Implement GL_EXT_demote_to_helper_invocation

SPIRV/GLSL.ext.EXT.h

@@ -34,5 +34,6 @@ static const char* const E_SPV_EXT_shader_stencil_export        = "SPV_EXT_shade
 static const char* const E_SPV_EXT_shader_viewport_index_layer  = "SPV_EXT_shader_viewport_index_layer";
 static const char* const E_SPV_EXT_fragment_fully_covered = "SPV_EXT_fragment_fully_covered";
 static const char* const E_SPV_EXT_fragment_invocation_density = "SPV_EXT_fragment_invocation_density";
+static const char* const E_SPV_EXT_demote_to_helper_invocation = "SPV_EXT_demote_to_helper_invocation";
 
 #endif  // #ifndef GLSLextEXT_H

SPIRV/GlslangToSpv.cpp

@@ -3111,6 +3111,12 @@ bool TGlslangToSpvTraverser::visitBranch(glslang::TVisit /* visit */, glslang::T
         builder.clearAccessChain();
         break;
 
+    case glslang::EOpDemote:
+        builder.createNoResultOp(spv::OpDemoteToHelperInvocationEXT);
+        builder.addExtension(spv::E_SPV_EXT_demote_to_helper_invocation);
+        builder.addCapability(spv::CapabilityDemoteToHelperInvocationEXT);
+        break;
+
     default:
         assert(0);
         break;
@@ -7610,6 +7616,13 @@ spv::Id TGlslangToSpvTraverser::createNoArgOperation(glslang::TOperator op, spv:
         builder.createNoResultOp(spv::OpEndInvocationInterlockEXT);
         return 0;
 
+    case glslang::EOpIsHelperInvocation:
+    {
+        std::vector<spv::Id> args; // Dummy arguments
+        spv::Id id = builder.createOp(spv::OpIsHelperInvocationEXT, typeId, args);
+        return id;
+    }
+
     default:
         logger->missingFunctionality("unknown operation with no arguments");
         return 0;

SPIRV/doc.cpp

@@ -1367,6 +1367,8 @@ const char* OpcodeString(int op)
     case OpCooperativeMatrixStoreNV:        return "OpCooperativeMatrixStoreNV";
     case OpCooperativeMatrixMulAddNV:       return "OpCooperativeMatrixMulAddNV";
     case OpCooperativeMatrixLengthNV:       return "OpCooperativeMatrixLengthNV";
+    case OpDemoteToHelperInvocationEXT:     return "OpDemoteToHelperInvocationEXT";
+    case OpIsHelperInvocationEXT:           return "OpIsHelperInvocationEXT";
 
     case OpBeginInvocationInterlockEXT:     return "OpBeginInvocationInterlockEXT";
     case OpEndInvocationInterlockEXT:       return "OpEndInvocationInterlockEXT";
@@ -2784,6 +2786,8 @@ void Parameterize()
     InstructionDesc[OpCooperativeMatrixMulAddNV].operands.push(OperandId, "'C'");
 
     InstructionDesc[OpCooperativeMatrixLengthNV].operands.push(OperandId, "'Type'");
+
+    InstructionDesc[OpDemoteToHelperInvocationEXT].setResultAndType(false, false);
 }
 
 }; // end spv namespace

SPIRV/spirv.hpp

@@ -455,6 +455,7 @@ enum Decoration {
     DecorationHlslCounterBufferGOOGLE = 5634,
     DecorationHlslSemanticGOOGLE = 5635,
     DecorationUserSemantic = 5635,
+    DecorationUserTypeGOOGLE = 5636,
     DecorationMax = 0x7fffffff,
 };
 
@@ -632,7 +633,7 @@ enum MemorySemanticsShift {
     MemorySemanticsOutputMemoryKHRShift = 12,
     MemorySemanticsMakeAvailableKHRShift = 13,
     MemorySemanticsMakeVisibleKHRShift = 14,
-    MemorySemanticsVolatileShift = 15,
+    MemorySemanticsVolatileShift = 15,
     MemorySemanticsMax = 0x7fffffff,
 };
 
