added constant folding & branch elimination to skslc

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2489673002

Committed: https://skia.googlesource.com/skia/+/6136310ee8f43247548bcefcaeca6d43023c10aa
Review-Url: https://codereview.chromium.org/2489673002

2 files changed, 117 insertions, 4 deletions

diff --git a/tests/SkSLErrorTest.cpp b/tests/SkSLErrorTest.cpp
index 9e89b71473..fc20fa2e6d 100644
--- a/tests/SkSLErrorTest.cpp
+++ b/tests/SkSLErrorTest.cpp
@@ -352,3 +352,19 @@ DEF_TEST(SkSLContinueOutsideLoop, r) {
                  "void foo() { for(;;); continue; }",
                  "error: 1: continue statement must be inside a loop\n1 error\n");
 }
+
+DEF_TEST(SkSLStaticIfError, r) {
+    // ensure eliminated branch of static if / ternary is still checked for errors
+    test_failure(r,
+                 "void foo() { if (true); else x = 5; }",
+                 "error: 1: unknown identifier 'x'\n1 error\n");
+    test_failure(r,
+                 "void foo() { if (false) x = 5; }",
+                 "error: 1: unknown identifier 'x'\n1 error\n");
+    test_failure(r,
+                 "void foo() { true ? 5 : x; }",
+                 "error: 1: unknown identifier 'x'\n1 error\n");
+    test_failure(r,
+                 "void foo() { false ? x : 5; }",
+                 "error: 1: unknown identifier 'x'\n1 error\n");
+}
diff --git a/tests/SkSLGLSLTest.cpp b/tests/SkSLGLSLTest.cpp
index 610ff2b5ab..38fce87e87 100644
--- a/tests/SkSLGLSLTest.cpp
+++ b/tests/SkSLGLSLTest.cpp
@@ -43,7 +43,7 @@ DEF_TEST(SkSLHelloWorld, r) {
 DEF_TEST(SkSLControl, r) {
     test(r,
          "void main() {"
-         "if (1 + 2 + 3 > 5) { sk_FragColor = vec4(0.75); } else { discard; }"
+         "if (sqrt(2) > 5) { sk_FragColor = vec4(0.75); } else { discard; }"
          "int i = 0;"
          "while (i < 10) sk_FragColor *= 0.5;"
          "do { sk_FragColor += 0.01; } while (sk_FragColor.x < 0.7);"
@@ -55,7 +55,7 @@ DEF_TEST(SkSLControl, r) {
          default_caps(),
          "#version 400\n"
          "void main() {\n"
-         "    if ((1 + 2) + 3 > 5) {\n"
+         "    if (sqrt(2.0) > 5.0) {\n"
          "        gl_FragColor = vec4(0.75);\n"
          "    } else {\n"
          "        discard;\n"
@@ -104,7 +104,7 @@ DEF_TEST(SkSLOperators, r) {
          "x = x + y * z * x * (y - z);"
          "y = x / y / z;"
          "z = (z / 2 % 3 << 4) >> 2 << 1;"
-         "bool b = (x > 4) == x < 2 || 2 >= 5 && y <= z && 12 != 11;"
+         "bool b = (x > 4) == x < 2 || 2 >= sqrt(2) && y <= z;"
          "x += 12;"
          "x -= 12;"
          "x *= y /= z = 10;"
@@ -126,7 +126,7 @@ DEF_TEST(SkSLOperators, r) {
          "    x = x + ((y * float(z)) * x) * (y - float(z));\n"
          "    y = (x / y) / float(z);\n"
          "    z = (((z / 2) % 3 << 4) >> 2) << 1;\n"
-         "    bool b = x > 4.0 == x < 2.0 || (2 >= 5 && y <= float(z)) && 12 != 11;\n"
+         "    bool b = x > 4.0 == x < 2.0 || 2.0 >= sqrt(2.0) && y <= float(z);\n"
          "    x += 12.0;\n"
          "    x -= 12.0;\n"
          "    x *= (y /= float(z = 10));\n"
@@ -430,3 +430,100 @@ DEF_TEST(SkSLDerivatives, r) {
