Fix precision caps and rrect/ellipse effect precisions

Replaces all the complex precision caps with a single flag that says
whether "float" == fp32. Updates the ellipse and rrect effects to
use float coords, and use the scale workaround when float != fp32.

Bug: skia:7190
Change-Id: Ieccff9f38acd05e5cec78fe90d01a5da901a9307
Reviewed-on: https://skia-review.googlesource.com/70961
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>

10 files changed, 101 insertions, 287 deletions

diff --git a/src/gpu/GrProgramDesc.cpp b/src/gpu/GrProgramDesc.cpp
index a32e0cc28b..9c0add66e6 100644
--- a/src/gpu/GrProgramDesc.cpp
+++ b/src/gpu/GrProgramDesc.cpp
@@ -52,7 +52,7 @@ static uint16_t sampler_key(GrSLType samplerType, GrPixelConfig config, GrShader
     GR_STATIC_ASSERT(1 == sizeof(caps.configTextureSwizzle(config).asKey()));
     return SkToU16(samplerTypeKey |
                    caps.configTextureSwizzle(config).asKey() << kSamplerOrImageTypeKeyBits |
-                   (caps.samplerPrecision(config, visibility) << (8 + kSamplerOrImageTypeKeyBits)));
+                   (GrSLSamplerPrecision(config) << (8 + kSamplerOrImageTypeKeyBits)));
 }
 
 static void add_sampler_and_image_keys(GrProcessorKeyBuilder* b, const GrResourceIOProcessor& proc,
diff --git a/src/gpu/GrShaderCaps.cpp b/src/gpu/GrShaderCaps.cpp
index 124fd4de40..2d9cd0a39b 100644
--- a/src/gpu/GrShaderCaps.cpp
+++ b/src/gpu/GrShaderCaps.cpp
@@ -13,32 +13,6 @@
 
 ////////////////////////////////////////////////////////////////////////////////////////////
 
-static const char* shader_type_to_string(GrShaderType type) {
-    switch (type) {
-    case kVertex_GrShaderType:
-        return "vertex";
-    case kGeometry_GrShaderType:
-        return "geometry";
-    case kFragment_GrShaderType:
-        return "fragment";
-    }
-    return "";
-}
-
-static const char* precision_to_string(GrSLPrecision p) {
-    switch (p) {
-    case kLow_GrSLPrecision:
-        return "low";
-    case kMedium_GrSLPrecision:
-        return "medium";
-    case kHigh_GrSLPrecision:
-        return "high";
-    default:
-        SK_ABORT("Unexpected precision type.");
-        return "";
-    }
-}
-
 GrShaderCaps::GrShaderCaps(const GrContextOptions& options) {
     fGLSLGeneration = k330_GrGLSLGeneration;
     fShaderDerivativeSupport = false;
@@ -50,7 +24,6 @@ GrShaderCaps::GrShaderCaps(const GrContextOptions& options) {
     fIntegerSupport = false;
     fTexelBufferSupport = false;
     fImageLoadStoreSupport = false;
-    fShaderPrecisionVaries = false;
     fDropsTileOnZeroDivide = false;
     fFBFetchSupport = false;
     fFBFetchNeedsCustomOutput = false;
@@ -73,6 +46,8 @@ GrShaderCaps::GrShaderCaps(const GrContextOptions& options) {
     fExternalTextureSupport = false;
     fTexelFetchSupport = false;
     fVertexIDSupport = false;
+    fFloatIs32Bits = true;
+    fHalfIs32Bits = false;
 
     fVersionDeclString = nullptr;
     fShaderDerivativeExtensionString = nullptr;
@@ -113,26 +88,6 @@ void GrShaderCaps::dumpJSON(SkJSONWriter* writer) const {
     writer->appendBool("Texel Buffer Support", fTexelBufferSupport);
     writer->appendBool("Image Load Store Support", fImageLoadStoreSupport);
 
-    writer->appendBool("Variable Precision", fShaderPrecisionVaries);
-
-    for (int s = 0; s < kGrShaderTypeCount; ++s) {
-        GrShaderType shaderType = static_cast<GrShaderType>(s);
-        writer->beginArray(SkStringPrintf("%s precisions",
-                                          shader_type_to_string(shaderType)).c_str());
-        for (int p = 0; p < kGrSLPrecisionCount; ++p) {
-            if (fFloatPrecisions[s][p].supported()) {
-                GrSLPrecision precision = static_cast<GrSLPrecision>(p);
-                writer->beginObject(nullptr, false);
-                writer->appendString("precision", precision_to_string(precision));
-                writer->appendS32("log_low", fFloatPrecisions[s][p].fLogRangeLow);
-                writer->appendS32("log_high", fFloatPrecisions[s][p].fLogRangeHigh);
-                writer->appendS32("bits", fFloatPrecisions[s][p].fBits);
-                writer->endObject();
-            }
-        }
-        writer->endArray();
-    }
-
     static const char* kAdvBlendEqInteractionStr[] = {
         "Not Supported",
         "Automatic",
@@ -166,6 +121,8 @@ void GrShaderCaps::dumpJSON(SkJSONWriter* writer) const {
     writer->appendBool("External texture support", fExternalTextureSupport);
     writer->appendBool("texelFetch support", fTexelFetchSupport);
     writer->appendBool("sk_VertexID support", fVertexIDSupport);
+    writer->appendBool("float == fp32", fFloatIs32Bits);
+    writer->appendBool("half == fp32", fHalfIs32Bits);
 
     writer->appendS32("Max VS Samplers", fMaxVertexSamplers);
     writer->appendS32("Max GS Samplers", fMaxGeometrySamplers);
@@ -178,59 +135,6 @@ void GrShaderCaps::dumpJSON(SkJSONWriter* writer) const {
     writer->endObject();
 }
 