@@ -650,8 +651,8 @@ enum MemorySemanticsMask {
     MemorySemanticsImageMemoryMask = 0x00000800,
     MemorySemanticsOutputMemoryKHRMask = 0x00001000,
     MemorySemanticsMakeAvailableKHRMask = 0x00002000,
-    MemorySemanticsMakeVisibleKHRMask = 0x00004000,
-    MemorySemanticsVolatileMask = 0x00008000,
+    MemorySemanticsMakeVisibleKHRMask = 0x00004000,
+    MemorySemanticsVolatileMask = 0x00008000,
 };
 
 enum MemoryAccessShift {
@@ -845,6 +846,7 @@ enum Capability {
     CapabilityFragmentShaderShadingRateInterlockEXT = 5372,
     CapabilityShaderSMBuiltinsNV = 5373,
     CapabilityFragmentShaderPixelInterlockEXT = 5378,
+    CapabilityDemoteToHelperInvocationEXT = 5379,
     CapabilitySubgroupShuffleINTEL = 5568,
     CapabilitySubgroupBufferBlockIOINTEL = 5569,
     CapabilitySubgroupImageBlockIOINTEL = 5570,
@@ -1233,6 +1235,8 @@ enum Op {
     OpCooperativeMatrixLengthNV = 5362,
     OpBeginInvocationInterlockEXT = 5364,
     OpEndInvocationInterlockEXT = 5365,
+    OpDemoteToHelperInvocationEXT = 5380,
+    OpIsHelperInvocationEXT = 5381,
     OpSubgroupShuffleINTEL = 5571,
     OpSubgroupShuffleDownINTEL = 5572,
     OpSubgroupShuffleUpINTEL = 5573,
@@ -1907,6 +1911,8 @@ inline void HasResultAndType(Op opcode, bool *hasResult, bool *hasResultType) {
     case OpSubgroupAvcSicGetInterRawSadsINTEL: *hasResult = true; *hasResultType = true; break;
     case OpBeginInvocationInterlockEXT: *hasResult = false; *hasResultType = false; break;
     case OpEndInvocationInterlockEXT: *hasResult = false; *hasResultType = false; break;
+    case OpDemoteToHelperInvocationEXT: *hasResult = false; *hasResultType = false; break;
+    case OpIsHelperInvocationEXT: *hasResult = true; *hasResultType = true; break;
     }
 }
 #endif /* SPV_ENABLE_UTILITY_CODE */

