Don't use analytic clip FPs when drawing to stencil

It doesn't make sense to multiply by coverage when drawing to stencil.
This could theoretically work with FPs that discard and/or modify
the sample mask, but for the time being an analytic FP means one that
calculates a coverage value.

Bug: skia:7190
Change-Id: Ic40cf6c19c377cba80bad458993582f5cc07022a
Reviewed-on: https://skia-review.googlesource.com/67423
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>

13 files changed, 201 insertions, 120 deletions

diff --git a/gm/windowrectangles.cpp b/gm/windowrectangles.cpp
index b4f6562985..6a3f2a1eb0 100644
--- a/gm/windowrectangles.cpp
+++ b/gm/windowrectangles.cpp
@@ -12,7 +12,7 @@
 
 #if SK_SUPPORT_GPU
 #  include "GrAppliedClip.h"
-#  include "GrFixedClip.h"
+#  include "GrStencilClip.h"
 #  include "GrReducedClip.h"
 #  include "GrRenderTargetContext.h"
 #  include "GrRenderTargetContextPriv.h"
@@ -166,15 +166,10 @@ private:
 };
 
 /**
- * This class clips a cover by the stencil clip bit. We use it to visualize the stencil mask.
+ * Makes a clip object that enforces the stencil clip bit. Used to visualize the stencil mask.
  */
-class StencilOnlyClip final : public MaskOnlyClipBase {
-private:
-    bool apply(GrContext*, GrRenderTargetContext*, bool, bool, GrAppliedClip* out,
-               SkRect* bounds) const override {
-        out->addStencilClip(SkClipStack::kEmptyGenID);
-        return true;
-    }
+static GrStencilClip make_stencil_only_clip() {
+    return GrStencilClip(SkClipStack::kEmptyGenID);
 };
 
 void WindowRectanglesMaskGM::onCoverClipStack(const SkClipStack& stack, SkCanvas* canvas) {
@@ -215,7 +210,7 @@ void WindowRectanglesMaskGM::visualizeAlphaMask(GrContext* ctx, GrRenderTargetCo
     // the clip mask generation.
     this->stencilCheckerboard(maskRTC.get(), true);
     maskRTC->clear(nullptr, GrColorPackA4(0xff), true);
-    maskRTC->priv().drawAndStencilRect(StencilOnlyClip(), &GrUserStencilSettings::kUnused,
+    maskRTC->priv().drawAndStencilRect(make_stencil_only_clip(), &GrUserStencilSettings::kUnused,
                                        SkRegion::kDifference_Op, false, GrAA::kNo, SkMatrix::I(),
                                        SkRect::MakeIWH(maskRTC->width(), maskRTC->height()));
     reducedClip.drawAlphaClipMask(maskRTC.get());
@@ -242,7 +237,7 @@ void WindowRectanglesMaskGM::visualizeStencilMask(GrContext* ctx, GrRenderTarget
     // Now visualize the stencil mask by covering the entire render target. The regions inside
     // window rectangles or outside the scissor should still have the initial checkerboard intact.
     // (This verifies we didn't spend any time modifying those pixels in the mask.)
-    rtc->drawPaint(StencilOnlyClip(), std::move(paint), SkMatrix::I());
+    rtc->drawPaint(make_stencil_only_clip(), std::move(paint), SkMatrix::I());
 }
 
 void WindowRectanglesMaskGM::stencilCheckerboard(GrRenderTargetContext* rtc, bool flip) {
diff --git a/gn/gpu.gni b/gn/gpu.gni
index 185d6d899e..c364c29f03 100644
--- a/gn/gpu.gni
+++ b/gn/gpu.gni
@@ -177,6 +177,7 @@ skia_gpu_sources = [
   "$_src/gpu/GrShape.h",
   "$_src/gpu/GrStencilAttachment.cpp",
   "$_src/gpu/GrStencilAttachment.h",
+  "$_src/gpu/GrStencilClip.h",
   "$_src/gpu/GrStencilSettings.cpp",
   "$_src/gpu/GrStencilSettings.h",
   "$_src/gpu/GrStyle.cpp",
diff --git a/src/gpu/GrAppliedClip.h b/src/gpu/GrAppliedClip.h
index d96370ecc0..bfe3383e16 100644
--- a/src/gpu/GrAppliedClip.h
+++ b/src/gpu/GrAppliedClip.h
@@ -14,28 +14,21 @@
 