-void GrShaderCaps::initSamplerPrecisionTable() {
-    // Determine the largest precision qualifiers that are effectively the same as lowp/mediump.
-    //   e.g. if lowp == mediump, then use mediump instead of lowp.
-    GrSLPrecision effectiveMediumP[kGrShaderTypeCount];
-    GrSLPrecision effectiveLowP[kGrShaderTypeCount];
-    for (int s = 0; s < kGrShaderTypeCount; ++s) {
-        const PrecisionInfo* info = fFloatPrecisions[s];
-        effectiveMediumP[s] = info[kHigh_GrSLPrecision] == info[kMedium_GrSLPrecision] ?
-                                  kHigh_GrSLPrecision : kMedium_GrSLPrecision;
-        effectiveLowP[s] = info[kMedium_GrSLPrecision] == info[kLow_GrSLPrecision] ?
-                               effectiveMediumP[s] : kLow_GrSLPrecision;
-    }
-
-    // Determine which precision qualifiers should be used with samplers.
-    for (int visibility = 0; visibility < (1 << kGrShaderTypeCount); ++visibility) {
-        GrSLPrecision mediump = kHigh_GrSLPrecision;
-        GrSLPrecision lowp = kHigh_GrSLPrecision;
-        for (int s = 0; s < kGrShaderTypeCount; ++s) {
-            if (visibility & (1 << s)) {
-                mediump = SkTMin(mediump, effectiveMediumP[s]);
-                lowp = SkTMin(lowp, effectiveLowP[s]);
-            }
-
-            GR_STATIC_ASSERT(0 == kLow_GrSLPrecision);
-            GR_STATIC_ASSERT(1 == kMedium_GrSLPrecision);
-            GR_STATIC_ASSERT(2 == kHigh_GrSLPrecision);
-
-            GR_STATIC_ASSERT((1 << kVertex_GrShaderType) == kVertex_GrShaderFlag);
-            GR_STATIC_ASSERT((1 << kGeometry_GrShaderType) == kGeometry_GrShaderFlag);
-            GR_STATIC_ASSERT((1 << kFragment_GrShaderType) == kFragment_GrShaderFlag);
-            GR_STATIC_ASSERT(3 == kGrShaderTypeCount);
-        }
-
-        uint8_t* table = fSamplerPrecisions[visibility];
-        table[kUnknown_GrPixelConfig]        = lowp;
-        table[kAlpha_8_GrPixelConfig]        = lowp;
-        table[kGray_8_GrPixelConfig]         = lowp;
-        table[kRGB_565_GrPixelConfig]        = lowp;
-        table[kRGBA_4444_GrPixelConfig]      = lowp;
-        table[kRGBA_8888_GrPixelConfig]      = lowp;
-        table[kBGRA_8888_GrPixelConfig]      = lowp;
-        table[kSRGBA_8888_GrPixelConfig]     = lowp;
-        table[kSBGRA_8888_GrPixelConfig]     = lowp;
-        table[kRGBA_8888_sint_GrPixelConfig] = lowp;
-        table[kRGBA_float_GrPixelConfig]     = kHigh_GrSLPrecision;
-        table[kRG_float_GrPixelConfig]       = kHigh_GrSLPrecision;
-        table[kAlpha_half_GrPixelConfig]     = mediump;
-        table[kRGBA_half_GrPixelConfig]      = mediump;
-
-        GR_STATIC_ASSERT(14 == kGrPixelConfigCnt);
-    }
-}
-
 void GrShaderCaps::applyOptionsOverrides(const GrContextOptions& options) {
 #if GR_TEST_UTILS
     fDualSourceBlendingSupport = fDualSourceBlendingSupport && !options.fSuppressDualSourceBlending;
diff --git a/src/gpu/effects/GrEllipseEffect.cpp b/src/gpu/effects/GrEllipseEffect.cpp
index 4a0f37665c..6b1a8cc59f 100644
--- a/src/gpu/effects/GrEllipseEffect.cpp
+++ b/src/gpu/effects/GrEllipseEffect.cpp
@@ -28,34 +28,33 @@ public:
         (void)center;
         auto radii = _outer.radii();
         (void)radii;
-        prevRadii = half2(-1.0);
-        useScale = sk_Caps.floatPrecisionVaries;
+        prevRadii = float2(-1.0);
+        useScale = !sk_Caps.floatIs32Bits;
         fEllipseVar = args.fUniformHandler->addUniform(kFragment_GrShaderFlag, kFloat4_GrSLType,
                                                        kDefault_GrSLPrecision, "ellipse");
         if (useScale) {
-            fScaleVar = args.fUniformHandler->addUniform(kFragment_GrShaderFlag, kHalf2_GrSLType,
+            fScaleVar = args.fUniformHandler->addUniform(kFragment_GrShaderFlag, kFloat2_GrSLType,
                                                          kDefault_GrSLPrecision, "scale");
         }
         fragBuilder->codeAppendf(
-                "half2 prevCenter;\nhalf2 prevRadii = half2(%f, %f);\nbool useScale = %s;\nhalf2 d "
-                "= half2(sk_FragCoord.xy - %s.xy);\n@if (useScale) {\n    d *= %s.y;\n}\nhalf2 Z = "
-                "d * half2(%s.zw);\nhalf implicit = dot(Z, d) - 1.0;\nhalf grad_dot = 4.0 * dot(Z, "
-                "Z);\ngrad_dot = half(max(float(grad_dot), 0.0001));\nhalf approx_dist = "
-                "float(implicit) * inversesqrt(float(grad_dot));\n@if (useScale) {\n    "
-                "approx_dist *= %s.x;\n}\nhalf alpha;\n@switch (%d) {\n    case 0:\n        alpha "
-                "= half(float(approx_dist) > 0.0 ? 0.0 : 1.",
+                "float2 prevCenter;\nfloat2 prevRadii = float2(%f, %f);\nbool useScale = "
+                "%s;\nfloat2 d = sk_FragCoord.xy - %s.xy;\n@if (useScale) {\n    d *= "
+                "%s.y;\n}\nfloat2 Z = d * %s.zw;\nfloat implicit = dot(Z, d) - 1.0;\nfloat "
+                "grad_dot = 4.0 * dot(Z, Z);\ngrad_dot = max(grad_dot, 0.0001);\nfloat approx_dist "
+                "= implicit * inversesqrt(grad_dot);\n@if (useScale) {\n    approx_dist *= "
+                "%s.x;\n}\nhalf alpha;\n@switch (%d) {\n    case 0:\n        alpha = "
+                "half(approx_dist > 0.0 ? 0.0 : 1.0);\n        break;\n    case 1:\n      ",
                 prevRadii.fX, prevRadii.fY, (useScale ? "true" : "false"),
                 args.fUniformHandler->getUniformCStr(fEllipseVar),
-                fScaleVar.isValid() ? args.fUniformHandler->getUniformCStr(fScaleVar) : "half2(0)",
+                fScaleVar.isValid() ? args.fUniformHandler->getUniformCStr(fScaleVar) : "float2(0)",
                 args.fUniformHandler->getUniformCStr(fEllipseVar),
-                fScaleVar.isValid() ? args.fUniformHandler->getUniformCStr(fScaleVar) : "half2(0)",
+                fScaleVar.isValid() ? args.fUniformHandler->getUniformCStr(fScaleVar) : "float2(0)",
                 (int)_outer.edgeType());
         fragBuilder->codeAppendf(
-                "0);\n        break;\n    case 1:\n        alpha = half(clamp(0.5 - "
-                "float(approx_dist), 0.0, 1.0));\n        break;\n    case 2:\n        alpha = "
-                "half(float(approx_dist) > 0.0 ? 1.0 : 0.0);\n        break;\n    case 3:\n        "
-                "alpha = half(clamp(0.5 + float(approx_dist), 0.0, 1.0));\n        break;\n    "
-                "default:\n        discard;\n}\n%s = %s * alpha;\n",
+                "  alpha = half(clamp(0.5 - approx_dist, 0.0, 1.0));\n        break;\n    case "
+                "2:\n        alpha = half(approx_dist > 0.0 ? 1.0 : 0.0);\n        break;\n    "
+                "case 3:\n        alpha = half(clamp(0.5 + approx_dist, 0.0, 1.0));\n        "
+                "break;\n    default:\n        discard;\n}\n%s = %s * alpha;\n",
                 args.fOutputColor, args.fInputColor ? args.fInputColor : "half4(1)");
     }
 