Test/baseResults/spv.conditionalDemote.frag.out

+spv.conditionalDemote.frag
+Validation failed
+// Module Version 10000
+// Generated by (magic number): 80007
+// Id's are bound by 38
+
+                              Capability Shader
+                              Capability Bad
+                              Extension  "SPV_EXT_demote_to_helper_invocation"
+               1:             ExtInstImport  "GLSL.std.450"
+                              MemoryModel Logical GLSL450
+                              EntryPoint Fragment 4  "main" 17 36
+                              ExecutionMode 4 OriginUpperLeft
+                              Source GLSL 460
+                              SourceExtension  "GL_EXT_demote_to_helper_invocation"
+                              Name 4  "main"
+                              Name 9  "v"
+                              Name 13  "tex"
+                              Name 17  "coord"
+                              Name 33  "x"
+                              Name 36  "o"
+                              Decorate 13(tex) DescriptorSet 0
+                              Decorate 13(tex) Binding 0
+                              Decorate 17(coord) Location 0
+                              Decorate 36(o) Location 0
+               2:             TypeVoid
+               3:             TypeFunction 2
+               6:             TypeFloat 32
+               7:             TypeVector 6(float) 4
+               8:             TypePointer Function 7(fvec4)
+              10:             TypeImage 6(float) 2D sampled format:Unknown
+              11:             TypeSampledImage 10
+              12:             TypePointer UniformConstant 11
+         13(tex):     12(ptr) Variable UniformConstant
+              15:             TypeVector 6(float) 2
+              16:             TypePointer Input 15(fvec2)
+       17(coord):     16(ptr) Variable Input
+              21:    6(float) Constant 1036831949
+              22:    6(float) Constant 1045220557
+              23:    6(float) Constant 1050253722
+              24:    6(float) Constant 1053609165
+              25:    7(fvec4) ConstantComposite 21 22 23 24
+              26:             TypeBool
+              27:             TypeVector 26(bool) 4
+              32:             TypePointer Function 26(bool)
+              35:             TypePointer Output 7(fvec4)
+           36(o):     35(ptr) Variable Output
+         4(main):           2 Function None 3
+               5:             Label
+            9(v):      8(ptr) Variable Function
+           33(x):     32(ptr) Variable Function
+              14:          11 Load 13(tex)
+              18:   15(fvec2) Load 17(coord)
+              19:    7(fvec4) ImageSampleImplicitLod 14 18
+                              Store 9(v) 19
+              20:    7(fvec4) Load 9(v)
+              28:   27(bvec4) FOrdEqual 20 25
+              29:    26(bool) All 28
+                              SelectionMerge 31 None
+                              BranchConditional 29 30 31
+              30:               Label
+                                DemoteToHelperInvocationEXT
+                                Branch 31
+              31:             Label
+              34:    26(bool) IsHelperInvocationEXT
+                              Store 33(x) 34
+              37:    7(fvec4) Load 9(v)
+                              Store 36(o) 37
+                              Return
+                              FunctionEnd

Test/baseResults/spv.demoteDisabled.frag.out

+spv.demoteDisabled.frag
+ERROR: 0:9: 'demote' : undeclared identifier 
+ERROR: 1 compilation errors.  No code generated.
+
+
+SPIR-V is not generated for failed compile or link

Test/spv.conditionalDemote.frag

+#version 460 core
+#extension GL_EXT_demote_to_helper_invocation : enable
+
+layout(set = 0, binding = 0) uniform sampler2D tex;
+layout(location = 0) in vec2 coord;
+layout(location = 0) out vec4 o;
+
+void main (void)
+{
+    vec4 v = texture(tex, coord);
+
+    if (v == vec4(0.1,0.2,0.3,0.4))
+        demote;
+
+    bool x = helperInvocationEXT();
+
+    o = v;
+}

Test/spv.demoteDisabled.frag

+#version 460 core
+
+void main (void)
+{
+    {
+        int demote = 0;
+        demote;
+    }
+    demote;
+}

glslang/Include/intermediate.h

@@ -624,6 +624,8 @@ enum TOperator {
     EOpBeginInvocationInterlock, // Fragment only
     EOpEndInvocationInterlock, // Fragment only
 
+    EOpIsHelperInvocation,
+
     //
     // Branch
     //
@@ -634,6 +636,7 @@ enum TOperator {
     EOpContinue,
     EOpCase,
     EOpDefault,
+    EOpDemote,          // Fragment only
 
     //
     // Constructors

glslang/MachineIndependent/Initialize.cpp

@@ -5034,6 +5034,10 @@ void TBuiltIns::initialize(int version, EProfile profile, const SpvVersion& spvV
         "void beginInvocationInterlockARB(void);"
         "void endInvocationInterlockARB(void);");
 
+    stageBuiltins[EShLangFragment].append(
+        "bool helperInvocationEXT();"
+        "\n");
+
 #ifdef AMD_EXTENSIONS
     // GL_AMD_shader_explicit_vertex_parameter
     if (profile != EEsProfile && version >= 450) {
@@ -8641,6 +8645,8 @@ void TBuiltIns::identifyBuiltIns(int version, EProfile profile, const SpvVersion
             symbolTable.setVariableExtensions("gl_StorageSemanticsImage",   1, &E_GL_KHR_memory_scope_semantics);
             symbolTable.setVariableExtensions("gl_StorageSemanticsOutput",  1, &E_GL_KHR_memory_scope_semantics);
         }
+
+        symbolTable.setFunctionExtensions("helperInvocationEXT",            1, &E_GL_EXT_demote_to_helper_invocation);
         break;
 
     case EShLangCompute:
@@ -9295,6 +9301,8 @@ void TBuiltIns::identifyBuiltIns(int version, EProfile profile, const SpvVersion
     symbolTable.relateToOperator("findLSB",           EOpFindLSB);
     symbolTable.relateToOperator("findMSB",           EOpFindMSB);
 
