Revert of Make the glyph array entries inline. (patchset #10 id:170001 of https://codereview.chromium.org/885903002/)

Reason for revert:
I suspect this is causing the off-by-one character issues that show up in gold.skia.org as of now. All the errors I've seen are on a Win7 bot. Example:

good:
https://gold.skia.org/img/images/35396bb0d299b81c0031dc0632a019d4.png

bad:
https://gold.skia.org/img/images/484e511f9e696d95031cd25aeae59da0.png

Original issue's description:
> Make the glyph array entries inline.
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/4c08f16b252a55e438a61f26e5581394ed177da1

TBR=mtklein@google.com,reed@google.com,herb@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/897463004

3 files changed, 133 insertions, 135 deletions

diff --git a/src/core/SkGlyph.h b/src/core/SkGlyph.h
index 4f9c5bf4cc..9abefa84c7 100644
--- a/src/core/SkGlyph.h
+++ b/src/core/SkGlyph.h
@@ -104,10 +104,8 @@ struct SkGlyph {
         kSubShiftY = 0
     };
 
-    // The code is increased by one in MakeID. Adjust back. This allows the zero
-    // id to be the invalid id.
     static unsigned ID2Code(uint32_t id) {
-        return (id & kCodeMask) - 1;
+        return id & kCodeMask;
     }
 
     static unsigned ID2SubX(uint32_t id) {
@@ -127,21 +125,17 @@ struct SkGlyph {
         return sub << (16 - kSubBits);
     }
 
-    // This and the MakeID below must not return an id of zero. Zero is used as
-    // the invalid id.
     static uint32_t MakeID(unsigned code) {
-        SkASSERT(code + 1 <= kCodeMask);
-        return code + 1;
+        return code;
     }
 
-    // See comment for MakeID above.
     static uint32_t MakeID(unsigned code, SkFixed x, SkFixed y) {
-        SkASSERT(code + 1 <= kCodeMask);
+        SkASSERT(code <= kCodeMask);
         x = FixedToSub(x);
         y = FixedToSub(y);
         return (x << (kSubShift + kSubShiftX)) |
                (y << (kSubShift + kSubShiftY)) |
-               (code + 1);
+               code;
     }
 
     void toMask(SkMask* mask) const;
diff --git a/src/core/SkGlyphCache.cpp b/src/core/SkGlyphCache.cpp
index 4a82836585..57c54bfc1e 100755
--- a/src/core/SkGlyphCache.cpp
+++ b/src/core/SkGlyphCache.cpp
@@ -66,14 +66,10 @@ SkGlyphCache::SkGlyphCache(SkTypeface* typeface, const SkDescriptor* desc, SkSca
 
     fDesc = desc->copy();
     fScalerContext->getFontMetrics(&fFontMetrics);
-            
-    // Create the sentinel SkGlyph.
-    SkGlyph* sentinel = fGlyphArray.insert(kSentinelGlyphID);
-    sentinel->init(0);
-            
-    // Initialize all index to zero which points to the sentinel SkGlyph.
-    memset(fGlyphHash, 0x00, sizeof(fGlyphHash));
 
+    // init to 0 so that all of the pointers will be null
+    memset(fGlyphHash, 0, sizeof(fGlyphHash));
+            
     fMemoryUsed = sizeof(*this);
 
     fGlyphArray.setReserve(kMinGlyphCount);
@@ -110,10 +106,10 @@ SkGlyphCache::~SkGlyphCache() {
 
     }
 #endif
-    SkGlyph*   gptr = fGlyphArray.begin();
-    SkGlyph*   stop = fGlyphArray.end();
+    SkGlyph**   gptr = fGlyphArray.begin();
+    SkGlyph**   stop = fGlyphArray.end();
     while (gptr < stop) {
-        SkPath* path = gptr->fPath;
+        SkPath* path = (*gptr)->fPath;
         if (path) {
             SkDELETE(path);
         }
@@ -126,31 +122,15 @@ SkGlyphCache::~SkGlyphCache() {
 
 SkGlyphCache::CharGlyphRec* SkGlyphCache::getCharGlyphRec(uint32_t id) {
     if (NULL == fCharToGlyphHash.get()) {
-        // Allocate the array.
         fCharToGlyphHash.reset(kHashCount);
-        // Initialize entries of fCharToGlyphHash to index the sentinel glyph.
-        memset(fCharToGlyphHash.get(), 0x00,
+        // init with 0xFF so that the charCode field will be -1, which is invalid
+        memset(fCharToGlyphHash.get(), 0xFF,
                sizeof(CharGlyphRec) * kHashCount);
     }
     
     return &fCharToGlyphHash[ID2HashIndex(id)];
 }
 
-void SkGlyphCache::adjustCaches(int insertion_index) {
-    for (int i = 0; i < kHashCount; ++i) {
-        if (fGlyphHash[i] >= SkToU16(insertion_index)) {
-            fGlyphHash[i] += 1;
-        }
-    }
-    if (fCharToGlyphHash.get() != NULL) {
-        for (int i = 0; i < kHashCount; ++i) {
-            if (fCharToGlyphHash[i].fGlyphIndex >= SkToU16(insertion_index)) {
-                fCharToGlyphHash[i].fGlyphIndex += 1;
-            }
-        }
-    }
-}
-
 ///////////////////////////////////////////////////////////////////////////////
 