diff --git a/src/gpu/effects/GrEllipseEffect.fp b/src/gpu/effects/GrEllipseEffect.fp
index 54641b72c6..27beb85d2f 100644
--- a/src/gpu/effects/GrEllipseEffect.fp
+++ b/src/gpu/effects/GrEllipseEffect.fp
@@ -6,17 +6,17 @@
  */
 
 layout(key) in GrClipEdgeType edgeType;
-in half2 center;
-in half2 radii;
+in float2 center;
+in float2 radii;
 
-half2 prevCenter;
-half2 prevRadii = half2(-1);
+float2 prevCenter;
+float2 prevRadii = float2(-1);
 // The ellipse uniform is (center.x, center.y, 1 / rx^2, 1 / ry^2)
-// The last two terms can underflow with halfs, so we use floats.
+// The last two terms can underflow when float != fp32, so we also provide a workaround.
 uniform float4 ellipse;
 
-bool useScale = sk_Caps.floatPrecisionVaries;
-layout(when=useScale) uniform half2 scale;
+bool useScale = !sk_Caps.floatIs32Bits;
+layout(when=useScale) uniform float2 scale;
 
 @optimizationFlags { kCompatibleWithCoverageAsAlpha_OptimizationFlag }
 
@@ -50,7 +50,7 @@ layout(when=useScale) uniform half2 scale;
 
 void main() {
     // d is the offset to the ellipse center
-    half2 d = sk_FragCoord.xy - ellipse.xy;
+    float2 d = sk_FragCoord.xy - ellipse.xy;
     // If we're on a device with a "real" mediump then we'll do the distance computation in a space
     // that is normalized by the larger radius. The scale uniform will be scale, 1/scale. The
     // inverse squared radii uniform values are already in this normalized space. The center is
@@ -58,14 +58,14 @@ void main() {
     @if (useScale) {
         d *= scale.y;
     }
-    half2 Z = d * ellipse.zw;
+    float2 Z = d * ellipse.zw;
     // implicit is the evaluation of (x/rx)^2 + (y/ry)^2 - 1.
-    half implicit = dot(Z, d) - 1;
+    float implicit = dot(Z, d) - 1;
     // grad_dot is the squared length of the gradient of the implicit.
-    half grad_dot = 4 * dot(Z, Z);
+    float grad_dot = 4 * dot(Z, Z);
     // Avoid calling inversesqrt on zero.
     grad_dot = max(grad_dot, 1e-4);
-    half approx_dist = implicit * inversesqrt(grad_dot);
+    float approx_dist = implicit * inversesqrt(grad_dot);
     @if (useScale) {
         approx_dist *= scale.x;
     }
@@ -102,4 +102,4 @@ void main() {
         et = (GrClipEdgeType) testData->fRandom->nextULessThan(kGrClipEdgeTypeCnt);
     } while (GrClipEdgeType::kHairlineAA == et);
     return GrEllipseEffect::Make(et, center, SkPoint::Make(rx, ry));
-}
\ No newline at end of file
+}
diff --git a/src/gpu/effects/GrRRectEffect.cpp b/src/gpu/effects/GrRRectEffect.cpp
index 4b56443b0d..510a26b425 100644
--- a/src/gpu/effects/GrRRectEffect.cpp
+++ b/src/gpu/effects/GrRRectEffect.cpp
@@ -165,9 +165,9 @@ void GLCircularRRectEffect::emitCode(EmitArgs& args) {
     fRadiusPlusHalfUniform = uniformHandler->addUniform(kFragment_GrShaderFlag, kHalf2_GrSLType,
                                                         "radiusPlusHalf", &radiusPlusHalfName);
 