 #include "SkClipStack.h"
 
+
 /**
- * Produced by GrClip. It provides a set of modifications to the drawing state that are used to
- * create the final GrPipeline for a GrOp.
+ * Produced by GrHardClip. It provides a set of modifications to the hardware drawing state that
+ * implement the clip.
  */
-class GrAppliedClip {
+class GrAppliedHardClip {
 public:
-    GrAppliedClip() = default;
-    GrAppliedClip(GrAppliedClip&& that) = default;
-    GrAppliedClip(const GrAppliedClip&) = delete;
+    GrAppliedHardClip() = default;
+    GrAppliedHardClip(GrAppliedHardClip&& that) = default;
+    GrAppliedHardClip(const GrAppliedHardClip&) = delete;
 
     const GrScissorState& scissorState() const { return fScissorState; }
     const GrWindowRectsState& windowRectsState() const { return fWindowRectsState; }
-    int numClipCoverageFragmentProcessors() const { return fClipCoverageFPs.count(); }
-    const GrFragmentProcessor* clipCoverageFragmentProcessor(int i) const {
-        SkASSERT(fClipCoverageFPs[i]);
-        return fClipCoverageFPs[i].get();
-    }
-    std::unique_ptr<const GrFragmentProcessor> detachClipCoverageFragmentProcessor(int i) {
-        SkASSERT(fClipCoverageFPs[i]);
-        return std::move(fClipCoverageFPs[i]);
-    }
-    bool hasStencilClip() const { return SkClipStack::kInvalidGenID != fClipStackID; }
+    uint32_t stencilStackID() const { return fStencilStackID; }
+    bool hasStencilClip() const { return SkClipStack::kInvalidGenID != fStencilStackID; }
 
     /**
      * Intersects the applied clip with the provided rect. Returns false if the draw became empty.
@@ -56,26 +49,65 @@ public:
         fWindowRectsState.set(windows, mode);
     }
 
+    void addStencilClip(uint32_t stencilStackID) {
+        SkASSERT(SkClipStack::kInvalidGenID == fStencilStackID);
+        fStencilStackID = stencilStackID;
+    }
+
+    bool doesClip() const {
+        return fScissorState.enabled() || this->hasStencilClip() || fWindowRectsState.enabled();
+    }
+
+    bool operator==(const GrAppliedHardClip& that) const {
+        return fScissorState == that.fScissorState &&
+               fWindowRectsState == that.fWindowRectsState &&
+               fStencilStackID == that.fStencilStackID;
+    }
+    bool operator!=(const GrAppliedHardClip& that) const { return !(*this == that); }
+
+private:
+    GrScissorState             fScissorState;
+    GrWindowRectsState         fWindowRectsState;
+    uint32_t                   fStencilStackID = SkClipStack::kInvalidGenID;
+};
+
+/**
+ * Produced by GrClip. It provides a set of modifications to GrPipeline that implement the clip.
+ */
+class GrAppliedClip {
+public:
+    GrAppliedClip() = default;
+    GrAppliedClip(GrAppliedClip&& that) = default;
+    GrAppliedClip(const GrAppliedClip&) = delete;
+
+    const GrScissorState& scissorState() const { return fHardClip.scissorState(); }
+    const GrWindowRectsState& windowRectsState() const { return fHardClip.windowRectsState(); }
+    uint32_t stencilStackID() const { return fHardClip.stencilStackID(); }
+    bool hasStencilClip() const { return fHardClip.hasStencilClip(); }
+    int numClipCoverageFragmentProcessors() const { return fClipCoverageFPs.count(); }
+    const GrFragmentProcessor* clipCoverageFragmentProcessor(int i) const {
+        SkASSERT(fClipCoverageFPs[i]);
+        return fClipCoverageFPs[i].get();
+    }
+    std::unique_ptr<const GrFragmentProcessor> detachClipCoverageFragmentProcessor(int i) {
+        SkASSERT(fClipCoverageFPs[i]);
+        return std::move(fClipCoverageFPs[i]);
+    }
+
+    GrAppliedHardClip& hardClip() { return fHardClip; }
+
     void addCoverageFP(std::unique_ptr<GrFragmentProcessor> fp) {
         SkASSERT(fp);
         fClipCoverageFPs.push_back(std::move(fp));
     }
 
