From ab5b0a7f9fbc47f7c51a7ec4a20ac0be55333e93 Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Fri, 28 Aug 2020 09:04:55 -0700
Subject: Enable lower-generics pass universally. (#1518)

* Enable lower-generics pass universally.

* Exclude builtin interfaces and functions from lower-generics pass.

* Update stdlib.

* Fixup.

* Fixes handling of nested intrinsic generic functions.

* Fixes.

* Fixes.
---
 source/slang/slang-ir-lower-generic-function.cpp | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

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

diff --git a/source/slang/slang-ir-lower-generic-function.cpp b/source/slang/slang-ir-lower-generic-function.cpp
index f9a7e0a24..c02e9e3d6 100644
--- a/source/slang/slang-ir-lower-generic-function.cpp
+++ b/source/slang/slang-ir-lower-generic-function.cpp
@@ -21,9 +21,21 @@ namespace Slang
             IRInst* result = nullptr;
             if (sharedContext->loweredGenericFunctions.TryGetValue(genericValue, result))
                 return result;
+            // Do not lower intrinsic functions.
+            if (genericValue->findDecoration<IRTargetIntrinsicDecoration>())
+                return genericValue;
             auto genericParent = as<IRGeneric>(genericValue);
             SLANG_ASSERT(genericParent);
             auto func = as<IRFunc>(findGenericReturnVal(genericParent));
+            if (!func)
+            {
+                // Nested generic functions are supposed to be flattened before entering
+                // this pass. The reason we are still seeing them must be that they are
+                // intrinsic functions. In this case we ignore the function.
+                SLANG_ASSERT(findInnerMostGenericReturnVal(genericParent)
+                                 ->findDecoration<IRTargetIntrinsicDecoration>() != nullptr);
+                return genericValue;
+            }
             SLANG_ASSERT(func);
             if (!func->isDefinition())
             {
@@ -133,7 +145,9 @@ namespace Slang
                 return loweredType;
             if (sharedContext->mapLoweredInterfaceToOriginal.ContainsKey(interfaceType))
                 return interfaceType;
-
+            // Do not lower intrinsic interfaces.
+            if (isBuiltin(interfaceType))
+                return interfaceType;
             List<IRInterfaceRequirementEntry*> newEntries;
 
             IRBuilder builder;
@@ -189,6 +203,8 @@ namespace Slang
             auto interfaceType = maybeLowerInterfaceType(cast<IRInterfaceType>(witnessTable->getConformanceType()));
             if (interfaceType != witnessTable->getConformanceType())
                 witnessTable->setConformanceType(interfaceType);
+            if (isBuiltin(interfaceType))
+                return;
             for (auto child : witnessTable->getChildren())
             {
                 auto entry = as<IRWitnessTableEntry>(child);
-- 
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