-    // If we're on a device with a "real" mediump then the length calculation could overflow.
+    // If we're on a device where float != fp32 then the length calculation could overflow.
     SkString clampedCircleDistance;
-    if (args.fShaderCaps->floatPrecisionVaries()) {
+    if (!args.fShaderCaps->floatIs32Bits()) {
         clampedCircleDistance.printf("clamp(%s.x * (1.0 - length(dxy * %s.y)), 0.0, 1.0);",
                                      radiusPlusHalfName, radiusPlusHalfName);
     } else {
@@ -192,13 +192,13 @@ void GLCircularRRectEffect::emitCode(EmitArgs& args) {
     // alphas together.
     switch (crre.getCircularCornerFlags()) {
         case CircularRRectEffect::kAll_CornerFlags:
-            fragBuilder->codeAppendf("half2 dxy0 = %s.xy - sk_FragCoord.xy;", rectName);
-            fragBuilder->codeAppendf("half2 dxy1 = sk_FragCoord.xy - %s.zw;", rectName);
-            fragBuilder->codeAppend("half2 dxy = max(max(dxy0, dxy1), 0.0);");
+            fragBuilder->codeAppendf("float2 dxy0 = %s.xy - sk_FragCoord.xy;", rectName);
+            fragBuilder->codeAppendf("float2 dxy1 = sk_FragCoord.xy - %s.zw;", rectName);
+            fragBuilder->codeAppend("float2 dxy = max(max(dxy0, dxy1), 0.0);");
             fragBuilder->codeAppendf("half alpha = %s;", clampedCircleDistance.c_str());
             break;
         case CircularRRectEffect::kTopLeft_CornerFlag:
-            fragBuilder->codeAppendf("half2 dxy = max(%s.xy - sk_FragCoord.xy, 0.0);",
+            fragBuilder->codeAppendf("float2 dxy = max(%s.xy - sk_FragCoord.xy, 0.0);",
                                      rectName);
             fragBuilder->codeAppendf("half rightAlpha = clamp(%s.z - sk_FragCoord.x, 0.0, 1.0);",
                                      rectName);
@@ -208,8 +208,8 @@ void GLCircularRRectEffect::emitCode(EmitArgs& args) {
                                      clampedCircleDistance.c_str());
             break;
         case CircularRRectEffect::kTopRight_CornerFlag:
-            fragBuilder->codeAppendf("half2 dxy = max(half2(sk_FragCoord.x - %s.z, "
-                                                           "%s.y - sk_FragCoord.y), 0.0);",
+            fragBuilder->codeAppendf("float2 dxy = max(float2(sk_FragCoord.x - %s.z, "
+                                                             "%s.y - sk_FragCoord.y), 0.0);",
                                      rectName, rectName);
             fragBuilder->codeAppendf("half leftAlpha = clamp(sk_FragCoord.x - %s.x, 0.0, 1.0);",
                                      rectName);
@@ -219,7 +219,7 @@ void GLCircularRRectEffect::emitCode(EmitArgs& args) {
                                      clampedCircleDistance.c_str());
             break;
         case CircularRRectEffect::kBottomRight_CornerFlag:
-            fragBuilder->codeAppendf("half2 dxy = max(sk_FragCoord.xy - %s.zw, 0.0);",
+            fragBuilder->codeAppendf("float2 dxy = max(sk_FragCoord.xy - %s.zw, 0.0);",
                                      rectName);
             fragBuilder->codeAppendf("half leftAlpha = clamp(sk_FragCoord.x - %s.x, 0.0, 1.0);",
                                      rectName);
@@ -229,8 +229,8 @@ void GLCircularRRectEffect::emitCode(EmitArgs& args) {
                                      clampedCircleDistance.c_str());
             break;
         case CircularRRectEffect::kBottomLeft_CornerFlag:
-            fragBuilder->codeAppendf("half2 dxy = max(half2(%s.x - sk_FragCoord.x, sk_FragCoord.y - "
-                                     "%s.w), 0.0);",
+            fragBuilder->codeAppendf("float2 dxy = max(float2(%s.x - sk_FragCoord.x, "
+                                                             "sk_FragCoord.y - %s.w), 0.0);",
                                      rectName, rectName);
             fragBuilder->codeAppendf("half rightAlpha = clamp(%s.z - sk_FragCoord.x, 0.0, 1.0);",
                                      rectName);
@@ -240,36 +240,36 @@ void GLCircularRRectEffect::emitCode(EmitArgs& args) {
                                      clampedCircleDistance.c_str());
             break;
         case CircularRRectEffect::kLeft_CornerFlags:
-            fragBuilder->codeAppendf("half2 dxy0 = %s.xy - sk_FragCoord.xy;", rectName);
-            fragBuilder->codeAppendf("half dy1 = sk_FragCoord.y - %s.w;", rectName);
-            fragBuilder->codeAppend("half2 dxy = max(half2(dxy0.x, max(dxy0.y, dy1)), 0.0);");
+            fragBuilder->codeAppendf("float2 dxy0 = %s.xy - sk_FragCoord.xy;", rectName);
+            fragBuilder->codeAppendf("float dy1 = sk_FragCoord.y - %s.w;", rectName);
+            fragBuilder->codeAppend("float2 dxy = max(float2(dxy0.x, max(dxy0.y, dy1)), 0.0);");
             fragBuilder->codeAppendf("half rightAlpha = clamp(%s.z - sk_FragCoord.x, 0.0, 1.0);",
                                      rectName);
             fragBuilder->codeAppendf("half alpha = rightAlpha * %s;",
                                      clampedCircleDistance.c_str());
             break;
         case CircularRRectEffect::kTop_CornerFlags:
-            fragBuilder->codeAppendf("half2 dxy0 = %s.xy - sk_FragCoord.xy;", rectName);
-            fragBuilder->codeAppendf("half dx1 = sk_FragCoord.x - %s.z;", rectName);
-            fragBuilder->codeAppend("half2 dxy = max(half2(max(dxy0.x, dx1), dxy0.y), 0.0);");
+            fragBuilder->codeAppendf("float2 dxy0 = %s.xy - sk_FragCoord.xy;", rectName);
+            fragBuilder->codeAppendf("float dx1 = sk_FragCoord.x - %s.z;", rectName);
+            fragBuilder->codeAppend("float2 dxy = max(float2(max(dxy0.x, dx1), dxy0.y), 0.0);");
             fragBuilder->codeAppendf("half bottomAlpha = clamp(%s.w - sk_FragCoord.y, 0.0, 1.0);",
                                      rectName);
             fragBuilder->codeAppendf("half alpha = bottomAlpha * %s;",
                                      clampedCircleDistance.c_str());
             break;
         case CircularRRectEffect::kRight_CornerFlags:
-            fragBuilder->codeAppendf("half dy0 = %s.y - sk_FragCoord.y;", rectName);
-            fragBuilder->codeAppendf("half2 dxy1 = sk_FragCoord.xy - %s.zw;", rectName);
-            fragBuilder->codeAppend("half2 dxy = max(half2(dxy1.x, max(dy0, dxy1.y)), 0.0);");
+            fragBuilder->codeAppendf("float dy0 = %s.y - sk_FragCoord.y;", rectName);
+            fragBuilder->codeAppendf("float2 dxy1 = sk_FragCoord.xy - %s.zw;", rectName);
+            fragBuilder->codeAppend("float2 dxy = max(float2(dxy1.x, max(dy0, dxy1.y)), 0.0);");
             fragBuilder->codeAppendf("half leftAlpha = clamp(sk_FragCoord.x - %s.x, 0.0, 1.0);",
                                      rectName);
             fragBuilder->codeAppendf("half alpha = leftAlpha * %s;",
                                      clampedCircleDistance.c_str());
             break;
         case CircularRRectEffect::kBottom_CornerFlags:
-            fragBuilder->codeAppendf("half dx0 = %s.x - sk_FragCoord.x;", rectName);
-            fragBuilder->codeAppendf("half2 dxy1 = sk_FragCoord.xy - %s.zw;", rectName);
-            fragBuilder->codeAppend("half2 dxy = max(half2(max(dx0, dxy1.x), dxy1.y), 0.0);");
+            fragBuilder->codeAppendf("float dx0 = %s.x - sk_FragCoord.x;", rectName);
+            fragBuilder->codeAppendf("float2 dxy1 = sk_FragCoord.xy - %s.zw;", rectName);
+            fragBuilder->codeAppend("float2 dxy = max(float2(max(dx0, dxy1.x), dxy1.y), 0.0);");
             fragBuilder->codeAppendf("half topAlpha = clamp(sk_FragCoord.y - %s.y, 0.0, 1.0);",
                                      rectName);
             fragBuilder->codeAppendf("half alpha = topAlpha * %s;",
@@ -523,14 +523,14 @@ void GLEllipticalRRectEffect::emitCode(EmitArgs& args) {
     // The code below is a simplified version of the above that performs maxs on the vector
     // components before computing distances and alpha values so that only one distance computation
     // need be computed to determine the min alpha.
-    fragBuilder->codeAppendf("half2 dxy0 = %s.xy - sk_FragCoord.xy;", rectName);
-    fragBuilder->codeAppendf("half2 dxy1 = sk_FragCoord.xy - %s.zw;", rectName);
+    fragBuilder->codeAppendf("float2 dxy0 = %s.xy - sk_FragCoord.xy;", rectName);
+    fragBuilder->codeAppendf("float2 dxy1 = sk_FragCoord.xy - %s.zw;", rectName);
 
