Change mapRectScaleTranslate to pass args/ret by value

This reverts commit 6092b6e0e57be20d2e1ad079c0af133d2f67bfd3.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2138943002

Review-Url: https://codereview.chromium.org/2138943002

3 files changed, 15 insertions, 16 deletions

diff --git a/src/core/SkCanvas.cpp b/src/core/SkCanvas.cpp
index 24d9506bd7..63611443e6 100644
--- a/src/core/SkCanvas.cpp
+++ b/src/core/SkCanvas.cpp
@@ -77,13 +77,11 @@ bool SkCanvas::wouldOverwriteEntireSurface(const SkRect* rect, const SkPaint* pa
     }
 
     if (rect) {
-        if (!this->getTotalMatrix().isScaleTranslate()) {
+        const SkMatrix& ctm = this->getTotalMatrix();
+        if (!ctm.isScaleTranslate()) {
             return false; // conservative
         }
-
-        SkRect devRect;
-        this->getTotalMatrix().mapRectScaleTranslate(&devRect, *rect);
-        if (!devRect.contains(bounds)) {
+        if (!ctm.mapRectScaleTranslate(*rect).contains(bounds)) {
             return false;
         }
     }
@@ -1544,8 +1542,7 @@ void SkCanvas::clipRect(const SkRect& rect, SkRegion::Op op, bool doAA) {
     // Check if we can quick-accept the clip call (and do nothing)
     //
     if (SkRegion::kIntersect_Op == op && !doAA && fMCRec->fMatrix.isScaleTranslate()) {
-        SkRect devR;
-        fMCRec->fMatrix.mapRectScaleTranslate(&devR, rect);
+        SkRect devR = fMCRec->fMatrix.mapRectScaleTranslate(rect);
         // NOTE: this check is CTM specific, since we might round differently with a different
         //       CTM. Thus this is only 100% reliable if there is not global CTM scale to be
         //       applied later (i.e. if this is going into a picture).
@@ -1585,7 +1582,7 @@ void SkCanvas::onClipRect(const SkRect& rect, SkRegion::Op op, ClipEdgeStyle edg
     const bool isScaleTrans = fMCRec->fMatrix.isScaleTranslate();
     SkRect devR;
     if (isScaleTrans) {
-        fMCRec->fMatrix.mapRectScaleTranslate(&devR, rect);
+        devR = fMCRec->fMatrix.mapRectScaleTranslate(rect);
     }
 
 #ifndef SK_SUPPORT_PRECHECK_CLIPRECT
diff --git a/src/core/SkMatrix.cpp b/src/core/SkMatrix.cpp
index 0fd802087f..f9c8c9d07e 100644
--- a/src/core/SkMatrix.cpp
+++ b/src/core/SkMatrix.cpp
@@ -1097,8 +1097,7 @@ void SkMatrix::mapVectors(SkPoint dst[], const SkPoint src[], int count) const {
     }
 }
 
-void SkMatrix::mapRectScaleTranslate(SkRect* dst, const SkRect& src) const {
-    SkASSERT(dst);
+SkRect SkMatrix::mapRectScaleTranslate(SkRect src) const {
     SkASSERT(this->isScaleTranslate());
     
     SkScalar sx = fMat[kMScaleX];
@@ -1107,22 +1106,25 @@ void SkMatrix::mapRectScaleTranslate(SkRect* dst, const SkRect& src) const {
     SkScalar ty = fMat[kMTransY];
     Sk4f scale(sx, sy, sx, sy);
     Sk4f trans(tx, ty, tx, ty);
-
+    
     Sk4f ltrb = Sk4f::Load(&src.fLeft) * scale + trans;
     // need to sort so we're not inverted
     Sk4f rblt(ltrb[2], ltrb[3], ltrb[0], ltrb[1]);
     Sk4f min = Sk4f::Min(ltrb, rblt);
     Sk4f max = Sk4f::Max(ltrb, rblt);
-    // We can extract either pair [0,1] or [2,3] from min and max and be correct, but on
-    // ARM this sequence generates the fastest (a single instruction).
-    Sk4f(min[2], min[3], max[0], max[1]).store(&dst->fLeft);
+    // We can extract either pair [0,1] or [2,3] from min and max and be correct.
+    // However, the current ABI for returning multiple floats is to use only 2 slots in each
+    // vector register. Thus we take [0..1] from min and max, as that perfectly matches the ABI.
+    SkRect dst;
+    Sk4f(min[0], min[1], max[0], max[1]).store(&dst.fLeft);
+    return dst;
 }
 
 bool SkMatrix::mapRect(SkRect* dst, const SkRect& src) const {
     SkASSERT(dst);
 
     if (this->isScaleTranslate()) {
-        this->mapRectScaleTranslate(dst, src);
+        *dst = this->mapRectScaleTranslate(src);
         return true;
     } else {
         SkPoint quad[4];
diff --git a/src/utils/SkDeferredCanvas.cpp b/src/utils/SkDeferredCanvas.cpp
index 14220209cc..c8a37c36b7 100644
--- a/src/utils/SkDeferredCanvas.cpp
+++ b/src/utils/SkDeferredCanvas.cpp
@@ -200,7 +200,7 @@ void SkDeferredCanvas::flush_check(SkRect* bounds, const SkPaint* paint, unsigne
                 if (canScale) {
                     SkMatrix m;
                     rec.getConcat(&m);
-                    m.mapRectScaleTranslate(bounds, *bounds);
+                    *bounds = m.mapRectScaleTranslate(*bounds);
                 } else {
                     goto STOP;
                 }