 #ifdef SK_DEBUG
@@ -165,7 +145,7 @@ uint16_t SkGlyphCache::unicharToGlyph(SkUnichar charCode) {
     const CharGlyphRec& rec = *this->getCharGlyphRec(id);
 
     if (rec.fID == id) {
-        return fGlyphArray[rec.fGlyphIndex].getGlyphID();
+        return rec.fGlyph->getGlyphID();
     } else {
         return fScalerContext->charToGlyphID(charCode);
     }
@@ -183,118 +163,159 @@ unsigned SkGlyphCache::getGlyphCount() {
 
 const SkGlyph& SkGlyphCache::getUnicharAdvance(SkUnichar charCode) {
     VALIDATE();
-    return *this->lookupByChar(charCode, kJustAdvance_MetricsType);
+    uint32_t id = SkGlyph::MakeID(charCode);
+    CharGlyphRec* rec = this->getCharGlyphRec(id);
+
+    if (rec->fID != id) {
+        // this ID is based on the UniChar
+        rec->fID = id;
+        // this ID is based on the glyph index
+        id = SkGlyph::MakeID(fScalerContext->charToGlyphID(charCode));
+        rec->fGlyph = this->lookupMetrics(id, kJustAdvance_MetricsType);
+    }
+    return *rec->fGlyph;
 }
 
 const SkGlyph& SkGlyphCache::getGlyphIDAdvance(uint16_t glyphID) {
     VALIDATE();
     uint32_t id = SkGlyph::MakeID(glyphID);
-    return *this->lookupByChar(id, kJustAdvance_MetricsType);
+    unsigned index = ID2HashIndex(id);
+    SkGlyph* glyph = fGlyphHash[index];
 
+    if (NULL == glyph || glyph->fID != id) {
+        glyph = this->lookupMetrics(glyphID, kJustAdvance_MetricsType);
+        fGlyphHash[index] = glyph;
+    }
+    return *glyph;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 const SkGlyph& SkGlyphCache::getUnicharMetrics(SkUnichar charCode) {
     VALIDATE();
-    return *this->lookupByChar(charCode, kFull_MetricsType);
+    uint32_t id = SkGlyph::MakeID(charCode);
+    CharGlyphRec* rec = this->getCharGlyphRec(id);
+
+    if (rec->fID != id) {
+        RecordHashCollisionIf(rec->fGlyph != NULL);
+        // this ID is based on the UniChar
+        rec->fID = id;
+        // this ID is based on the glyph index
+        id = SkGlyph::MakeID(fScalerContext->charToGlyphID(charCode));
+        rec->fGlyph = this->lookupMetrics(id, kFull_MetricsType);
+    } else {
+        RecordHashSuccess();
+        if (rec->fGlyph->isJustAdvance()) {
+            fScalerContext->getMetrics(rec->fGlyph);
+        }
+    }
+    SkASSERT(rec->fGlyph->isFullMetrics());
+    return *rec->fGlyph;
 }
 
 const SkGlyph& SkGlyphCache::getUnicharMetrics(SkUnichar charCode,
                                                SkFixed x, SkFixed y) {
     VALIDATE();
-    return *this->lookupByChar(charCode, kFull_MetricsType, x, y);
-}
-
-const SkGlyph& SkGlyphCache::getGlyphIDMetrics(uint16_t glyphID) {
-    VALIDATE();
-    uint32_t id = SkGlyph::MakeID(glyphID);
-    return *this->lookupByCombinedID(id, kFull_MetricsType);
-}
-
-const SkGlyph& SkGlyphCache::getGlyphIDMetrics(uint16_t glyphID, SkFixed x, SkFixed y) {
-    VALIDATE();
-    uint32_t id = SkGlyph::MakeID(glyphID, x, y);
-    return *this->lookupByCombinedID(id, kFull_MetricsType);
-}
-
-SkGlyph* SkGlyphCache::lookupByChar(SkUnichar charCode, MetricsType type, SkFixed x, SkFixed y) {
     uint32_t id = SkGlyph::MakeID(charCode, x, y);
     CharGlyphRec* rec = this->getCharGlyphRec(id);
-    SkGlyph* glyph;
+
     if (rec->fID != id) {
-        RecordHashCollisionIf(glyph_index != kSentinelGlyphIndex);
+        RecordHashCollisionIf(rec->fGlyph != NULL);
         // this ID is based on the UniChar
         rec->fID = id;
         // this ID is based on the glyph index
         id = SkGlyph::MakeID(fScalerContext->charToGlyphID(charCode), x, y);
-        rec->fGlyphIndex = this->lookupMetrics(id, type);
-        glyph = &fGlyphArray[rec->fGlyphIndex];
+        rec->fGlyph = this->lookupMetrics(id, kFull_MetricsType);
     } else {
         RecordHashSuccess();
-        glyph = &fGlyphArray[rec->fGlyphIndex];
-        if (type == kFull_MetricsType && glyph->isJustAdvance()) {
-            fScalerContext->getMetrics(glyph);
+        if (rec->fGlyph->isJustAdvance()) {
+            fScalerContext->getMetrics(rec->fGlyph);
         }
     }
-    return glyph;
+    SkASSERT(rec->fGlyph->isFullMetrics());
+    return *rec->fGlyph;
 }
 
