Avoid undefined behavior and enable asserts in ClampTest.

The old code here wasn't being careful to avoid int32_t overflow in slow_check.  Fix that.

R_ASSERT hasn't been doing anything for a while.  As a result, there are a couple bugs in SkClampRange, marked as such and commented out.  The asserts also weren't quite passing, so I fixed them up (allowing 0xFFFF to be considered either as part of the ramp or part of V1.)

BUG=skia:2481
R=reed@google.com, mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/260523004

git-svn-id: http://skia.googlecode.com/svn/trunk@14479 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 34 insertions, 47 deletions

diff --git a/tests/ClampRangeTest.cpp b/tests/ClampRangeTest.cpp
index dee777c4ad..bf7c95fa57 100644
--- a/tests/ClampRangeTest.cpp
+++ b/tests/ClampRangeTest.cpp
@@ -10,71 +10,54 @@
 #include "gradients/SkClampRange.h"
 
 static skiatest::Reporter* gReporter;
-
-static void debug_me() {
-    if (NULL == gReporter) {
-        SkDebugf("dsfdssd\n");
-    }
+#define R_ASSERT(cond) if (!(cond)) {      \
+    SkDebugf("%d: %s\n", __LINE__, #cond); \
+    REPORTER_ASSERT(gReporter, cond);      \
 }
 
-#ifdef USE_REPORTER
-
-#define R_ASSERT(cond)                  \
-    do { if (!(cond)) {                 \
-    debug_me();                         \
-    REPORTER_ASSERT(gReporter, cond);   \
-    }} while (0)
-
-#else
-#define R_ASSERT(cond)                  \
-    do { if (!(cond)) {                 \
-    debug_me();                         \
-    }} while (0)
-#endif
-
-static int classify_value(SkFixed fx, int v0, int v1) {
-    if (fx <= 0) {
-        return v0;
-    }
-    if (fx >= 0xFFFF) {
-        return v1;
+// Arbitrary sentinel values outside [0, 0xFFFF].
+static const int kV0 = -42, kV1 = -53, kRamp = -64;
+
+static void check_value(int64_t bigfx, int expected) {
+    if (bigfx < 0) {
+        R_ASSERT(expected == kV0);
+    } else if (bigfx > 0xFFFF) {
+        R_ASSERT(expected == kV1);
+    } else if (bigfx == 0xFFFF) {
+        // Either one is fine (and we do see both).
+        R_ASSERT(expected == kV1 || expected == kRamp);
+    } else {
+        R_ASSERT(expected == kRamp);
     }
-    R_ASSERT(false);
-    return 0;
 }
 
-#define V0  -42
-#define V1  1024
-
 static void slow_check(const SkClampRange& range,
-                       SkFixed fx, SkFixed dx, int count) {
+                       const SkFixed fx, SkFixed dx, int count) {
     SkASSERT(range.fCount0 + range.fCount1 + range.fCount2 == count);
 
+    // If dx is large, fx will overflow if updated naively.  So we use more bits.
+    int64_t bigfx = fx;
+
     for (int i = 0; i < range.fCount0; i++) {
-        int v = classify_value(fx, V0, V1);
-        R_ASSERT(v == range.fV0);
-        fx += dx;
-    }
-    if (range.fCount1 > 0 && fx != range.fFx1) {
-//        SkDebugf("%x %x\n", fx, range.fFx1);
-        R_ASSERT(false); // bad fFx1
-        return;
+        check_value(bigfx, range.fV0);
+        bigfx += dx;
     }
+
     for (int i = 0; i < range.fCount1; i++) {
-        R_ASSERT(fx >= 0 && fx <= 0xFFFF);
-        fx += dx;
+        check_value(bigfx, kRamp);
+        bigfx += dx;
     }
+
     for (int i = 0; i < range.fCount2; i++) {
-        int v = classify_value(fx, V0, V1);
-        R_ASSERT(v == range.fV1);
-        fx += dx;
+        check_value(bigfx, range.fV1);
+        bigfx += dx;
     }
 }
 
 
 static void test_range(SkFixed fx, SkFixed dx, int count) {
     SkClampRange range;
-    range.init(fx, dx, count, V0, V1);
+    range.init(fx, dx, count, kV0, kV1);
     slow_check(range, fx, dx, count);
 }
 
@@ -96,7 +79,8 @@ DEF_TEST(ClampRange, reporter) {
     test_range(ff(1),  ff(16384),  100);
     test_range(ff(-1), ff(-16384), 100);
     test_range(ff(1)/2, ff(16384), 100);
-    test_range(ff(1)/2, ff(-16384), 100);
+    // TODO(reed): skia:2481, fix whatever bug this is, then uncomment
+    //test_range(ff(1)/2, ff(-16384), 100);
 
     SkRandom rand;
 
@@ -109,6 +93,8 @@ DEF_TEST(ClampRange, reporter) {
         test_range(fx, dx, count);
     }
 
+    // TODO(reed): skia:2481, fix whatever bug this is, then uncomment
+    /*
     // test overflow cases
     for (int i = 0; i < 100000; i++) {
         SkFixed fx = rand.nextS();
@@ -116,4 +102,5 @@ DEF_TEST(ClampRange, reporter) {
         int count = rand.nextU() % 1000 + 1;
         test_range(fx, dx, count);
     }
+    */
 }