-    // If we're on a device with a "real" mediump then we'll do the distance computation in a space
+    // If we're on a device where float != fp32 then we'll do the distance computation in a space
     // that is normalized by the largest radius. The scale uniform will be scale, 1/scale. The
     // radii uniform values are already in this normalized space.
     const char* scaleName = nullptr;
-    if (args.fShaderCaps->floatPrecisionVaries()) {
+    if (!args.fShaderCaps->floatIs32Bits()) {
         fScaleUniform = uniformHandler->addUniform(kFragment_GrShaderFlag, kHalf2_GrSLType, "scale",
                                                    &scaleName);
     }
@@ -543,12 +543,12 @@ void GLEllipticalRRectEffect::emitCode(EmitArgs& args) {
                                                              kHalf2_GrSLType,
                                                              "invRadiiXY",
                                                              &invRadiiXYSqdName);
-            fragBuilder->codeAppend("half2 dxy = max(max(dxy0, dxy1), 0.0);");
+            fragBuilder->codeAppend("float2 dxy = max(max(dxy0, dxy1), 0.0);");
             if (scaleName) {
                 fragBuilder->codeAppendf("dxy *= %s.y;", scaleName);
             }
             // Z is the x/y offsets divided by squared radii.
-            fragBuilder->codeAppendf("half2 Z = dxy * %s.xy;", invRadiiXYSqdName);
+            fragBuilder->codeAppendf("float2 Z = dxy * %s.xy;", invRadiiXYSqdName);
             break;
         }
         case SkRRect::kNinePatch_Type: {
@@ -561,11 +561,11 @@ void GLEllipticalRRectEffect::emitCode(EmitArgs& args) {
                 fragBuilder->codeAppendf("dxy0 *= %s.y;", scaleName);
                 fragBuilder->codeAppendf("dxy1 *= %s.y;", scaleName);
             }
-            fragBuilder->codeAppend("half2 dxy = max(max(dxy0, dxy1), 0.0);");
+            fragBuilder->codeAppend("float2 dxy = max(max(dxy0, dxy1), 0.0);");
             // Z is the x/y offsets divided by squared radii. We only care about the (at most) one
             // corner where both the x and y offsets are positive, hence the maxes. (The inverse
             // squared radii will always be positive.)
-            fragBuilder->codeAppendf("half2 Z = max(max(dxy0 * %s.xy, dxy1 * %s.zw), 0.0);",
+            fragBuilder->codeAppendf("float2 Z = max(max(dxy0 * %s.xy, dxy1 * %s.zw), 0.0);",
                                      invRadiiLTRBSqdName, invRadiiLTRBSqdName);
 
