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[Fix, Test] (ShaderTranspiler): carry r11f_g11f_b10f storage images in rgba16f instead of losing the stage

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swung0x48
2026-08-21 21:21:54 -04:00
parent ece9491d4b
commit 9bd125aeec
3 changed files with 148 additions and 28 deletions
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MobileGL/MG_Test/ShaderTranspiler/WidenImageFormatsTest.cpp
+95 -13
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@@ -14,10 +14,10 @@
// and every draw with the program silently renders nothing while GL_LINK_STATUS still says TRUE.
//
// What has to hold is the emulation's exactness, in three parts at once: the DECLARED format must
// become the core carrier of the same per-channel width, every imageStore through it must have its
// surplus components replaced by GL's own (0.., 1) so the carrier's extra channels never hold
// anything GL has not defined, and every imageLoad must come back masked the same way. A module
// that declares only core formats - or one of the nine formats with no exact carrier - must come
// become a core carrier that loses nothing, every imageStore through it must have its surplus
// components replaced by GL's own (0.., 1) so the carrier's extra channels never hold anything GL
// has not defined, and every imageLoad must come back masked the same way. A module that declares
// only core formats - or one of the eight formats with no lossless carrier at all - must come
// out untouched, because widening those would be an approximation rather than an emulation. Real
// GLSL through the same glslang path the backends use, for the same reason
// ClampMultisampleFetchTest.cpp does it: what matters is what glslang actually emits.
@@ -229,9 +229,23 @@ void main() {
}
)";
// rg16 is one of the NINE with no core carrier of the same per-channel width. Widening it
// would change the quantisation an application sees, so it must be left alone and keep the
// honest "no GLSL ES spelling" diagnostic instead.
// r11f_g11f_b10f: THREE float channels in a packed 32-bit word, and the only format the four
// CTS allFormats/allTargets walkers still aborted on after the channel widening landed - it
// has no core carrier of the same per-channel width, so it took rgba16f, whose 5-bit exponent
// and longer mantissa represent every 11f and 10f value exactly.
const char* const kR11fG11fB10fLoadStore = R"(#version 430 core
layout(r11f_g11f_b10f, binding = 0) uniform image2D img;
out vec4 fragColor;
void main() {
vec4 texel = imageLoad(img, ivec2(gl_FragCoord.xy));
imageStore(img, ivec2(gl_FragCoord.xy), vec4(1.0, 2.0, 3.0, 4.0));
fragColor = texel;
}
)";
// rg16 is one of the EIGHT with no core carrier at all - core ESSL has no 16-bit normalized
// format, so every candidate loses range or changes the component type the texture presents.
// It must be left alone and keep the honest "no GLSL ES spelling" diagnostic instead.
const char* const kRg16LoadStore = R"(#version 430 core
layout(rg16, binding = 0) uniform image2D img;
out vec4 fragColor;
@@ -247,7 +261,7 @@ void main() {
// the shader rewrite, the ES texture storage and the glBindImageTexture argument. If it drifts
// the three stop agreeing, and a narrow texture read through a wide image goes out of bounds
// silently on every driver tested.
TEST(WidenImageFormats, SeventeenNonCoreFormatsHaveAnExactSameWidthCarrier) {
TEST(WidenImageFormats, EighteenNonCoreFormatsHaveALosslessCoreCarrier) {
struct Case {
Uint requested;
Uint carrier;
@@ -272,6 +286,10 @@ TEST(WidenImageFormats, SeventeenNonCoreFormatsHaveAnExactSameWidthCarrier) {
{0x8234, 0x8D76, 1, "GL_R16UI -> GL_RGBA16UI"},
{0x8238, 0x8D7C, 2, "GL_RG8UI -> GL_RGBA8UI"},
{0x8232, 0x8D7C, 1, "GL_R8UI -> GL_RGBA8UI"},
// The one entry that is a re-encoding rather than a channel widening: 11f is e5m6 and 10f
// is e5m5 against a half's s1e5m10, so the carrier is still lossless - and three channels,
// so the mask has to pin only alpha.