          "    float x = dFdx(1.0);\n"
          "}\n");
 }
+
+DEF_TEST(SkSLConstantFolding, r) {
+    test(r,
+         "void main() {"
+         "float f_add = 32 + 2;"
+         "float f_sub = 32 - 2;"
+         "float f_mul = 32 * 2;"
+         "float f_div = 32 / 2;"
+         "float mixed = (12 > 2.0) ? (10 * 2 / 5 + 18 - 3) : 0;"
+         "int i_add = 32 + 2;"
+         "int i_sub = 32 - 2;"
+         "int i_mul = 32 * 2;"
+         "int i_div = 32 / 2;"
+         "int i_or = 12 | 6;"
+         "int i_and = 254 & 7;"
+         "int i_xor = 2 ^ 7;"
+         "int i_shl = 1 << 4;"
+         "int i_shr = 128 >> 2;"
+         "bool gt_it = 6 > 5;"
+         "bool gt_if = 6 > 6;"
+         "bool gt_ft = 6.0 > 5.0;"
+         "bool gt_ff = 6.0 > 6.0;"
+         "bool gte_it = 6 >= 6;"
+         "bool gte_if = 6 >= 7;"
+         "bool gte_ft = 6.0 >= 6.0;"
+         "bool gte_ff = 6.0 >= 7.0;"
+         "bool lte_it = 6 <= 6;"
+         "bool lte_if = 6 <= 5;"
+         "bool lte_ft = 6.0 <= 6.0;"
+         "bool lte_ff = 6.0 <= 5.0;"
+         "bool or_t = 1 == 1 || 2 == 8;"
+         "bool or_f = 1 > 1 || 2 == 8;"
+         "bool and_t = 1 == 1 && 2 <= 8;"
+         "bool and_f = 1 == 2 && 2 == 8;"
+         "bool xor_t = 1 == 1 ^^ 1 != 1;"
+         "bool xor_f = 1 == 1 ^^ 1 == 1;"
+         "int ternary = 10 > 5 ? 10 : 5;"
+         "}",
+         default_caps(),
+         "#version 400\n"
+         "void main() {\n"
+         "    float f_add = 34.0;\n"
+         "    float f_sub = 30.0;\n"
+         "    float f_mul = 64.0;\n"
+         "    float f_div = 16.0;\n"
+         "    float mixed = 19.0;\n"
+         "    int i_add = 34;\n"
+         "    int i_sub = 30;\n"
+         "    int i_mul = 64;\n"
+         "    int i_div = 16;\n"
+         "    int i_or = 14;\n"
+         "    int i_and = 6;\n"
+         "    int i_xor = 5;\n"
+         "    int i_shl = 16;\n"
+         "    int i_shr = 32;\n"
+         "    bool gt_it = true;\n"
+         "    bool gt_if = false;\n"
+         "    bool gt_ft = true;\n"
+         "    bool gt_ff = false;\n"
+         "    bool gte_it = true;\n"
+         "    bool gte_if = false;\n"
+         "    bool gte_ft = true;\n"
+         "    bool gte_ff = false;\n"
+         "    bool lte_it = true;\n"
+         "    bool lte_if = false;\n"
+         "    bool lte_ft = true;\n"
+         "    bool lte_ff = false;\n"
+         "    bool or_t = true;\n"
+         "    bool or_f = false;\n"
+         "    bool and_t = true;\n"
+         "    bool and_f = false;\n"
+         "    bool xor_t = true;\n"
+         "    bool xor_f = false;\n"
+         "    int ternary = 10;\n"
+         "}\n");
+}
+
+DEF_TEST(SkSLStaticIf, r) {
+    test(r,
+         "void main() {"
+         "int x;"
+         "if (true) x = 1;"
+         "if (2 > 1) x = 2; else x = 3;"
+         "if (1 > 2) x = 4; else x = 5;"
+         "if (false) x = 6;"
+         "}",
+         default_caps(),
+         "#version 400\n"
+         "void main() {\n"
+         "    int x;\n"
+         "    x = 1;\n"
+         "    x = 2;\n"
+         "    x = 5;\n"
+         "    {\n"
+         "    }\n"
+         "}\n");
+}