+    symbolTable.relateToOperator("helperInvocationEXT",  EOpIsHelperInvocation);
+
     if (PureOperatorBuiltins) {
         symbolTable.relateToOperator("imageSize",               EOpImageQuerySize);
         symbolTable.relateToOperator("imageSamples",            EOpImageQuerySamples);

glslang/MachineIndependent/Scan.cpp

@@ -356,6 +356,7 @@ void TScanContext::fillInKeywordMap()
     (*KeywordMap)["default"] =                 DEFAULT;
     (*KeywordMap)["if"] =                      IF;
     (*KeywordMap)["else"] =                    ELSE;
+    (*KeywordMap)["demote"] =                  DEMOTE;
     (*KeywordMap)["discard"] =                 DISCARD;
     (*KeywordMap)["return"] =                  RETURN;
     (*KeywordMap)["void"] =                    VOID;
@@ -1621,6 +1622,12 @@ int TScanContext::tokenizeIdentifier()
             return keyword;
         return identifierOrType();
 
+    case DEMOTE:
+        if (parseContext.extensionTurnedOn(E_GL_EXT_demote_to_helper_invocation))
+            return keyword;
+        else
+            return identifierOrType();
+
     default:
         parseContext.infoSink.info.message(EPrefixInternalError, "Unknown glslang keyword", loc);
         return 0;

glslang/MachineIndependent/Versions.cpp

@@ -211,6 +211,7 @@ void TParseVersions::initializeExtensionBehavior()
     extensionBehavior[E_GL_EXT_fragment_invocation_density]             = EBhDisable;
     extensionBehavior[E_GL_EXT_buffer_reference]                        = EBhDisable;
     extensionBehavior[E_GL_EXT_buffer_reference2]                       = EBhDisable;
+    extensionBehavior[E_GL_EXT_demote_to_helper_invocation]             = EBhDisable;
 
     extensionBehavior[E_GL_EXT_shader_16bit_storage]                    = EBhDisable;
     extensionBehavior[E_GL_EXT_shader_8bit_storage]                     = EBhDisable;
@@ -394,6 +395,7 @@ void TParseVersions::getPreamble(std::string& preamble)
             "#define GL_EXT_fragment_invocation_density 1\n"
             "#define GL_EXT_buffer_reference 1\n"
             "#define GL_EXT_buffer_reference2 1\n"
+            "#define GL_EXT_demote_to_helper_invocation 1\n"
 
             // GL_KHR_shader_subgroup
             "#define GL_KHR_shader_subgroup_basic 1\n"

glslang/MachineIndependent/Versions.h

@@ -173,6 +173,7 @@ const char* const E_GL_EXT_scalar_block_layout              = "GL_EXT_scalar_blo
 const char* const E_GL_EXT_fragment_invocation_density      = "GL_EXT_fragment_invocation_density";
 const char* const E_GL_EXT_buffer_reference                 = "GL_EXT_buffer_reference";
 const char* const E_GL_EXT_buffer_reference2                = "GL_EXT_buffer_reference2";
+const char* const E_GL_EXT_demote_to_helper_invocation      = "GL_EXT_demote_to_helper_invocation";
 