{0x8C3A, 0x881A, 3, "GL_R11F_G11F_B10F -> GL_RGBA16F"},
};
for (const Case& testCase : cases) {
EXPECT_EQ(ShaderCompiler::WidenedCoreEsslImageFormat(testCase.requested), testCase.carrier)
@@ -287,7 +305,7 @@ TEST(WidenImageFormats, SeventeenNonCoreFormatsHaveAnExactSameWidthCarrier) {
}
}
TEST(WidenImageFormats, CoreFormatsAndTheNineWithoutAnExactCarrierAreRefused) {
TEST(WidenImageFormats, CoreFormatsAndTheEightWithoutALosslessCarrierAreRefused) {
// The thirteen GLSL ES already has: nothing to carry.
for (const Uint coreFormat : {0x8814u /*RGBA32F*/, 0x881Au /*RGBA16F*/, 0x822Eu /*R32F*/,
0x8058u /*RGBA8*/, 0x8F97u /*RGBA8_SNORM*/, 0x8D82u /*RGBA32I*/,
@@ -297,10 +315,12 @@ TEST(WidenImageFormats, CoreFormatsAndTheNineWithoutAnExactCarrierAreRefused) {
EXPECT_EQ(ShaderCompiler::WidenedCoreEsslImageFormat(coreFormat), 0u)
<< "core format 0x" << std::hex << coreFormat;
}
// The nine with no core format of the same per-channel width. Carrying these would be an
// approximation - a different quantisation, or a different numeric domain for anything that
// samples the same texture - so they are deliberately left to the honest diagnostic.
for (const Uint hardFormat : {0x8C3Au /*R11F_G11F_B10F*/, 0x8059u /*RGB10_A2*/,
// The eight with no LOSSLESS core carrier: core ESSL has no 16-bit normalized format and no
// 10-bit one, so every candidate for these either loses range or changes the component type
// the texture presents to anything that samples it. Deliberately left to the honest
// diagnostic. r11f_g11f_b10f is NOT among them - rgba16f holds every value it can, so it is
// carried above.
for (const Uint hardFormat : {0x8059u /*RGB10_A2*/,
0x906Fu /*RGB10_A2UI*/, 0x805Bu /*RGBA16*/, 0x822Cu /*RG16*/,
0x822Au /*R16*/, 0x8F9Bu /*RGBA16_SNORM*/, 0x8F99u /*RG16_SNORM*/,
0x8F98u /*R16_SNORM*/}) {
@@ -357,6 +377,68 @@ TEST(WidenImageFormats, TwoChannelFloatImageBecomesRgba32fWithBothAccessesMasked
<< "the mask must be a separate value, or it would feed itself";
}
// The three-channel case, which no format exercised before r11f_g11f_b10f was carried: only ALPHA
// is surplus, so the mask must take r, g and b from the texel and nothing but the fourth component
// from the (0, 0, 0, 1) constant. A mask that zeroed blue here - the shape a two-channel format
// wants - would silently drop the third channel of every store.
TEST(WidenImageFormats, ThreeChannelPackedFloatImageBecomesRgba16fWithOnlyAlphaPinned) {
const Vector<Uint32> spirv = CompileFragment(kR11fG11fB10fLoadStore);
ASSERT_FALSE(spirv.empty());
ASSERT_TRUE(ShaderCompiler::DeclaresWidenableImageFormat(spirv));
const auto beforeTypes = CollectStorageImageTypes(spirv);
ASSERT_EQ(beforeTypes.size(), 1u);
EXPECT_EQ(beforeTypes.front().format, static_cast<Uint32>(spv::ImageFormat::R11fG11fB10f));
Vector<Uint32> widened;
ASSERT_TRUE(ShaderCompiler::WidenImageFormatsForEssl(spirv, widened, /*onlyFormatsSpirvCrossRefusesToPrint=*/false,
/*enableSpirvValidation=*/true));
ASSERT_FALSE(widened.empty());
EXPECT_TRUE(Validates(widened));
EXPECT_FALSE(ShaderCompiler::DeclaresWidenableImageFormat(widened));
const auto afterTypes = CollectStorageImageTypes(widened);
ASSERT_EQ(afterTypes.size(), 1u);
EXPECT_EQ(afterTypes.front().format, static_cast<Uint32>(spv::ImageFormat::Rgba16f));
const auto shuffles = CollectVectorShuffles(widened);
const auto texelIds = CollectImageWriteTexelIds(widened);
ASSERT_EQ(texelIds.size(), 1u);
const VectorShuffle* storeMask = FindShuffleWithResult(shuffles, texelIds.front());
ASSERT_NE(storeMask, nullptr) << "the imageStore texel is not a masked value";
EXPECT_TRUE(HasComponents(*storeMask, {0u, 1u, 2u, 7u}))
<< "expected (r, g, b, 1) - components 0, 1 and 2 of the texel, then 3 of (0,0,0,1)";
const auto readIds = CollectImageReadResultIds(widened);
ASSERT_EQ(readIds.size(), 1u);
const VectorShuffle* loadMask = FindShuffleOver(shuffles, readIds.front());
ASSERT_NE(loadMask, nullptr) << "the imageLoad result is consumed unmasked";
EXPECT_TRUE(HasComponents(*loadMask, {0u, 1u, 2u, 7u}));
}
// ...and the same module through the emitter, which is where the failure actually showed: ESSL has
// no `r11f_g11f_b10f` token, SPIRV-Cross throws for it, and the throw took every image uniform
// declared in the same stage with it.
