commit 6b13129c30e13a40be9b64f6b950d1475d7b4966
author John Stiles <johnstiles@google.com> Wed May 12 17:12:21 2021 -0400
committer Skia Commit-Bot <skia-commit-bot@chromium.org> Thu May 13 17:22:43 2021 +0000
tree 17573137125313bd98c43d7350ba489f58a95cd5
parent e3f8030494b417904790b95b689ca25ad945df21

Add support for matrix + scalar to Metal codegen.

The Metal code generator will now detect matrix-op-scalar expressions
and splat the scalar across a matrix. This allows a scalar to be added
to, or subtracted from, a matrix. (It does not fix division because
Metal also does not natively support componentwise division on
matrices.)

Change-Id: I7d5b0c5bd35393475c524e34cad789bf4f72a103
Bug: skia:11125
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/407616
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>

src/sksl/codegen/SkSLMetalCodeGenerator.cpp

diff --git a/src/sksl/codegen/SkSLMetalCodeGenerator.cpp b/src/sksl/codegen/SkSLMetalCodeGenerator.cpp
index 87204f4..a08133e 100644
--- a/src/sksl/codegen/SkSLMetalCodeGenerator.cpp
+++ b/src/sksl/codegen/SkSLMetalCodeGenerator.cpp
@@ -1339,6 +1339,27 @@
     }
 }
 
+void MetalCodeGenerator::writeNumberAsMatrix(const Expression& expr, const Type& matrixType) {
+    SkASSERT(expr.type().isNumber());
+    SkASSERT(matrixType.isMatrix());
+
+    // Componentwise multiply the scalar against a matrix of the desired size which contains all 1s.
+    this->write("(");
+    this->writeType(matrixType);
+    this->write("(");
+
+    const char* separator = "";
+    for (int index = matrixType.slotCount(); index--;) {
+        this->write(separator);
+        this->write("1.0");
+        separator = ", ";
+    }
+
+    this->write(") * ");
+    this->writeExpression(expr, Precedence::kMultiplicative);
+    this->write(")");
+}
+
 void MetalCodeGenerator::writeBinaryExpression(const BinaryExpression& b,
                                                Precedence parentPrecedence) {
     const Expression& left = *b.left();
@@ -1372,7 +1393,14 @@
     if (leftType.isMatrix() && rightType.isMatrix() && op.kind() == Token::Kind::TK_STAREQ) {
         this->writeMatrixTimesEqualHelper(leftType, rightType, b.type());
     }
-    this->writeExpression(left, precedence);
+
+    bool needMatrixSplatOnScalar = rightType.isMatrix() && leftType.isScalar() &&
+                                   op.removeAssignment().kind() != Token::Kind::TK_STAR;
+    if (needMatrixSplatOnScalar) {
+        this->writeNumberAsMatrix(left, rightType);
+    } else {
+        this->writeExpression(left, precedence);
+    }
     if (op.kind() != Token::Kind::TK_EQ && op.isAssignment() &&
         left.kind() == Expression::Kind::kSwizzle && !left.hasSideEffects()) {
         // This doesn't compile in Metal:
@@ -1391,7 +1419,14 @@
     } else {
         this->write(String(" ") + OperatorName(op) + " ");
     }
-    this->writeExpression(right, precedence);
+
+    needMatrixSplatOnScalar = leftType.isMatrix() && rightType.isScalar() &&
+                              op.removeAssignment().kind() != Token::Kind::TK_STAR;
+    if (needMatrixSplatOnScalar) {
+        this->writeNumberAsMatrix(right, leftType);
+    } else {
+        this->writeExpression(right, precedence);
+    }
     if (needParens) {
         this->write(")");
     }