>

TBR=egdaniel@google.com,csmartdalton@google.com,ethannicholas@google.com

Change-Id: I74848e95972cf2c41cc28887e26214136ce79e08
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/250180
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>

src/gpu/glsl/GrGLSLFragmentShaderBuilder.cpp

@@ -105,15 +105,15 @@ void GrGLSLFragmentShaderBuilder::maskOffMultisampleCoverage(
     if (!fHasModifiedSampleMask) {
         fHasModifiedSampleMask = true;
         if (ScopeFlags::kTopLevel != scopeFlags) {
-            this->codePrependf("sk_SampleMask[0] = ~0;");
+            this->codePrependf("gl_SampleMask[0] = ~0;");
         }
         if (!(ScopeFlags::kInsideLoop & scopeFlags)) {
-            this->codeAppendf("sk_SampleMask[0] = (%s);", mask);
+            this->codeAppendf("gl_SampleMask[0] = (%s);", mask);
             return;
         }
     }
 
-    this->codeAppendf("sk_SampleMask[0] &= (%s);", mask);
+    this->codeAppendf("gl_SampleMask[0] &= (%s);", mask);
 }
 
 void GrGLSLFragmentShaderBuilder::applyFnToMultisampleMask(

src/sksl/SkSLCompiler.h

@@ -36,7 +36,6 @@
 #define SK_HEIGHT_BUILTIN              10012
 #define SK_FRAGCOORD_BUILTIN              15
 #define SK_CLOCKWISE_BUILTIN              17
-#define SK_SAMPLEMASK_BUILTIN             20
 #define SK_VERTEXID_BUILTIN               42
 #define SK_INSTANCEID_BUILTIN             43
 #define SK_CLIPDISTANCE_BUILTIN            3

src/sksl/SkSLGLSLCodeGenerator.cpp

@@ -796,10 +796,6 @@ void GLSLCodeGenerator::writeVariableReference(const VariableReference& ref) {
         case SK_CLOCKWISE_BUILTIN:
             this->write(fProgram.fSettings.fFlipY ? "(!gl_FrontFacing)" : "gl_FrontFacing");
             break;
-        case SK_SAMPLEMASK_BUILTIN:
-            SkASSERT(fProgram.fSettings.fCaps->sampleVariablesSupport());
-            this->write("gl_SampleMask");
-            break;
         case SK_VERTEXID_BUILTIN:
             this->write("gl_VertexID");
             break;

src/sksl/SkSLUtil.h

@@ -377,12 +377,6 @@ public:
         result->fRemovePowWithConstantExponent = true;
         return result;
     }
-
-    static sk_sp<GrShaderCaps> SampleMaskSupport() {
-        sk_sp<GrShaderCaps> result = Default();
-        result->fSampleVariablesSupport = true;
-        return result;
-    }
 };
 #endif
 

src/sksl/sksl_fp.inc

@@ -4,7 +4,6 @@ STRINGIFY(
 
 layout(builtin=15) in float4 sk_FragCoord;
 layout(builtin=3) float sk_ClipDistance[1];
-layout(builtin=20) out int sk_SampleMask[1];
 
 // 9999 is a temporary value that causes us to ignore these declarations beyond
 // adding them to the symbol table. This works fine in GLSL (where they do not
@@ -13,6 +12,8 @@ layout(builtin=20) out int sk_SampleMask[1];
 layout(builtin=9999) float4 gl_LastFragData[1];
 layout(builtin=9999) half4 gl_LastFragColor;
 layout(builtin=9999) half4 gl_LastFragColorARM;
+layout(builtin=9999) int gl_SampleMaskIn[1];
+layout(builtin=9999) out int gl_SampleMask[1];
 layout(builtin=9999) half4 gl_SecondaryFragColorEXT;
 
 layout(builtin=10003) half4 sk_InColor;

src/sksl/sksl_frag.inc

@@ -6,12 +6,13 @@ STRINGIFY(
 layout(builtin=15) in float4 sk_FragCoord;
 layout(builtin=17) in bool sk_Clockwise;  // Similar to gl_FrontFacing, but defined in device space.
 layout(builtin=3) float sk_ClipDistance[1];
-layout(builtin=20) out int sk_SampleMask[1];
 
 // 9999 is a temporary value that causes us to ignore these declarations beyond
 // adding them to the symbol table. This works fine in GLSL (where they do not
 // require any further handling) but will fail in SPIR-V. We'll have a better
 // solution for this soon.
+layout(builtin=9999) int gl_SampleMaskIn[1];
+layout(builtin=9999) out int gl_SampleMask[1];
 layout(builtin=9999) out half4 gl_SecondaryFragColorEXT;
 
 layout(location=0,index=0,builtin=10001) out half4 sk_FragColor;

tests/SkSLGLSLTest.cpp

@@ -1316,16 +1316,6 @@ DEF_TEST(SkSLClockwise, r) {
          "}\n");
 }
 
-DEF_TEST(SkSLSampleMask, r) {
-    test(r,
-         "void main() { sk_SampleMask[0] |= 8; }",
-         *SkSL::ShaderCapsFactory::SampleMaskSupport(),
-         "#version 400\n"
-         "void main() {\n"
-         "    gl_SampleMask[0] |= 8;\n"
-         "}\n");
-}
-
 DEF_TEST(SkSLVertexID, r) {
     test(r,
          "out int id; void main() { id = sk_VertexID; }",