TEST(WidenImageFormats, PackedFloatImageOnlyReachesEsslThroughTheCarrier) {
const Vector<Uint32> spirv = CompileFragment(kR11fG11fB10fLoadStore);
ASSERT_FALSE(spirv.empty());
const EsslAttempt before = EmitEssl(spirv);
EXPECT_FALSE(before.succeeded)
<< "SPIRV-Cross printed r11f_g11f_b10f for an ES target; the widening's premise has "
"changed:\n"
<< before.text;
Vector<Uint32> widened;
ASSERT_TRUE(ShaderCompiler::WidenImageFormatsForEssl(spirv, widened, /*onlyFormatsSpirvCrossRefusesToPrint=*/false,
/*enableSpirvValidation=*/true));
const EsslAttempt after = EmitEssl(widened);
ASSERT_TRUE(after.succeeded) << after.error;
EXPECT_NE(after.text.find("rgba16f"), String::npos) << after.text;
EXPECT_EQ(after.text.find("r11f_g11f_b10f"), String::npos) << after.text;
}
TEST(WidenImageFormats, SingleChannelUnsignedImageBecomesRgba8uiWithBothAccessesMasked) {
const Vector<Uint32> spirv = CompileFragment(kR8uiLoadStore);
ASSERT_FALSE(spirv.empty());
MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/WidenImageFormatsPass.cpp
+36 -9
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@@ -50,16 +50,40 @@ namespace MobileGL {
constexpr uint32_t kImageAccessImageOperand = 0;
constexpr uint32_t kImageWriteTexelOperand = 2;
// The exact carrier of a non-core image format: the core GLSL ES format with the
// SAME component type and the SAME per-channel width, differing only in channel
// count. `channels` is what the original format really has, which is what every
// access through the carrier is masked back to.
// The carrier of a non-core image format: a core GLSL ES format that represents
// every value the original can hold, WITHOUT LOSS. `channels` is what the original
// format really has, which is what every access through the carrier is masked back
// to.
//
// Only formats that widen EXACTLY appear here. r11f_g11f_b10f, rgb10_a2,
// rgb10_a2ui, rgba16, rg16, r16, rgba16_snorm, rg16_snorm and r16_snorm have no
// same-width core carrier - every candidate is either lossy or changes the numeric
// domain a sampler would read - and are deliberately absent, so they keep the
// honest "no GLSL ES spelling" diagnostic rather than a silent approximation.
// Almost every entry is a pure CHANNEL widening - same component type, same
// per-channel width, more channels (rg32f -> rgba32f) - and for those the carrier
// is bit-exact: the storage holds the identical encoding, only wider.
//
// r11f_g11f_b10f is the one entry that is not. It has no same-width core carrier,
// so it takes rgba16f, and the two encodings differ. What matters is that the
// carrier is still LOSSLESS: an 11-bit float is e5m6 and a 10-bit float is e5m5,
// while a half is s1e5m10 - the SAME 5-bit exponent with a strictly longer
// mantissa - so every value the packed format can represent has an exact half.
// Nothing an application stores is rounded away.