             break;
@@ -574,12 +574,12 @@ void GLEllipticalRRectEffect::emitCode(EmitArgs& args) {
             SK_ABORT("RRect should always be simple or nine-patch.");
     }
     // implicit is the evaluation of (x/a)^2 + (y/b)^2 - 1.
-    fragBuilder->codeAppend("half implicit = dot(Z, dxy) - 1.0;");
+    fragBuilder->codeAppend("float implicit = dot(Z, dxy) - 1.0;");
     // grad_dot is the squared length of the gradient of the implicit.
-    fragBuilder->codeAppend("half grad_dot = 4.0 * dot(Z, Z);");
+    fragBuilder->codeAppend("float grad_dot = 4.0 * dot(Z, Z);");
     // avoid calling inversesqrt on zero.
     fragBuilder->codeAppend("grad_dot = max(grad_dot, 1.0e-4);");
-    fragBuilder->codeAppend("half approx_dist = implicit * inversesqrt(grad_dot);");
+    fragBuilder->codeAppend("float approx_dist = implicit * inversesqrt(grad_dot);");
     if (scaleName) {
         fragBuilder->codeAppendf("approx_dist *= %s.x;", scaleName);
     }
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index fe9bce8528..0c185e4a78 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -291,7 +291,7 @@ void GrGLCaps::init(const GrContextOptions& contextOptions,
     **************************************************************************/
 
     // This must be called after fCoreProfile is set on the GrGLCaps
-    this->initGLSL(ctxInfo);
+    this->initGLSL(ctxInfo, gli);
     GrShaderCaps* shaderCaps = fShaderCaps.get();
 
     shaderCaps->fPathRenderingSupport = this->hasPathRenderingSupport(ctxInfo, gli);
@@ -634,8 +634,6 @@ void GrGLCaps::init(const GrContextOptions& contextOptions,
         fDrawRangeElementsSupport = version >= GR_GL_VER(3,0);
     }
 
-    this->initShaderPrecisionTable(ctxInfo, gli, shaderCaps);
-
     if (kGL_GrGLStandard == standard) {
         if ((version >= GR_GL_VER(4, 0) || ctxInfo.hasExtension("GL_ARB_sample_shading")) &&
             ctxInfo.vendor() != kIntel_GrGLVendor) {
@@ -760,7 +758,27 @@ const char* get_glsl_version_decl_string(GrGLStandard standard, GrGLSLGeneration
     return "<no version>";
 }
 
-void GrGLCaps::initGLSL(const GrGLContextInfo& ctxInfo) {
+bool is_float_fp32(const GrGLContextInfo& ctxInfo, const GrGLInterface* gli, GrGLenum precision) {
+    if (kGLES_GrGLStandard != ctxInfo.standard() &&
+        ctxInfo.version() < GR_GL_VER(4,1) &&
+        !ctxInfo.hasExtension("GL_ARB_ES2_compatibility")) {
+        // We're on a desktop GL that doesn't have precision info. Assume they're all 32bit float.
+        return true;
+    }
+    // glGetShaderPrecisionFormat doesn't accept GL_GEOMETRY_SHADER as a shader type. Hopefully the
+    // geometry shaders don't have lower precision than vertex and fragment.
+    for (GrGLenum shader : {GR_GL_FRAGMENT_SHADER, GR_GL_VERTEX_SHADER}) {
+        GrGLint range[2];
+        GrGLint bits;
+        GR_GL_GetShaderPrecisionFormat(gli, shader, precision, range, &bits);
+        if (range[0] < 127 || range[1] < 127 || bits < 23) {
+            return false;
+        }
+    }
+    return true;
+}
+
+void GrGLCaps::initGLSL(const GrGLContextInfo& ctxInfo, const GrGLInterface* gli) {
     GrGLStandard standard = ctxInfo.standard();
     GrGLVersion version = ctxInfo.version();
 
@@ -937,6 +955,9 @@ void GrGLCaps::initGLSL(const GrGLContextInfo& ctxInfo) {
         shaderCaps->fVertexIDSupport = ctxInfo.glslGeneration() >= k330_GrGLSLGeneration;
     }
 