 // Arrays of extensions for the above viewportEXTs duplications
 

glslang/MachineIndependent/glslang.y

@@ -128,7 +128,7 @@ extern int yylex(YYSTYPE*, TParseContext&);
 %token <lex> ATTRIBUTE VARYING
 %token <lex> FLOAT16_T FLOAT FLOAT32_T DOUBLE FLOAT64_T
 %token <lex> CONST BOOL INT UINT INT64_T UINT64_T INT32_T UINT32_T INT16_T UINT16_T INT8_T UINT8_T
-%token <lex> BREAK CONTINUE DO ELSE FOR IF DISCARD RETURN SWITCH CASE DEFAULT SUBROUTINE
+%token <lex> BREAK CONTINUE DO ELSE FOR IF DISCARD RETURN SWITCH CASE DEFAULT SUBROUTINE DEMOTE
 %token <lex> BVEC2 BVEC3 BVEC4
 %token <lex> IVEC2 IVEC3 IVEC4
 %token <lex> UVEC2 UVEC3 UVEC4
@@ -265,7 +265,7 @@ extern int yylex(YYSTYPE*, TParseContext&);
 %type <interm.intermNode> declaration external_declaration
 %type <interm.intermNode> for_init_statement compound_statement_no_new_scope
 %type <interm.nodePair> selection_rest_statement for_rest_statement
-%type <interm.intermNode> iteration_statement iteration_statement_nonattributed jump_statement statement_no_new_scope statement_scoped
+%type <interm.intermNode> iteration_statement iteration_statement_nonattributed jump_statement statement_no_new_scope statement_scoped demote_statement
 %type <interm> single_declaration init_declarator_list
 
 %type <interm> parameter_declaration parameter_declarator parameter_type_specifier
@@ -3416,6 +3416,15 @@ simple_statement
     | case_label            { $$ = $1; }
     | iteration_statement   { $$ = $1; }
     | jump_statement        { $$ = $1; }
+    | demote_statement      { $$ = $1; }
+    ;
+
+demote_statement
+    : DEMOTE SEMICOLON {
+        parseContext.requireStage($1.loc, EShLangFragment, "demote");
+        parseContext.requireExtensions($1.loc, 1, &E_GL_EXT_demote_to_helper_invocation, "demote");
+        $$ = parseContext.intermediate.addBranch(EOpDemote, $1.loc);
+    }
     ;
 
 compound_statement

glslang/MachineIndependent/intermOut.cpp

@@ -1098,6 +1098,8 @@ bool TOutputTraverser::visitAggregate(TVisit /* visit */, TIntermAggregate* node
     case EOpCooperativeMatrixStore:  out.debug << "Store cooperative matrix";  break;
     case EOpCooperativeMatrixMulAdd: out.debug << "MulAdd cooperative matrices"; break;
 
+    case EOpIsHelperInvocation: out.debug << "IsHelperInvocation"; break;
+
     default: out.debug.message(EPrefixError, "Bad aggregation op");
     }
 
@@ -1392,6 +1394,7 @@ bool TOutputTraverser::visitBranch(TVisit /* visit*/, TIntermBranch* node)
     case EOpContinue:  out.debug << "Branch: Continue";       break;
     case EOpReturn:    out.debug << "Branch: Return";         break;
     case EOpCase:      out.debug << "case: ";                 break;
+    case EOpDemote:    out.debug << "Demote";                 break;
     case EOpDefault:   out.debug << "default: ";              break;
     default:               out.debug << "Branch: Unknown Branch"; break;
     }

gtests/Spv.FromFile.cpp

@@ -294,6 +294,7 @@ INSTANTIATE_TEST_CASE_P(
         "spv.bufferhandle9.frag",
         "spv.bufferhandle_Error.frag",
         "spv.builtInXFB.vert",
+        "spv.conditionalDemote.frag",
         "spv.conditionalDiscard.frag",
         "spv.constStruct.vert",
         "spv.constConstruct.vert",
@@ -304,6 +305,7 @@ INSTANTIATE_TEST_CASE_P(
         "spv.dataOut.frag",
         "spv.dataOutIndirect.frag",
         "spv.dataOutIndirect.vert",
+        "spv.demoteDisabled.frag",
         "spv.deepRvalue.frag",
         "spv.depthOut.frag",
         "spv.discard-dce.frag",