From 1406aa2bc9e398e5e5565ba9c6adbb780c29fee1 Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Wed, 13 Dec 2023 12:24:27 -0800
Subject: Add spirv intrinsics for `ConstBufferPointer`. (#3407)

Fixes #3305.
Fixes #3404.

Co-authored-by: Yong He <yhe@nvidia.com>
---
 source/slang/hlsl.meta.slang      | 34 ++++++++++++++++++++++++++++++++--
 source/slang/slang-emit-spirv.cpp | 15 +++++++++++++--
 2 files changed, 45 insertions(+), 4 deletions(-)

(limited to 'source')

diff --git a/source/slang/hlsl.meta.slang b/source/slang/hlsl.meta.slang
index 477e0cfaf..39ed13488 100644
--- a/source/slang/hlsl.meta.slang
+++ b/source/slang/hlsl.meta.slang
@@ -12546,7 +12546,37 @@ struct ConstBufferPointer
 {
     __glsl_version(450)
     __glsl_extension(GL_EXT_buffer_reference)
-    __target_intrinsic(glsl, "$0._data")
     [__NoSideEffect]
-    T get();
+    T get()
+    {
+        __target_switch
+        {
+        case glsl:
+            __intrinsic_asm "$0._data";
+        case spirv:
+            return spirv_asm {
+                result:$$T = OpLoad $this Aligned $Alignment;
+            };
+        }
+    }
+
+    __glsl_version(450)
+    __glsl_extension(GL_EXT_shader_explicit_arithmetic_types_int64)
+    __glsl_extension(GL_EXT_buffer_reference)
+    [__NoSideEffect]
+    [ForceInline]
+    bool isValid()
+    {
+        __target_switch
+        {
+        case glsl:
+            __intrinsic_asm "(uint64_t($0) != 0)";
+        case spirv:
+            uint64_t zero = 0ULL;
+            return spirv_asm {
+                %ptrval:$$uint64_t = OpConvertPtrToU $this;
+                result:$$bool = OpINotEqual %ptrval $zero;
+            };
+        }
+    }
 }
diff --git a/source/slang/slang-emit-spirv.cpp b/source/slang/slang-emit-spirv.cpp
index d071328c4..5939754e0 100644
--- a/source/slang/slang-emit-spirv.cpp
+++ b/source/slang/slang-emit-spirv.cpp
@@ -429,6 +429,8 @@ struct SPIRVEmitContext
         /// The next destination `<id>` to allocate.
     SpvWord m_nextID = 1;
 
+    SpvAddressingModel m_addressingMode = SpvAddressingModelLogical;
+
     // We will store the logical sections of the SPIR-V module
     // in a single array so that we can easily look up a
     // section by its `SpvLogicalSectionID`.
@@ -1200,7 +1202,7 @@ struct SPIRVEmitContext
         emitOpMemoryModel(
             getSection(SpvLogicalSectionID::MemoryModel),
             nullptr,
-            SpvAddressingModelLogical,
+            m_addressingMode,
             SpvMemoryModelGLSL450
         );
     }
@@ -1394,6 +1396,14 @@ struct SPIRVEmitContext
             requireSPIRVCapability(SpvCapabilityShaderInvocationReorderNV);
             return emitOpTypeHitObject(inst);
 
+        case kIROp_HLSLConstBufferPointerType:
+            ensureExtensionDeclaration(UnownedStringSlice("SPV_KHR_variable_pointers"));
+            requireSPIRVCapability(SpvCapabilityVariablePointers);
+            ensureExtensionDeclaration(UnownedStringSlice("SPV_KHR_physical_storage_buffer"));
+            requireSPIRVCapability(SpvCapabilityPhysicalStorageBufferAddresses);
+            m_addressingMode = SpvAddressingModelPhysicalStorageBuffer64;
+            return emitOpTypePointer(inst, SpvStorageClassPhysicalStorageBuffer, inst->getOperand(0));
+
         case kIROp_FuncType:
             // > OpTypeFunction
             //
@@ -4908,7 +4918,6 @@ SlangResult emitSPIRVFromIR(
     }
 #endif
 
-    context.emitFrontMatter();
     for (auto inst : irModule->getGlobalInsts())
     {
         if (as<IRDebugSource>(inst))
@@ -4925,6 +4934,8 @@ SlangResult emitSPIRVFromIR(
     {
         context.ensureInst(irEntryPoint);
     }
+    context.emitFrontMatter();
+
     context.emitPhysicalLayout();
 
     spirvOut.addRange(
-- 
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