-    void addStencilClip(uint32_t clipStackID) {
-        SkASSERT(SkClipStack::kInvalidGenID == fClipStackID);
-        fClipStackID = clipStackID;
-    }
-
     bool doesClip() const {
-        return fScissorState.enabled() || !fClipCoverageFPs.empty() || this->hasStencilClip() ||
-               fWindowRectsState.enabled();
+        return fHardClip.doesClip() || !fClipCoverageFPs.empty();
     }
 
     bool operator==(const GrAppliedClip& that) const {
-        if (fScissorState != that.fScissorState ||
-            fWindowRectsState != that.fWindowRectsState ||
-            fClipCoverageFPs.count() != that.fClipCoverageFPs.count() ||
-            fClipStackID != that.fClipStackID) {
+        if (fHardClip != that.fHardClip ||
+            fClipCoverageFPs.count() != that.fClipCoverageFPs.count()) {
             return false;
         }
         for (int i = 0; i < fClipCoverageFPs.count(); ++i) {
@@ -102,10 +134,8 @@ public:
     }
 
 private:
-    GrScissorState             fScissorState;
-    GrWindowRectsState         fWindowRectsState;
+    GrAppliedHardClip fHardClip;
     SkSTArray<4, std::unique_ptr<GrFragmentProcessor>> fClipCoverageFPs;
-    uint32_t                   fClipStackID = SkClipStack::kInvalidGenID;
 };
 
 #endif
diff --git a/src/gpu/GrClip.h b/src/gpu/GrClip.h
index bd7d8a1d96..7358e67cb3 100644
--- a/src/gpu/GrClip.h
+++ b/src/gpu/GrClip.h
@@ -8,13 +8,12 @@
 #ifndef GrClip_DEFINED
 #define GrClip_DEFINED
 
-#include "GrTypes.h"
+#include "GrAppliedClip.h"
+#include "GrRenderTargetContext.h"
 #include "SkRRect.h"
 #include "SkRect.h"
 
-class GrAppliedClip;
 class GrContext;
-class GrRenderTargetContext;
 
 /**
  * GrClip is an abstract base class for applying a clip. It constructs a clip mask if necessary, and
@@ -37,8 +36,7 @@ public:
      * skipped as it is fully clipped out.
      */
     virtual bool apply(GrContext*, GrRenderTargetContext*, bool useHWAA,
-                       bool hasUserStencilSettings, GrAppliedClip* result,
-                       SkRect* bounds) const = 0;
+                       bool hasUserStencilSettings, GrAppliedClip*, SkRect* bounds) const = 0;
 
     virtual ~GrClip() {}
 
@@ -133,10 +131,32 @@ public:
     }
 };
 
