Try to improve handling of failures during compilation

The change is mostly about trying to make sure the compiler "fails safe" when it encounters an internal assumption that isn't met.
Most internal errors will now throw exceptions (yes, exceptions are evil, but this will work for now), and these get caught in `spCompile` so that they don't propagate to the user (they just see a message that compilation aborted due to an internal error).

Subsequent changes are going to need to work on diagnosing as many of these situations as possible, so that users can at least know what construct in their code was unexpected or unhandled by the compiler.

1 files changed, 41 insertions, 36 deletions

diff --git a/source/slang/lower.cpp b/source/slang/lower.cpp
index c61003bc6..52b865ba3 100644
--- a/source/slang/lower.cpp
+++ b/source/slang/lower.cpp
@@ -186,7 +186,7 @@ class TupleVarDecl : public VarDeclBase
 public:
     virtual void accept(IDeclVisitor *, void *) override
     {
-        throw "unexpected";
+        SLANG_UNEXPECTED("tuples should not appear in lowered code");
     }
 
     TupleTypeModifier*          tupleType;
@@ -201,7 +201,7 @@ class TupleExpr : public ExpressionSyntaxNode
 public:
     virtual void accept(IExprVisitor *, void *) override
     {
-        throw "unexpected";
+        SLANG_UNEXPECTED("tuples should not appear in lowered code");
     }
 
     struct Element
@@ -225,7 +225,7 @@ class VaryingTupleVarDecl : public VarDeclBase
 public:
     virtual void accept(IDeclVisitor *, void *) override
     {
-        throw "unexpected";
+        SLANG_UNEXPECTED("tuples should not appear in lowered code");
     }
 };
 
@@ -236,7 +236,7 @@ class VaryingTupleExpr : public ExpressionSyntaxNode
 public:
     virtual void accept(IExprVisitor *, void *) override
     {
-        throw "unexpected";
+        SLANG_UNEXPECTED("tuples should not appear in lowered code");
     }
 
     struct Element
@@ -667,10 +667,10 @@ struct LoweringVisitor
         for (auto dd : decl->tupleDecls)
         {
             auto tupleVarMod = dd->FindModifier<TupleVarModifier>();
-            assert(tupleVarMod);
+            SLANG_RELEASE_ASSERT(tupleVarMod);
             auto tupleFieldMod = tupleVarMod->tupleField;
-            assert(tupleFieldMod);
-            assert(tupleFieldMod->decl);
+            SLANG_RELEASE_ASSERT(tupleFieldMod);
+            SLANG_RELEASE_ASSERT(tupleFieldMod->decl);
 
             TupleExpr::Element elem;
             elem.tupleFieldDeclRef = makeDeclRef(tupleFieldMod->decl);
@@ -799,7 +799,7 @@ struct LoweringVisitor
 
             if (leftTuple->primaryExpr)
             {
-                assert(rightTuple->primaryExpr);
+                SLANG_RELEASE_ASSERT(rightTuple->primaryExpr);
 
                 resultTuple->primaryExpr = createAssignExpr(
                     leftTuple->primaryExpr,
@@ -807,7 +807,7 @@ struct LoweringVisitor
             }
 
             auto elementCount = leftTuple->tupleElements.Count();
-            assert(elementCount == rightTuple->tupleElements.Count());
+            SLANG_RELEASE_ASSERT(elementCount == rightTuple->tupleElements.Count());
             for (UInt ee = 0; ee < elementCount; ++ee)
             {
                 auto leftElement = leftTuple->tupleElements[ee];
@@ -827,7 +827,7 @@ struct LoweringVisitor
         }
         else
         {
-            assert(!leftTuple && !rightTuple);
+            SLANG_RELEASE_ASSERT(!leftTuple && !rightTuple);
         }
 
         auto leftVaryingTuple = leftExpr.As<VaryingTupleExpr>();
@@ -838,10 +838,10 @@ struct LoweringVisitor
             resultTuple->Type.type = lowerType(leftExpr->Type.type);
             resultTuple->Position = leftExpr->Position;
 
-            assert(resultTuple->Type.type);
+            SLANG_RELEASE_ASSERT(resultTuple->Type.type);
 
             UInt elementCount = leftVaryingTuple->elements.Count();
-            assert(elementCount == rightVaryingTuple->elements.Count());
+            SLANG_RELEASE_ASSERT(elementCount == rightVaryingTuple->elements.Count());
 
             for (UInt ee = 0; ee < elementCount; ++ee)
             {
@@ -1027,7 +1027,7 @@ struct LoweringVisitor
             auto loweredExpr = new VaryingTupleExpr();
             loweredExpr->Type.type = getSubscripResultType(baseExpr->Type.type);
 
-            assert(loweredExpr->Type.type);
+            SLANG_RELEASE_ASSERT(loweredExpr->Type.type);
 
             for (auto elem : baseVaryingTuple->elements)
             {
@@ -1100,7 +1100,7 @@ struct LoweringVisitor
             RefPtr<AggTypeCtorExpr> resultExpr = new AggTypeCtorExpr();
             resultExpr->Type = varyingTupleExpr->Type;
             resultExpr->base.type = varyingTupleExpr->Type.type;
-            assert(resultExpr->Type.type);
+            SLANG_RELEASE_ASSERT(resultExpr->Type.type);
 
             for (auto elem : varyingTupleExpr->elements)
             {
@@ -1214,6 +1214,11 @@ struct LoweringVisitor
         return loweredExpr;
     }
 
