workaround for buggy macOS GLSL shader compiler

Bug: skia:
Change-Id: Ib77e11d80f93f76e65eac6119dbf2bd03523aaf9
Reviewed-on: https://skia-review.googlesource.com/117626
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>

2 files changed, 17 insertions, 23 deletions

diff --git a/src/sksl/SkSLIRGenerator.cpp b/src/sksl/SkSLIRGenerator.cpp
index 56d8e5e952..a0de551bb3 100644
--- a/src/sksl/SkSLIRGenerator.cpp
+++ b/src/sksl/SkSLIRGenerator.cpp
@@ -613,8 +613,7 @@ std::unique_ptr<Block> IRGenerator::applyInvocationIDWorkaround(std::unique_ptr<
 }
 
 std::unique_ptr<Statement> IRGenerator::getNormalizeSkPositionCode() {
-    // sk_Position = float4(sk_Position.x * rtAdjust.x + sk_Position.w * rtAdjust.y,
-    //                      sk_Position.y * rtAdjust.z + sk_Position.w * rtAdjust.w,
+    // sk_Position = float4(sk_Position.xy * rtAdjust.xz + sk_Position.ww * rtAdjust.yw,
     //                      0,
     //                      sk_Position.w);
     ASSERT(fSkPerVertex && fRTAdjust);
@@ -627,16 +626,15 @@ std::unique_ptr<Statement> IRGenerator::getNormalizeSkPositionCode() {
     #define ADJUST (fRTAdjustInterfaceBlock ? \
                     FIELD(fRTAdjustInterfaceBlock, fRTAdjustFieldIndex) : \
                     REF(fRTAdjust))
-    #define SWIZZLE(expr, field) std::unique_ptr<Expression>(new Swizzle(fContext, expr, { field }))
-    #define OP(left, op, right) std::unique_ptr<Expression>(\
-                                   new BinaryExpression(-1, left, op, right, *fContext.fFloat_Type))
+    #define SWIZZLE(expr, ...) std::unique_ptr<Expression>(new Swizzle(fContext, expr, \
+                                                                       { __VA_ARGS__ }))
+    #define OP(left, op, right) std::unique_ptr<Expression>( \
+                                   new BinaryExpression(-1, left, op, right, \
+                                                        *fContext.fFloat2_Type))
     std::vector<std::unique_ptr<Expression>> children;
-    children.push_back(OP(OP(SWIZZLE(POS, 0), Token::STAR, SWIZZLE(ADJUST, 0)),
+    children.push_back(OP(OP(SWIZZLE(POS, 0, 1), Token::STAR, SWIZZLE(ADJUST, 0, 2)),
                           Token::PLUS,
-                          OP(SWIZZLE(POS, 3), Token::STAR, SWIZZLE(ADJUST, 1))));
-    children.push_back(OP(OP(SWIZZLE(POS, 1), Token::STAR, SWIZZLE(ADJUST, 2)),
-                          Token::PLUS,
-                          OP(SWIZZLE(POS, 3), Token::STAR, SWIZZLE(ADJUST, 3))));
+                          OP(SWIZZLE(POS, 3, 3), Token::STAR, SWIZZLE(ADJUST, 1, 3))));
     children.push_back(std::unique_ptr<Expression>(new FloatLiteral(fContext, -1, 0.0)));
     children.push_back(SWIZZLE(POS, 3));
     std::unique_ptr<Expression> result = OP(POS, Token::EQ,
@@ -646,6 +644,7 @@ std::unique_ptr<Statement> IRGenerator::getNormalizeSkPositionCode() {
     return std::unique_ptr<Statement>(new ExpressionStatement(std::move(result)));
 }
 
+
 void IRGenerator::convertFunction(const ASTFunction& f) {
     const Type* returnType = this->convertType(*f.fReturnType);
     if (!returnType) {
diff --git a/tests/SkSLGLSLTest.cpp b/tests/SkSLGLSLTest.cpp
index 0b9ed35006..fe30ef49fd 100644
--- a/tests/SkSLGLSLTest.cpp
+++ b/tests/SkSLGLSLTest.cpp
@@ -1136,9 +1136,8 @@ DEF_TEST(SkSLFragCoord, r) {
          "in vec4 pos;\n"
          "void main() {\n"
          "    sk_FragCoord_Workaround = (gl_Position = pos);\n"
-         "    gl_Position = vec4(gl_Position.x * sk_RTAdjust.x + gl_Position.w * sk_RTAdjust.y, "
-              "gl_Position.y * sk_RTAdjust.z + gl_Position.w * sk_RTAdjust.w, 0.0, "
-              "gl_Position.w);\n"
+         "    gl_Position = vec4(gl_Position.xy * sk_RTAdjust.xz + gl_Position.ww * sk_RTAdjust.yw,"
+                                " 0.0, gl_Position.w);\n"
          "}\n",
          SkSL::Program::kVertex_Kind);
 
@@ -1818,10 +1817,8 @@ DEF_TEST(SkSLNormalization, r) {
          "uniform vec4 sk_RTAdjust;\n"
          "void main() {\n"
          "    gl_Position = vec4(1.0);\n"
-         "    gl_Position = vec4(gl_Position.x * sk_RTAdjust.x + gl_Position.w * sk_RTAdjust.y, "
-                                "gl_Position.y * sk_RTAdjust.z + gl_Position.w * sk_RTAdjust.w, "
-                                "0.0, "
-                                "gl_Position.w);\n"
+         "    gl_Position = vec4(gl_Position.xy * sk_RTAdjust.xz + gl_Position.ww * "
+                                "sk_RTAdjust.yw, 0.0, gl_Position.w);\n"
          "}\n",
          SkSL::Program::kVertex_Kind);
     test(r,
@@ -1845,16 +1842,14 @@ DEF_TEST(SkSLNormalization, r) {
          "void main() {\n"
          "    gl_Position = gl_in[0].gl_Position + vec4(-0.5, 0.0, 0.0, float(gl_InvocationID));\n"
          "    {\n"
-         "        gl_Position = vec4(gl_Position.x * sk_RTAdjust.x + gl_Position.w * "
-                               "sk_RTAdjust.y, gl_Position.y * sk_RTAdjust.z + gl_Position.w * "
-                               "sk_RTAdjust.w, 0.0, gl_Position.w);\n"
+         "        gl_Position = vec4(gl_Position.xy * sk_RTAdjust.xz + gl_Position.ww * "
+                                    "sk_RTAdjust.yw, 0.0, gl_Position.w);\n"
          "        EmitVertex();\n"
          "    }\n"
          "    gl_Position = gl_in[0].gl_Position + vec4(0.5, 0.0, 0.0, float(gl_InvocationID));\n"
          "    {\n"
-         "        gl_Position = vec4(gl_Position.x * sk_RTAdjust.x + gl_Position.w * "
-                               "sk_RTAdjust.y, gl_Position.y * sk_RTAdjust.z + gl_Position.w * "
-                               "sk_RTAdjust.w, 0.0, gl_Position.w);\n"
+         "        gl_Position = vec4(gl_Position.xy * sk_RTAdjust.xz + gl_Position.ww * "
+                                    "sk_RTAdjust.yw, 0.0, gl_Position.w);\n"
          "        EmitVertex();\n"
          "    }\n"
          "    EndPrimitive();\n"