sksl optimizer fixes

The main issue was a use-after-free due to removing (and thus destroying)
the binary expression prior to re-adding part of it. Also cleaned up the
way dead assignments are handled and added the test that originally
identified these problems.

Bug: skia:
Change-Id: Icda93d69a66c4e57850ecdc88fc4a4f634e1aac2
Reviewed-on: https://skia-review.googlesource.com/15383
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Ben Wagner <benjaminwagner@google.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/tests/SkSLGLSLTest.cpp b/tests/SkSLGLSLTest.cpp
index b945211eca..32fd668dda 100644
--- a/tests/SkSLGLSLTest.cpp
+++ b/tests/SkSLGLSLTest.cpp
@@ -1213,4 +1213,21 @@ DEF_TEST(SkSLUnusedVars, r) {
          "}\n");
 }
 
+DEF_TEST(SkSLMultipleAssignments, r) {
+    test(r,
+         "void main() {"
+         "float x;"
+         "float y;"
+         "int z;"
+         "x = y = z = 1;"
+         "sk_FragColor = vec4(z);"
+         "}",
+         *SkSL::ShaderCapsFactory::Default(),
+         "#version 400\n"
+         "out vec4 sk_FragColor;\n"
+         "void main() {\n"
+         "    sk_FragColor = vec4(1.0);\n"
+         "}\n");
+}
+
 #endif