+
+/**
+ * GrHardClip never uses coverage FPs. It can only enforce the clip using the already-existing
+ * stencil buffer contents and/or fixed-function state like scissor. Always aliased if MSAA is off.
+ */
+class GrHardClip : public GrClip {
+public:
+    /**
+     * Sets the appropriate hardware state modifications on GrAppliedHardClip that will implement
+     * the clip. On input 'bounds' is a conservative bounds of the draw that is to be clipped. After
+     * return 'bounds' has been intersected with a conservative bounds of the clip. A return value
+     * of false indicates that the draw can be skipped as it is fully clipped out.
+     */
+    virtual bool apply(int rtWidth, int rtHeight, GrAppliedHardClip* out, SkRect* bounds) const = 0;
+
+private:
+    bool apply(GrContext*, GrRenderTargetContext* rtc, bool useHWAA, bool hasUserStencilSettings,
+               GrAppliedClip* out, SkRect* bounds) const final {
+        return this->apply(rtc->width(), rtc->height(), &out->hardClip(), bounds);
+    }
+};
+
 /**
  * Specialized implementation for no clip.
  */
-class GrNoClip final : public GrClip {
+class GrNoClip final : public GrHardClip {
 private:
     bool quickContains(const SkRect&) const final { return true; }
     bool quickContains(const SkRRect&) const final { return true; }
@@ -147,10 +167,7 @@ private:
             *isIntersectionOfRects = true;
         }
     }
-    bool apply(GrContext*, GrRenderTargetContext*, bool, bool, GrAppliedClip*,
-               SkRect*) const final {
-        return true;
-    }
+    bool apply(int rtWidth, int rtHeight, GrAppliedHardClip*, SkRect*) const final { return true; }
     bool isRRect(const SkRect&, SkRRect*, GrAA*) const override { return false; }
 };
 
diff --git a/src/gpu/GrClipStackClip.cpp b/src/gpu/GrClipStackClip.cpp
index aa2b9fdd29..245f2d0cd8 100644
--- a/src/gpu/GrClipStackClip.cpp
+++ b/src/gpu/GrClipStackClip.cpp
@@ -269,12 +269,12 @@ bool GrClipStackClip::apply(GrContext* context, GrRenderTargetContext* renderTar
                                     renderTargetContext->priv().maxWindowRectangles());
 
     if (reducedClip.hasScissor() && !GrClip::IsInsideClip(reducedClip.scissor(), devBounds)) {
-        out->addScissor(reducedClip.scissor(), bounds);
+        out->hardClip().addScissor(reducedClip.scissor(), bounds);
     }
 
     if (!reducedClip.windowRectangles().empty()) {
-        out->addWindowRectangles(reducedClip.windowRectangles(),
-                                 GrWindowRectsState::Mode::kExclusive);
+        out->hardClip().addWindowRectangles(reducedClip.windowRectangles(),
+                                            GrWindowRectsState::Mode::kExclusive);
     }
 
     if (reducedClip.maskElements().isEmpty()) {
@@ -358,7 +358,7 @@ bool GrClipStackClip::apply(GrContext* context, GrRenderTargetContext* renderTar
         reducedClip.drawStencilClipMask(context, renderTargetContext);
         renderTargetContext->priv().setLastClip(reducedClip.maskGenID(), reducedClip.scissor());
     }
-    out->addStencilClip(reducedClip.maskGenID());
+    out->hardClip().addStencilClip(reducedClip.maskGenID());
     return true;
 }
 
diff --git a/src/gpu/GrFixedClip.cpp b/src/gpu/GrFixedClip.cpp
index e551f9b966..94a89fd034 100644
--- a/src/gpu/GrFixedClip.cpp
+++ b/src/gpu/GrFixedClip.cpp
@@ -45,10 +45,9 @@ bool GrFixedClip::isRRect(const SkRect& rtBounds, SkRRect* rr, GrAA* aa) const {
     return false;
 };
 
