commit 4f1593eaeea0ae3a3997e55c97fc4a9c934bebd0
author John Stiles <johnstiles@google.com> Wed Sep 15 12:35:25 2021 -0400
committer SkCQ <skcq-be@skia-corp.google.com.iam.gserviceaccount.com> Wed Sep 15 17:32:45 2021 +0000
tree fa3eaa73a76cf90aa5192b748930fcf2cacc3941
parent faf8d57fba1882cb210a353b0b6684749f4403d7

Use swizzles in Metal matrix helper functions.

Not a big deal necessarily, but considering using this logic in GLSL as
well, and I'm less confident that your average GLSL ES driver will
optimize away the separate array loads.

Change-Id: I6a9f0d18c0fac138f64ad6426670f615e17f3492
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/449099
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>

src/sksl/codegen/SkSLMetalCodeGenerator.cpp

diff --git a/src/sksl/codegen/SkSLMetalCodeGenerator.cpp b/src/sksl/codegen/SkSLMetalCodeGenerator.cpp
index bb34f30..c0cd482 100644
--- a/src/sksl/codegen/SkSLMetalCodeGenerator.cpp
+++ b/src/sksl/codegen/SkSLMetalCodeGenerator.cpp
@@ -947,13 +947,14 @@
     int argPosition = 0;
     auto args = ctor.argumentSpan();
 
+    static constexpr char kSwizzle[] = "xyzw";
     const char* separator = "";
     for (int c = 0; c < columns; ++c) {
         fExtraFunctions.printf("%s%s%d(", separator, matrixType.c_str(), rows);
         separator = "), ";
 
         const char* columnSeparator = "";
-        for (int r = 0; r < rows; ++r) {
+        for (int r = 0; r < rows;) {
             fExtraFunctions.writeText(columnSeparator);
             columnSeparator = ", ";
 
@@ -962,16 +963,26 @@
                 switch (argType.typeKind()) {
                     case Type::TypeKind::kScalar: {
                         fExtraFunctions.printf("x%zu", argIndex);
+                        ++r;
+                        ++argPosition;
                         break;
                     }
                     case Type::TypeKind::kVector: {
-                        fExtraFunctions.printf("x%zu[%d]", argIndex, argPosition);
+                        fExtraFunctions.printf("x%zu.", argIndex);
+                        do {
+                            fExtraFunctions.write8(kSwizzle[argPosition]);
+                            ++r;
+                            ++argPosition;
+                        } while (r < rows && argPosition < argType.columns());
                         break;
                     }
                     case Type::TypeKind::kMatrix: {
-                        fExtraFunctions.printf("x%zu[%d][%d]", argIndex,
-                                               argPosition / argType.rows(),
-                                               argPosition % argType.rows());
+                        fExtraFunctions.printf("x%zu[%d].", argIndex, argPosition / argType.rows());
+                        do {
+                            fExtraFunctions.write8(kSwizzle[argPosition]);
+                            ++r;
+                            ++argPosition;
+                        } while (r < rows && (argPosition % argType.rows()) != 0);
                         break;
                     }
                     default: {
@@ -981,7 +992,6 @@
                     }
                 }
 
-                ++argPosition;
                 if (argPosition >= argType.columns() * argType.rows()) {
                     ++argIndex;
                     argPosition = 0;