Improved skslc optimizer, particularly around vectors.

BUG=skia:

Change-Id: Idb364d9198f2ff84aad1eb68e236fb45ec1c86b7
Reviewed-on: https://skia-review.googlesource.com/8000
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Ben Wagner <benjaminwagner@google.com>

1 files changed, 23 insertions, 1 deletions

diff --git a/src/sksl/ir/SkSLPrefixExpression.h b/src/sksl/ir/SkSLPrefixExpression.h
index 4fa54ca32d..a61ff65bd6 100644
--- a/src/sksl/ir/SkSLPrefixExpression.h
+++ b/src/sksl/ir/SkSLPrefixExpression.h
@@ -22,7 +22,29 @@ struct PrefixExpression : public Expression {
     , fOperand(std::move(operand))
     , fOperator(op) {}
 
-    virtual String description() const override {
+    bool isConstant() const override {
+        return fOperator == Token::MINUS && fOperand->isConstant();
+    }
+
+    bool hasSideEffects() const override {
+        return fOperator == Token::PLUSPLUS || fOperator == Token::MINUSMINUS ||
+               fOperand->hasSideEffects();
+    }
+
+    virtual std::unique_ptr<Expression> constantPropagate(
+                                                        const IRGenerator& irGenerator,
+                                                        const DefinitionMap& definitions) override {
+        if (fOperand->fKind == Expression::kFloatLiteral_Kind) {
+            return std::unique_ptr<Expression>(new FloatLiteral(
+                                                              irGenerator.fContext,
+                                                              Position(),
+                                                              -((FloatLiteral&) *fOperand).fValue));
+
+        }
+        return nullptr;
+    }
+
+    String description() const override {
         return Token::OperatorName(fOperator) + fOperand->description();
     }