-bool GrFixedClip::apply(GrContext*, GrRenderTargetContext* rtc, bool, bool, GrAppliedClip* out,
-                        SkRect* bounds) const {
+bool GrFixedClip::apply(int rtWidth, int rtHeight, GrAppliedHardClip* out, SkRect* bounds) const {
     if (fScissorState.enabled()) {
-        SkIRect tightScissor = SkIRect::MakeWH(rtc->width(), rtc->height());
+        SkIRect tightScissor = SkIRect::MakeWH(rtWidth, rtHeight);
         if (!tightScissor.intersect(fScissorState.rect())) {
             return false;
         }
diff --git a/src/gpu/GrFixedClip.h b/src/gpu/GrFixedClip.h
index 744bb27a81..d44c1e84e4 100644
--- a/src/gpu/GrFixedClip.h
+++ b/src/gpu/GrFixedClip.h
@@ -13,9 +13,9 @@
 #include "GrWindowRectsState.h"
 
 /**
- * GrFixedClip is a clip that gets implemented by fixed-function hardware.
+ * Implements GrHardClip with scissor and window rectangles.
  */
-class GrFixedClip final : public GrClip {
+class GrFixedClip final : public GrHardClip {
 public:
     GrFixedClip() = default;
     explicit GrFixedClip(const SkIRect& scissorRect) : fScissorState(scissorRect) {}
@@ -26,6 +26,9 @@ public:
 
     void disableScissor() { fScissorState.setDisabled(); }
 
+    void setScissor(const SkIRect& irect) {
+        fScissorState.set(irect);
+    }
     bool SK_WARN_UNUSED_RESULT intersect(const SkIRect& irect) {
         return fScissorState.intersect(irect);
     }
@@ -42,8 +45,7 @@ public:
     bool quickContains(const SkRect&) const override;
     void getConservativeBounds(int w, int h, SkIRect* devResult, bool* iior) const override;
     bool isRRect(const SkRect& rtBounds, SkRRect* rr, GrAA*) const override;
-    bool apply(GrContext*, GrRenderTargetContext*, bool, bool, GrAppliedClip*,
-               SkRect*) const override;
+    bool apply(int rtWidth, int rtHeight, GrAppliedHardClip*, SkRect*) const override;
 
     static const GrFixedClip& Disabled();
 
diff --git a/src/gpu/GrPathRenderer.h b/src/gpu/GrPathRenderer.h
index 4a7fb92e9f..c5a1f63fa1 100644
--- a/src/gpu/GrPathRenderer.h
+++ b/src/gpu/GrPathRenderer.h
@@ -19,6 +19,7 @@
 
 class SkPath;
 class GrFixedClip;
+class GrHardClip;
 struct GrPoint;
 
 /**
@@ -168,7 +169,7 @@ public:
 
         GrContext*             fContext;
         GrRenderTargetContext* fRenderTargetContext;
-        const GrClip*          fClip;
+        const GrHardClip*      fClip;
         const SkIRect*         fClipConservativeBounds;
         const SkMatrix*        fViewMatrix;
         GrAAType               fAAType;
diff --git a/src/gpu/GrReducedClip.cpp b/src/gpu/GrReducedClip.cpp
index bc3286bdf0..d37c83f11a 100644
--- a/src/gpu/GrReducedClip.cpp
+++ b/src/gpu/GrReducedClip.cpp
@@ -17,6 +17,7 @@
 #include "GrFixedClip.h"
 #include "GrPathRenderer.h"
 #include "GrStencilSettings.h"
+#include "GrStencilClip.h"
 #include "GrStyle.h"
 #include "GrUserStencilSettings.h"
 #include "SkClipOpPriv.h"
@@ -695,52 +696,14 @@ bool GrReducedClip::drawAlphaClipMask(GrRenderTargetContext* rtc) const {
 ////////////////////////////////////////////////////////////////////////////////
 // Create a 1-bit clip mask in the stencil buffer.
 