-SkGlyph* SkGlyphCache::lookupByCombinedID(uint32_t id, MetricsType type) {
-    uint32_t hash_index = ID2HashIndex(id);
-    uint16_t glyph_index = fGlyphHash[hash_index];
-    SkGlyph* glyph = &fGlyphArray[glyph_index];
-    
-    if (glyph->fID != id) {
-        RecordHashCollisionIf(glyph_index != kSentinelGlyphIndex);
-        glyph_index = this->lookupMetrics(id, type);
-        fGlyphHash[hash_index] = glyph_index;
-        glyph = &fGlyphArray[glyph_index];
+const SkGlyph& SkGlyphCache::getGlyphIDMetrics(uint16_t glyphID) {
+    VALIDATE();
+    uint32_t id = SkGlyph::MakeID(glyphID);
+    unsigned index = ID2HashIndex(id);
+    SkGlyph* glyph = fGlyphHash[index];
+
+    if (NULL == glyph || glyph->fID != id) {
+        RecordHashCollisionIf(glyph != NULL);
+        glyph = this->lookupMetrics(glyphID, kFull_MetricsType);
+        fGlyphHash[index] = glyph;
     } else {
         RecordHashSuccess();
-        if (type == kFull_MetricsType && glyph->isJustAdvance()) {
-           fScalerContext->getMetrics(glyph);
+        if (glyph->isJustAdvance()) {
+            fScalerContext->getMetrics(glyph);
         }
     }
-    return glyph;
+    SkASSERT(glyph->isFullMetrics());
+    return *glyph;
 }
 
-uint16_t SkGlyphCache::lookupMetrics(uint32_t id, MetricsType mtype) {
-    // Count is always greater than 0 because of the sentinel.
-    SkGlyph* gptr = fGlyphArray.begin();
-    int lo = 0;
-    int hi = fGlyphArray.count() - 1;
-    while (lo < hi) {
-        int mid = (hi + lo) >> 1;
-        if (gptr[mid].fID < id) {
-            lo = mid + 1;
-        } else {
-            hi = mid;
-        }
-    }
+const SkGlyph& SkGlyphCache::getGlyphIDMetrics(uint16_t glyphID, SkFixed x, SkFixed y) {
+    VALIDATE();
+    uint32_t id = SkGlyph::MakeID(glyphID, x, y);
+    unsigned index = ID2HashIndex(id);
+    SkGlyph* glyph = fGlyphHash[index];
 
-    uint16_t glyph_index = hi;
-    SkGlyph* glyph = &gptr[glyph_index];
-    if (glyph->fID == id) {
-        if (kFull_MetricsType == mtype && glyph->isJustAdvance()) {
+    if (NULL == glyph || glyph->fID != id) {
+        RecordHashCollisionIf(glyph != NULL);
+        glyph = this->lookupMetrics(id, kFull_MetricsType);
+        fGlyphHash[index] = glyph;
+    } else {
+        RecordHashSuccess();
+        if (glyph->isJustAdvance()) {
             fScalerContext->getMetrics(glyph);
         }
-        SkASSERT(glyph_index != kSentinelGlyphIndex);
-        return glyph_index;
     }
+    SkASSERT(glyph->isFullMetrics());
+    return *glyph;
+}
+
+SkGlyph* SkGlyphCache::lookupMetrics(uint32_t id, MetricsType mtype) {
+    SkGlyph* glyph;
+
+    int     hi = 0;
+    int     count = fGlyphArray.count();
 