//
// What DOES change is the reverse direction: the carrier can hold values the
// packed format could not - negatives (11f and 10f are unsigned), and mantissa
// bits finer than the 6 and 5 the format quantises to - so a value written through
// the image and then SAMPLED comes back on half's grid rather than the packed
// format's. That is a strictly finer grid, never a lossy one, and it is measured
// against the alternative, which is not a more faithful quantisation but no
// program at all: `layout(r11f_g11f_b10f)` has no ESSL spelling, SPIRV-Cross
// throws for it, and the stage - with every other image uniform declared beside it
// - is lost (KHR-GL43.shader_image_load_store.basic-allFormats-*, which fail on
// this format alone, and multiple-uniforms, where one such declaration killed a
// program holding eight images).
//
// The remaining eight - rgb10_a2, rgb10_a2ui, rgba16, rg16, r16, rgba16_snorm,
// rg16_snorm and r16_snorm - stay absent, and for a stronger reason than
// quantisation: core ESSL has no 16-bit normalized format at all and no 10-bit
// one, so every candidate carrier for them either loses range or changes the
// component TYPE the texture presents. They keep the honest "no GLSL ES spelling"
// diagnostic rather than a silent approximation.
struct ImageFormatWidening {
spv::ImageFormat Carrier = spv::ImageFormat::Unknown;
uint32_t Channels = 0;
@@ -73,6 +97,9 @@ namespace MobileGL {
case spv::ImageFormat::Rg32f: return {spv::ImageFormat::Rgba32f, 2};
case spv::ImageFormat::Rg16f: return {spv::ImageFormat::Rgba16f, 2};
case spv::ImageFormat::R16f: return {spv::ImageFormat::Rgba16f, 1};
// Not a channel widening but a lossless re-encoding - see above. Three
// channels, so the fourth reads as the 1 GL defines for a format without one.
case spv::ImageFormat::R11fG11fB10f: return {spv::ImageFormat::Rgba16f, 3};
// Unsigned normalized.
case spv::ImageFormat::Rg8: return {spv::ImageFormat::Rgba8, 2};
case spv::ImageFormat::R8: return {spv::ImageFormat::Rgba8, 1};
MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/WidenImageFormatsPass.h
+17 -6
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@@ -54,12 +54,23 @@ namespace MobileGL {
// alone survives storage this shader never wrote (glTexStorage with no upload, whose
// surplus channels are undefined).
//
// The other NINE (r11f_g11f_b10f, rgb10_a2, rgb10_a2ui, rgba16, rg16, r16,
// rgba16_snorm, rg16_snorm, r16_snorm) have NO same-width core carrier and are
// deliberately NOT widened here: every carrier for them is either lossy or changes the
// numeric domain of the texture a `sampler2D` would read from it. They keep the honest
// "no GLSL ES spelling" diagnostic instead of silently changing an application's
// quantisation behaviour.
// r11f_g11f_b10f has no same-width core carrier either, and takes rgba16f anyway,
// because that carrier is still LOSSLESS: 11f is e5m6 and 10f is e5m5 against a half's
// s1e5m10 - the SAME 5-bit exponent with a strictly longer mantissa - so every value
// the packed format can hold has an exact half. Only the reverse direction differs
// (the carrier also holds negatives, which 11f and 10f cannot sign, and mantissa bits
// finer than the 6 and 5 they quantise to, so a value written through the image and
// then SAMPLED lands on half's grid rather than the packed format's). That is measured
// against the alternative, which is not a truer quantisation but no program at all:
// the SPIRV-Cross throw takes the whole stage, every image uniform declared beside it
// included.
//
// The other EIGHT (rgb10_a2, rgb10_a2ui, rgba16, rg16, r16, rgba16_snorm, rg16_snorm,
// r16_snorm) are deliberately NOT widened here: core ESSL has no 16-bit normalized
// format at all and no 10-bit one, so every carrier for them either loses range or
// changes the component TYPE the texture a `sampler2D` would read presents. They keep
// the honest "no GLSL ES spelling" diagnostic instead of silently changing an
// application's numeric domain.
//
// MUST MOVE WITH THE OTHER TWO LAYERS. The widening is not a shader-local rewrite: the
// ES texture behind the image has to be allocated in the carrier format too, and