-class StencilClip final : public GrClip {
-public:
-    StencilClip(const SkIRect& scissorRect, uint32_t clipStackID)
-        : fFixedClip(scissorRect)
-        , fClipStackID(clipStackID) {
-    }
-
-    const GrFixedClip& fixedClip() const { return fFixedClip; }
-
-    void setWindowRectangles(const GrWindowRectangles& windows, GrWindowRectsState::Mode mode) {
-        fFixedClip.setWindowRectangles(windows, mode);
-    }
-
-private:
-    bool quickContains(const SkRect&) const override {
-        return false;
-    }
-    void getConservativeBounds(int width, int height, SkIRect* bounds, bool* iior) const override {
-        fFixedClip.getConservativeBounds(width, height, bounds, iior);
-    }
-    bool isRRect(const SkRect& rtBounds, SkRRect* rr, GrAA*) const override {
-        return false;
-    }
-    bool apply(GrContext* context, GrRenderTargetContext* renderTargetContext, bool useHWAA,
-               bool hasUserStencilSettings, GrAppliedClip* out, SkRect* bounds) const override {
-        if (!fFixedClip.apply(context, renderTargetContext, useHWAA, hasUserStencilSettings, out,
-                              bounds)) {
-            return false;
-        }
-        out->addStencilClip(fClipStackID);
-        return true;
-    }
-
-    GrFixedClip fFixedClip;
-    uint32_t    fClipStackID;
-
-    typedef GrClip INHERITED;
-};
-
 bool GrReducedClip::drawStencilClipMask(GrContext* context,
                                         GrRenderTargetContext* renderTargetContext) const {
     // We set the current clip to the bounds so that our recursive draws are scissored to them.
-    StencilClip stencilClip(fScissor, this->maskGenID());
+    GrStencilClip stencilClip(fScissor, this->maskGenID());
 
     if (!fWindowRects.empty()) {
-        stencilClip.setWindowRectangles(fWindowRects, GrWindowRectsState::Mode::kExclusive);
+        stencilClip.fixedClip().setWindowRectangles(fWindowRects,
+                                                    GrWindowRectsState::Mode::kExclusive);
     }
 
     bool initialState = InitialState::kAllIn == this->initialState();
diff --git a/src/gpu/GrRenderTargetContext.cpp b/src/gpu/GrRenderTargetContext.cpp
index e1ce24c886..b259d7831f 100644
--- a/src/gpu/GrRenderTargetContext.cpp
+++ b/src/gpu/GrRenderTargetContext.cpp
@@ -623,7 +623,7 @@ void GrRenderTargetContextPriv::clearStencilClip(const GrFixedClip& clip, bool i
     fRenderTargetContext->getRTOpList()->addOp(std::move(op), *fRenderTargetContext->caps());
 }
 
-void GrRenderTargetContextPriv::stencilPath(const GrClip& clip,
+void GrRenderTargetContextPriv::stencilPath(const GrHardClip& clip,
                                             GrAAType aaType,
                                             const SkMatrix& viewMatrix,
                                             const GrPath* path) {
@@ -645,16 +645,12 @@ void GrRenderTargetContextPriv::stencilPath(const GrClip& clip,
     SkRect bounds = SkRect::MakeIWH(fRenderTargetContext->width(), fRenderTargetContext->height());
 
     // Setup clip
-    GrAppliedClip appliedClip;
-    if (!clip.apply(fRenderTargetContext->fContext, fRenderTargetContext, useHWAA, true,
-                    &appliedClip, &bounds)) {
+    GrAppliedHardClip appliedClip;
+    if (!clip.apply(fRenderTargetContext->width(), fRenderTargetContext->height(), &appliedClip,
+                    &bounds)) {
         return;
     }
 
-    // Coverage AA does not make sense when rendering to the stencil buffer. The caller should never
-    // attempt this in a situation that would require coverage AA.
-    SkASSERT(!appliedClip.numClipCoverageFragmentProcessors());
-
     fRenderTargetContext->setNeedsStencil();
 
     std::unique_ptr<GrOp> op = GrStencilPathOp::Make(viewMatrix,
@@ -670,7 +666,7 @@ void GrRenderTargetContextPriv::stencilPath(const GrClip& clip,
     fRenderTargetContext->getRTOpList()->addOp(std::move(op), *fRenderTargetContext->caps());
 }
 