-    // check if we need to bump hi before falling though to the allocator
-    if (glyph->fID < id) {
-        glyph_index += 1;
+    if (count) {
+        SkGlyph**   gptr = fGlyphArray.begin();
+        int     lo = 0;
+
+        hi = count - 1;
+        while (lo < hi) {
+            int mid = (hi + lo) >> 1;
+            if (gptr[mid]->fID < id) {
+                lo = mid + 1;
+            } else {
+                hi = mid;
+            }
+        }
+        glyph = gptr[hi];
+        if (glyph->fID == id) {
+            if (kFull_MetricsType == mtype && glyph->isJustAdvance()) {
+                fScalerContext->getMetrics(glyph);
+            }
+            return glyph;
+        }
+
+        // check if we need to bump hi before falling though to the allocator
+        if (glyph->fID < id) {
+            hi += 1;
+        }
     }
-  
+
     // not found, but hi tells us where to inser the new glyph
     fMemoryUsed += sizeof(SkGlyph);
-  
-    this->adjustCaches(glyph_index);
 
-    glyph = fGlyphArray.insert(glyph_index);
+    glyph = (SkGlyph*)fGlyphAlloc.alloc(sizeof(SkGlyph),
+                                        SkChunkAlloc::kThrow_AllocFailType);
     glyph->init(id);
+    *fGlyphArray.insert(hi) = glyph;
 
     if (kJustAdvance_MetricsType == mtype) {
         fScalerContext->getAdvance(glyph);
@@ -303,8 +324,7 @@ uint16_t SkGlyphCache::lookupMetrics(uint32_t id, MetricsType mtype) {
         fScalerContext->getMetrics(glyph);
     }
 
-    SkASSERT(glyph_index != kSentinelGlyphIndex);
-    return glyph_index;
+    return glyph;
 }
 
 const void* SkGlyphCache::findImage(const SkGlyph& glyph) {
diff --git a/src/core/SkGlyphCache.h b/src/core/SkGlyphCache.h
index 8805085468..b335d29d2d 100644
--- a/src/core/SkGlyphCache.h
+++ b/src/core/SkGlyphCache.h
@@ -187,48 +187,32 @@ private:
         kFull_MetricsType
     };
 
-    // Return the SkGlyph* associated with MakeID. The id parameter is the combined glyph/x/y
-    // id generated by MakeID. If it is just a glyph id then x and y are assuemd to be zero.
-    SkGlyph* lookupByCombinedID(uint32_t id, MetricsType type);
-
-    // Return a SkGlyph* associated with unicode id and position x and y.
-    SkGlyph* lookupByChar(SkUnichar id, MetricsType type, SkFixed x = 0, SkFixed y = 0);
-
-    // Return the index of id in the fGlyphArray. If it does
-    // not exist, create a new one using MaetricsType.
-    uint16_t lookupMetrics(uint32_t id, MetricsType type);
+    SkGlyph* lookupMetrics(uint32_t id, MetricsType);
     static bool DetachProc(const SkGlyphCache*, void*) { return true; }
 
-    SkGlyphCache*        fNext, *fPrev;
-    SkDescriptor*        fDesc;
-    SkScalerContext*     fScalerContext;
+    SkGlyphCache*       fNext, *fPrev;
+    SkDescriptor*       fDesc;
+    SkScalerContext*    fScalerContext;
     SkPaint::FontMetrics fFontMetrics;
 
     enum {
-        kHashBits           = 8,
-        kHashCount          = 1 << kHashBits,
-        kHashMask           = kHashCount - 1,
-        kSentinelGlyphIndex = 0,
-        kSentinelGlyphID    = 0
+        kHashBits   = 8,
+        kHashCount  = 1 << kHashBits,
+        kHashMask   = kHashCount - 1
     };
-    
-    // A quick lookup to avoid the binary search looking for glyphs in fGlyphArray.
-    uint16_t             fGlyphHash[kHashCount];
-    SkTDArray<SkGlyph>   fGlyphArray;
-    SkChunkAlloc         fGlyphAlloc;
+    SkGlyph*            fGlyphHash[kHashCount];
+    SkTDArray<SkGlyph*> fGlyphArray;
+    SkChunkAlloc        fGlyphAlloc;
 
     struct CharGlyphRec {
         uint32_t    fID;    // unichar + subpixel
-        uint16_t    fGlyphIndex;
+        SkGlyph*    fGlyph;
     };
-
     // no reason to use the same kHashCount as fGlyphHash, but we do for now
     // Dynamically allocated when chars are encountered.
     SkAutoTArray<CharGlyphRec> fCharToGlyphHash;
-
-    // The id arg is a combined id generated by MakeID.
+    
     CharGlyphRec* getCharGlyphRec(uint32_t id);
-    void adjustCaches(int insertion_index);
 
     static inline unsigned ID2HashIndex(uint32_t h) {
         return SkChecksum::CheapMix(h) & kHashMask;