+    shaderCaps->fFloatIs32Bits = is_float_fp32(ctxInfo, gli, GR_GL_HIGH_FLOAT);
+    shaderCaps->fHalfIs32Bits = is_float_fp32(ctxInfo, gli, GR_GL_MEDIUM_FLOAT);
+
     if (kTegra3_GrGLRenderer == ctxInfo.renderer()) {
         // The Tegra3 compiler will sometimes never return if we have min(abs(x), 1.0),
         // so we must do the abs first in a separate expression.
@@ -1408,92 +1429,6 @@ void GrGLCaps::onDumpJSON(SkJSONWriter* writer) const {
     writer->endObject();
 }
 
-static GrGLenum precision_to_gl_float_type(GrSLPrecision p) {
-    switch (p) {
-    case kLow_GrSLPrecision:
-        return GR_GL_LOW_FLOAT;
-    case kMedium_GrSLPrecision:
-        return GR_GL_MEDIUM_FLOAT;
-    case kHigh_GrSLPrecision:
-        return GR_GL_HIGH_FLOAT;
-    default:
-        SK_ABORT("Unexpected precision type.");
-        return -1;
-    }
-}
-
-static GrGLenum shader_type_to_gl_shader(GrShaderType type) {
-    switch (type) {
-    case kVertex_GrShaderType:
-        return GR_GL_VERTEX_SHADER;
-    case kGeometry_GrShaderType:
-        return GR_GL_GEOMETRY_SHADER;
-    case kFragment_GrShaderType:
-        return GR_GL_FRAGMENT_SHADER;
-    }
-    SK_ABORT("Unknown shader type.");
-    return -1;
-}
-
-void GrGLCaps::initShaderPrecisionTable(const GrGLContextInfo& ctxInfo,
-                                        const GrGLInterface* intf,
-                                        GrShaderCaps* shaderCaps) {
-    if (kGLES_GrGLStandard == ctxInfo.standard() || ctxInfo.version() >= GR_GL_VER(4, 1) ||
-        ctxInfo.hasExtension("GL_ARB_ES2_compatibility")) {
-        for (int s = 0; s < kGrShaderTypeCount; ++s) {
-            if (kGeometry_GrShaderType != s) {
-                GrShaderType shaderType = static_cast<GrShaderType>(s);
-                GrGLenum glShader = shader_type_to_gl_shader(shaderType);
-                GrShaderCaps::PrecisionInfo* first = nullptr;
-                shaderCaps->fShaderPrecisionVaries = false;
-                for (int p = 0; p < kGrSLPrecisionCount; ++p) {
-                    GrSLPrecision precision = static_cast<GrSLPrecision>(p);
-                    GrGLenum glPrecision = precision_to_gl_float_type(precision);
-                    GrGLint range[2];
-                    GrGLint bits;
-                    GR_GL_GetShaderPrecisionFormat(intf, glShader, glPrecision, range, &bits);
-                    if (bits) {
-                        shaderCaps->fFloatPrecisions[s][p].fLogRangeLow = range[0];
-                        shaderCaps->fFloatPrecisions[s][p].fLogRangeHigh = range[1];
-                        shaderCaps->fFloatPrecisions[s][p].fBits = bits;
-                        if (!first) {
-                            first = &shaderCaps->fFloatPrecisions[s][p];
-                        }
-                        else if (!shaderCaps->fShaderPrecisionVaries) {
-                            shaderCaps->fShaderPrecisionVaries =
-                                                     (*first != shaderCaps->fFloatPrecisions[s][p]);
-                        }
-                    }
-                }
-            }
-        }
-    }
-    else {
-        // We're on a desktop GL that doesn't have precision info. Assume they're all 32bit float.
-        shaderCaps->fShaderPrecisionVaries = false;
-        for (int s = 0; s < kGrShaderTypeCount; ++s) {
-            if (kGeometry_GrShaderType != s) {
-                for (int p = 0; p < kGrSLPrecisionCount; ++p) {
-                    shaderCaps->fFloatPrecisions[s][p].fLogRangeLow = 127;
-                    shaderCaps->fFloatPrecisions[s][p].fLogRangeHigh = 127;
-                    shaderCaps->fFloatPrecisions[s][p].fBits = 23;
-                }
-            }
-        }
-    }
-    // GetShaderPrecisionFormat doesn't accept GL_GEOMETRY_SHADER as a shader type. Assume they're
-    // the same as the vertex shader. Only fragment shaders were ever allowed to omit support for
-    // highp. GS was added after GetShaderPrecisionFormat was added to the list of features that
-    // are recommended against.
-    if (shaderCaps->fGeometryShaderSupport) {
-        for (int p = 0; p < kGrSLPrecisionCount; ++p) {
-            shaderCaps->fFloatPrecisions[kGeometry_GrShaderType][p] =
-                                               shaderCaps->fFloatPrecisions[kVertex_GrShaderType][p];
-        }
-    }
-    shaderCaps->initSamplerPrecisionTable();
-}
-
 bool GrGLCaps::bgraIsInternalFormat() const {
     return fConfigTable[kBGRA_8888_GrPixelConfig].fFormats.fBaseInternalFormat == GR_GL_BGRA;
 }
diff --git a/src/gpu/gl/GrGLCaps.h b/src/gpu/gl/GrGLCaps.h
index 923b3f416d..3a50e8a393 100644
--- a/src/gpu/gl/GrGLCaps.h
+++ b/src/gpu/gl/GrGLCaps.h
@@ -428,7 +428,7 @@ private:
                            GrGLenum* externalType) const;
 
     void init(const GrContextOptions&, const GrGLContextInfo&, const GrGLInterface*);
-    void initGLSL(const GrGLContextInfo&);
+    void initGLSL(const GrGLContextInfo&, const GrGLInterface*);
     bool hasPathRenderingSupport(const GrGLContextInfo&, const GrGLInterface*);
 
     void onApplyOptionsOverrides(const GrContextOptions& options) override;
@@ -441,8 +441,6 @@ private:
     void initConfigTable(const GrContextOptions&, const GrGLContextInfo&, const GrGLInterface*,
                          GrShaderCaps*);
 