-void GrRenderTargetContextPriv::stencilRect(const GrClip& clip,
+void GrRenderTargetContextPriv::stencilRect(const GrHardClip& clip,
                                             const GrUserStencilSettings* ss,
                                             GrAAType aaType,
                                             const SkMatrix& viewMatrix,
@@ -691,7 +687,7 @@ void GrRenderTargetContextPriv::stencilRect(const GrClip& clip,
     fRenderTargetContext->addDrawOp(clip, std::move(op));
 }
 
-bool GrRenderTargetContextPriv::drawAndStencilRect(const GrClip& clip,
+bool GrRenderTargetContextPriv::drawAndStencilRect(const GrHardClip& clip,
                                                    const GrUserStencilSettings* ss,
                                                    SkRegion::Op op,
                                                    bool invert,
@@ -1594,7 +1590,7 @@ void GrRenderTargetContext::drawPath(const GrClip& clip,
     this->internalDrawPath(clip, std::move(paint), aa, viewMatrix, path, style);
 }
 
-bool GrRenderTargetContextPriv::drawAndStencilPath(const GrClip& clip,
+bool GrRenderTargetContextPriv::drawAndStencilPath(const GrHardClip& clip,
                                                    const GrUserStencilSettings* ss,
                                                    SkRegion::Op op,
                                                    bool invert,
diff --git a/src/gpu/GrRenderTargetContextPriv.h b/src/gpu/GrRenderTargetContextPriv.h
index 2cfd5c8679..874e9c9f00 100644
--- a/src/gpu/GrRenderTargetContextPriv.h
+++ b/src/gpu/GrRenderTargetContextPriv.h
@@ -13,6 +13,7 @@
 #include "GrPathRendering.h"
 
 class GrFixedClip;
+class GrHardClip;
 class GrPath;
 class GrRenderTargetPriv;
 struct GrUserStencilSettings;
@@ -59,19 +60,19 @@ public:
      */
     void absClear(const SkIRect* rect, const GrColor color);
 
-    void stencilRect(const GrClip& clip,
+    void stencilRect(const GrHardClip&,
                      const GrUserStencilSettings* ss,
                      GrAAType,
                      const SkMatrix& viewMatrix,
                      const SkRect& rect);
 
-    void stencilPath(const GrClip&, GrAAType, const SkMatrix& viewMatrix, const GrPath*);
+    void stencilPath(const GrHardClip&, GrAAType, const SkMatrix& viewMatrix, const GrPath*);
 
