From 8f962894fd38edb47d782d303ac9ff87b3a3bb6a Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Fri, 4 Sep 2020 10:18:44 -0700
Subject: Allow mixing unspecialized and specialized existential parameters.
 (#1533)

* Allow mixing unspecialized and specialized existential parameters.

* Fixes.
---
 source/slang/slang-ir-lower-existential.cpp | 31 +++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

(limited to 'source/slang/slang-ir-lower-existential.cpp')

diff --git a/source/slang/slang-ir-lower-existential.cpp b/source/slang/slang-ir-lower-existential.cpp
index a6db2b781..0dce96de2 100644
--- a/source/slang/slang-ir-lower-existential.cpp
+++ b/source/slang/slang-ir-lower-existential.cpp
@@ -7,6 +7,9 @@
 
 namespace Slang
 {
+    bool isCPUTarget(TargetRequest* targetReq);
+    bool isCUDATarget(TargetRequest* targetReq);
+
     struct ExistentialLoweringContext
     {
         SharedGenericsLoweringContext* sharedContext;
@@ -79,12 +82,40 @@ namespace Slang
             processExtractExistentialElement(inst, 0);
         }
 
+        void processGetValueFromExistentialBox(IRGetValueFromExistentialBox* inst)
+        {
+            // Currently we do not translate on HLSL/GLSL targets,
+            // since we don't attempt to actually layout the value inside an fixed sized
+            // existential box for these targets.
+            if (isCPUTarget(sharedContext->targetReq) || isCUDATarget(sharedContext->targetReq))
+            {
+                IRBuilder builderStorage;
+                auto builder = &builderStorage;
+                builder->sharedBuilder = &sharedContext->sharedBuilderStorage;
+                builder->setInsertBefore(inst);
+
+                auto element = extractTupleElement(builder, inst->getOperand(0), 2);
+                // TODO: it is not technically sound to use `getAddress` on a temporary value.
+                // We probably need to develop a mechanism to allow a temporary value to be used
+                // in the place of a pointer.
+                auto elementAddr =
+                    builder->emitGetAddress(builder->getPtrType(element->getDataType()), element);
+                auto reinterpretAddr = builder->emitBitCast(inst->getDataType(), elementAddr);
+                inst->replaceUsesWith(reinterpretAddr);
+                inst->removeAndDeallocate();
+            }
+        }
+
         void processInst(IRInst* inst)
         {
             if (auto makeExistential = as<IRMakeExistentialWithRTTI>(inst))
             {
                 processMakeExistential(makeExistential);
             }
+            else if (auto getExistentialValue = as<IRGetValueFromExistentialBox>(inst))
+            {
+                processGetValueFromExistentialBox(getExistentialValue);
+            }
             else if (auto extractExistentialVal = as<IRExtractExistentialValue>(inst))
             {
                 processExtractExistentialValue(extractExistentialVal);
-- 
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