Test that the inliner uses a temp var for return statements.

We have a handful of tests that demonstrate this behavior indirectly,
but lacked a focused test.

Change-Id: I895cc4e3bebf30721ed649244e42bf170cc6ec06
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/346497
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>

gn/sksl_tests.gni

@@ -391,6 +391,9 @@ sksl_inliner_tests = [
   "$_tests/sksl/inliner/IfWithReturnsCanBeInlined.sksl",
   "$_tests/sksl/inliner/InlineKeywordOverridesThreshold.sksl",
   "$_tests/sksl/inliner/InlineThreshold.sksl",
+  "$_tests/sksl/inliner/InlinerUsesTempVarForMultipleReturns.sksl",
+  "$_tests/sksl/inliner/InlinerUsesTempVarForReturnsInsideBlock.sksl",
+  "$_tests/sksl/inliner/InlinerUsesTempVarForReturnsInsideBlockWithVar.sksl",
   "$_tests/sksl/inliner/InlineWithInoutArgument.sksl",
   "$_tests/sksl/inliner/InlineWithModifiedArgument.sksl",
   "$_tests/sksl/inliner/InlineWithNestedBigCalls.sksl",

tests/sksl/inliner/InlinerUsesTempVarForMultipleReturns.sksl

@@ -0,0 +1,15 @@
+/*#pragma settings Default*/
+
+uniform half4 color;
+
+inline half4 MakeTempVar(half4 c) {
+    if (c.x < c.y) {
+        return c.xxxx;
+    } else {
+        return c.yyyy;
+    }
+}
+
+void main() {
+    sk_FragColor = MakeTempVar(color);
+}

tests/sksl/inliner/InlinerUsesTempVarForReturnsInsideBlock.sksl

@@ -0,0 +1,13 @@
+/*#pragma settings Default*/
+
+uniform half4 color;
+
+inline half4 MakeTempVar(half4 c) {
+    {
+        return c.xxxx;
+    }
+}
+
+void main() {
+    sk_FragColor = MakeTempVar(color);
+}

tests/sksl/inliner/InlinerUsesTempVarForReturnsInsideBlockWithVar.sksl

@@ -0,0 +1,14 @@
+/*#pragma settings Default*/
+
+uniform half4 color;
+
+inline half4 MakeTempVar(half4 c) {
+    {
+        half4 d = c * 0.75;
+        return d.xxxx;
+    }
+}
+
+void main() {
+    sk_FragColor = MakeTempVar(color);
+}

tests/sksl/inliner/golden/InlinerUsesTempVarForMultipleReturns.glsl

@@ -0,0 +1,13 @@
+#version 400
+out vec4 sk_FragColor;
+uniform vec4 color;
+void main() {
+    vec4 _0_MakeTempVar;
+    if (color.x < color.y) {
+        _0_MakeTempVar = color.xxxx;
+    } else {
+        _0_MakeTempVar = color.yyyy;
+    }
+    sk_FragColor = _0_MakeTempVar;
+
+}

tests/sksl/inliner/golden/InlinerUsesTempVarForReturnsInsideBlock.glsl

@@ -0,0 +1,11 @@
+#version 400
+out vec4 sk_FragColor;
+uniform vec4 color;
+void main() {
+    vec4 _0_MakeTempVar;
+    {
+        _0_MakeTempVar = color.xxxx;
+    }
+    sk_FragColor = _0_MakeTempVar;
+
+}

tests/sksl/inliner/golden/InlinerUsesTempVarForReturnsInsideBlockWithVar.glsl

@@ -0,0 +1,12 @@
+#version 400
+out vec4 sk_FragColor;
+uniform vec4 color;
+void main() {
+    vec4 _0_MakeTempVar;
+    {
+        vec4 _1_d = color * 0.75;
+        _0_MakeTempVar = _1_d.xxxx;
+    }
+    sk_FragColor = _0_MakeTempVar;
+
+}