     /**
      * Draws a rect, either AA or not, and touches the stencil buffer with the user stencil settings
      * for each color sample written.
      */
-    bool drawAndStencilRect(const GrClip&,
+    bool drawAndStencilRect(const GrHardClip&,
                             const GrUserStencilSettings*,
                             SkRegion::Op op,
                             bool invert,
@@ -83,7 +84,7 @@ public:
      * Draws a path, either AA or not, and touches the stencil buffer with the user stencil settings
      * for each color sample written.
      */
-    bool drawAndStencilPath(const GrClip&,
+    bool drawAndStencilPath(const GrHardClip&,
                             const GrUserStencilSettings*,
                             SkRegion::Op op,
                             bool invert,
diff --git a/src/gpu/GrStencilClip.h b/src/gpu/GrStencilClip.h
new file mode 100644
index 0000000000..2bbf3b44de
--- /dev/null
+++ b/src/gpu/GrStencilClip.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrStencilClip_DEFINED
+#define GrStencilClip_DEFINED
+
+#include "GrAppliedClip.h"
+#include "GrFixedClip.h"
+
+/**
+ * Implements GrHardClip with the currently-existing stencil buffer contents and GrFixedClip.
+ */
+class GrStencilClip final : public GrHardClip {
+public:
+    GrStencilClip(uint32_t stencilStackID = SK_InvalidGenID) : fStencilStackID(stencilStackID) {}
+
+    explicit GrStencilClip(const SkIRect& scissorRect, uint32_t stencilStackID = SK_InvalidGenID)
+        : fFixedClip(scissorRect)
+        , fStencilStackID(stencilStackID) {
+    }
+
+    const GrFixedClip& fixedClip() const { return fFixedClip; }
+    GrFixedClip& fixedClip() { return fFixedClip; }
+
+    bool stencilStackID() const { return fStencilStackID; }
+    bool hasStencilClip() const { return SK_InvalidGenID != fStencilStackID; }
+    void setStencilClip(uint32_t stencilStackID) { fStencilStackID = stencilStackID; }
+
+    bool quickContains(const SkRect& rect) const override {
+        return !this->hasStencilClip() && fFixedClip.quickContains(rect);
+    }
+    void getConservativeBounds(int width, int height, SkIRect* bounds, bool* iior) const override {
+        fFixedClip.getConservativeBounds(width, height, bounds, iior);
+    }
+    bool isRRect(const SkRect& rtBounds, SkRRect* rr, GrAA* aa) const override {
+        return !this->hasStencilClip() && fFixedClip.isRRect(rtBounds, rr, aa);
+    }
+    bool apply(int rtWidth, int rtHeight, GrAppliedHardClip* out, SkRect* bounds) const override {
+        if (!fFixedClip.apply(rtWidth, rtHeight, out, bounds)) {
+            return false;
+        }
+        if (this->hasStencilClip()) {
+            out->addStencilClip(fStencilStackID);
+        }
+        return true;
+    }
+
+private:
+    GrFixedClip   fFixedClip;
+    uint32_t      fStencilStackID;
+
+    typedef GrClip INHERITED;
+};
+
+#endif
diff --git a/src/gpu/ops/GrStencilAndCoverPathRenderer.cpp b/src/gpu/ops/GrStencilAndCoverPathRenderer.cpp
index 20c02c8f97..162d9d3714 100644
--- a/src/gpu/ops/GrStencilAndCoverPathRenderer.cpp
+++ b/src/gpu/ops/GrStencilAndCoverPathRenderer.cpp
@@ -14,6 +14,7 @@
 #include "GrPath.h"
 #include "GrRenderTargetContextPriv.h"
 #include "GrResourceProvider.h"
+#include "GrStencilClip.h"
 #include "GrStencilPathOp.h"
 #include "GrStyle.h"
 #include "ops/GrRectOpFactory.h"
@@ -114,7 +115,23 @@ bool GrStencilAndCoverPathRenderer::onDrawPath(const DrawPathArgs& args) {
         const SkMatrix& viewM = viewMatrix.hasPerspective() ? SkMatrix::I() : viewMatrix;
 
         // fake inverse with a stencil and cover
-        args.fRenderTargetContext->priv().stencilPath(*args.fClip, args.fAAType, viewMatrix,
+        GrAppliedClip appliedClip;
+        SkRect appliedBounds = bounds;
+        if (!args.fClip->apply(args.fContext, args.fRenderTargetContext,
+                               GrAATypeIsHW(args.fAAType), true, &appliedClip, &appliedBounds)) {
+            return true;
+        }
+        GrStencilClip stencilClip(appliedClip.stencilStackID());
+        if (appliedClip.scissorState().enabled()) {
+            stencilClip.fixedClip().setScissor(appliedClip.scissorState().rect());
+        }
+        if (appliedClip.windowRectsState().enabled()) {
+            stencilClip.fixedClip().setWindowRectangles(appliedClip.windowRectsState().windows(),
+                                                        appliedClip.windowRectsState().mode());
+        }
+        // Just ignore the analytic FPs (if any) during the stencil pass. They will still clip the
+        // final draw and it is meaningless to multiply by coverage when drawing to stencil.
+        args.fRenderTargetContext->priv().stencilPath(stencilClip, args.fAAType, viewMatrix,
                                                       path.get());
 
         {