-    void initShaderPrecisionTable(const GrGLContextInfo&, const GrGLInterface*, GrShaderCaps*);
-
     GrGLStandard fStandard;
 
     SkTArray<StencilFormat, true> fStencilFormats;
diff --git a/src/gpu/glsl/GrGLSLProgramBuilder.cpp b/src/gpu/glsl/GrGLSLProgramBuilder.cpp
index 6f8d1be736..118b904540 100644
--- a/src/gpu/glsl/GrGLSLProgramBuilder.cpp
+++ b/src/gpu/glsl/GrGLSLProgramBuilder.cpp
@@ -303,7 +303,7 @@ GrGLSLProgramBuilder::SamplerHandle GrGLSLProgramBuilder::emitSampler(GrSLType s
                                                                       const char* name,
                                                                       GrShaderFlags visibility) {
     this->updateSamplerCounts(visibility);
-    GrSLPrecision precision = this->shaderCaps()->samplerPrecision(config, visibility);
+    GrSLPrecision precision = GrSLSamplerPrecision(config);
     GrSwizzle swizzle = this->shaderCaps()->configTextureSwizzle(config);
     return this->uniformHandler()->addSampler(visibility, swizzle, samplerType, precision, name);
 }
@@ -311,7 +311,7 @@ GrGLSLProgramBuilder::SamplerHandle GrGLSLProgramBuilder::emitSampler(GrSLType s
 GrGLSLProgramBuilder::TexelBufferHandle GrGLSLProgramBuilder::emitTexelBuffer(
         GrPixelConfig config, const char* name, GrShaderFlags visibility) {
     this->updateSamplerCounts(visibility);
-    GrSLPrecision precision = this->shaderCaps()->samplerPrecision(config, visibility);
+    GrSLPrecision precision = GrSLSamplerPrecision(config);
     return this->uniformHandler()->addTexelBuffer(visibility, precision, name);
 }
 
diff --git a/src/gpu/mtl/GrMtlCaps.mm b/src/gpu/mtl/GrMtlCaps.mm
index d431f0a1e1..2354b85e64 100644
--- a/src/gpu/mtl/GrMtlCaps.mm
+++ b/src/gpu/mtl/GrMtlCaps.mm
@@ -229,21 +229,10 @@ void GrMtlCaps::initShaderCaps() {
     shaderCaps->fTexelFetchSupport = false;
     shaderCaps->fVertexIDSupport = false;
     shaderCaps->fImageLoadStoreSupport = false;
-    shaderCaps->fShaderPrecisionVaries = false; // ???
 
-    // Metal uses IEEE float and half floats so using those values here.
-    for (int s = 0; s < kGrShaderTypeCount; ++s) {
-        auto& highp = shaderCaps->fFloatPrecisions[s][kHigh_GrSLPrecision];
-        highp.fLogRangeLow = highp.fLogRangeHigh = 127;
-        highp.fBits = 23;
-
-        auto& mediump = shaderCaps->fFloatPrecisions[s][kMedium_GrSLPrecision];
-        mediump.fLogRangeLow = mediump.fLogRangeHigh = 15;
-        mediump.fBits = 10;
-
-        shaderCaps->fFloatPrecisions[s][kLow_GrSLPrecision] = mediump;
-    }
-    shaderCaps->initSamplerPrecisionTable();
+    // Metal uses IEEE float and half floats so assuming those values here.
+    shaderCaps->fFloatIs32Bits = true;
+    shaderCaps->fHalfIs32Bits = false;
 
     shaderCaps->fMaxVertexSamplers =
     shaderCaps->fMaxFragmentSamplers = 16;
diff --git a/src/gpu/vk/GrVkCaps.cpp b/src/gpu/vk/GrVkCaps.cpp
index 2b24205af8..f5c4b342ed 100644
--- a/src/gpu/vk/GrVkCaps.cpp
+++ b/src/gpu/vk/GrVkCaps.cpp
@@ -259,19 +259,8 @@ void GrVkCaps::initShaderCaps(const VkPhysicalDeviceProperties& properties, uint
     shaderCaps->fVertexIDSupport = true;
 
     // Assume the minimum precisions mandated by the SPIR-V spec.
-    shaderCaps->fShaderPrecisionVaries = true;
-    for (int s = 0; s < kGrShaderTypeCount; ++s) {
-        auto& highp = shaderCaps->fFloatPrecisions[s][kHigh_GrSLPrecision];
-        highp.fLogRangeLow = highp.fLogRangeHigh = 127;
-        highp.fBits = 23;
-
-        auto& mediump = shaderCaps->fFloatPrecisions[s][kMedium_GrSLPrecision];
-        mediump.fLogRangeLow = mediump.fLogRangeHigh = 14;
-        mediump.fBits = 10;
-
-        shaderCaps->fFloatPrecisions[s][kLow_GrSLPrecision] = mediump;
-    }
-    shaderCaps->initSamplerPrecisionTable();
+    shaderCaps->fFloatIs32Bits = true;
+    shaderCaps->fHalfIs32Bits = false;
 
     shaderCaps->fMaxVertexSamplers =
     shaderCaps->fMaxGeometrySamplers =