+    DiagnosticSink* getSink()
+    {
+        return &shared->compileRequest->mSink;
+    }
+
     RefPtr<ExpressionSyntaxNode> visitMemberExpressionSyntaxNode(
         MemberExpressionSyntaxNode* expr)
     {
@@ -1244,8 +1249,8 @@ struct LoweringVisitor
                     return tupleFieldExpr;
 
                 auto tupleFieldTupleExpr = tupleFieldExpr.As<TupleExpr>();
-                assert(tupleFieldTupleExpr);
-                assert(!tupleFieldTupleExpr->primaryExpr);
+                SLANG_RELEASE_ASSERT(tupleFieldTupleExpr);
+                SLANG_RELEASE_ASSERT(!tupleFieldTupleExpr->primaryExpr);
 
 
                 RefPtr<MemberExpressionSyntaxNode> loweredPrimaryExpr = new MemberExpressionSyntaxNode();
@@ -1274,11 +1279,11 @@ struct LoweringVisitor
                 }
             }
 
-            assert(!"unexpected");
+            SLANG_DIAGNOSE_UNEXPECTED(getSink(), expr, "failed to find tuple field during lowering");
         }
 
         // Default handling:
-        assert(!dynamic_cast<TupleVarDecl*>(loweredDeclRef.getDecl()));
+        SLANG_RELEASE_ASSERT(!dynamic_cast<TupleVarDecl*>(loweredDeclRef.getDecl()));
 
         RefPtr<MemberExpressionSyntaxNode> loweredExpr = new MemberExpressionSyntaxNode();
         lowerExprCommon(loweredExpr, expr);
@@ -1344,7 +1349,7 @@ struct LoweringVisitor
                 return state->loweredStmt;
         }
 
-        assert(!"unexepcted");
+        SLANG_DIAGNOSE_UNEXPECTED(getSink(), originalStmt, "failed to find outer statement during lowering");
 
         return nullptr;
     }
@@ -1755,7 +1760,7 @@ struct LoweringVisitor
         if (auto litVal = dynamic_cast<ConstantIntVal*>(val))
             return val;
 
-        throw 99;
+        SLANG_UNEXPECTED("unhandled value kind");
     }
 
     RefPtr<Substitutions> translateSubstitutions(
@@ -1871,7 +1876,7 @@ struct LoweringVisitor
         // translated, which the user will maintain via pua/pop.
         //
 
-        assert(parentDecl);
+        SLANG_RELEASE_ASSERT(parentDecl);
         addMember(parentDecl, decl);
     }
 
@@ -2337,7 +2342,7 @@ struct LoweringVisitor
                 continue;
 
             // TODO: need to extract the initializer for this field
-            assert(!info.initExpr);
+            SLANG_RELEASE_ASSERT(!info.initExpr);
             RefPtr<ExpressionSyntaxNode> fieldInitExpr;
 
             String fieldName = info.name + "_" + dd.GetName();
@@ -2346,7 +2351,7 @@ struct LoweringVisitor
 
             Decl* originalFieldDecl;
             shared->mapLoweredDeclToOriginal.TryGetValue(dd, originalFieldDecl);
-            assert(originalFieldDecl);
+            SLANG_RELEASE_ASSERT(originalFieldDecl);
 
             RefPtr<VarLayout> fieldLayout;
             if(info.tupleTypeLayout)
@@ -2477,7 +2482,7 @@ struct LoweringVisitor
         RefPtr<StructTypeLayout>        tupleTypeLayout)
     {
         // Not handling initializers just yet...
-        assert(!initExpr);
+        SLANG_RELEASE_ASSERT(!initExpr);
 
         // We'll need a placeholder declaration to wrap the whole thing up:
         RefPtr<TupleVarDecl> tupleDecl = new TupleVarDecl();
@@ -2745,7 +2750,7 @@ struct LoweringVisitor
                     // declarations.
 
                     // We can't easily support `in out` declarations with this approach
-                    assert(!(inRes && outRes));
+                    SLANG_RELEASE_ASSERT(!(inRes && outRes));
 
                     RefPtr<ExpressionSyntaxNode> loweredExpr;
                     if (inRes)
@@ -2764,7 +2769,7 @@ struct LoweringVisitor
                             VaryingParameterDirection::Output);
                     }
 
-                    assert(loweredExpr);
+                    SLANG_RELEASE_ASSERT(loweredExpr);
                     auto loweredDecl = createVaryingTupleVarDecl(
                         decl,
                         loweredExpr);
@@ -2987,7 +2992,7 @@ struct LoweringVisitor
         RefPtr<ExpressionSyntaxNode> globalVarExpr;
 
         // Handle system-value inputs/outputs
-        assert(varLayout);
+        SLANG_RELEASE_ASSERT(varLayout);
         auto systemValueSemantic = varLayout->systemValueSemantic;
         if (systemValueSemantic.Length() != 0)
         {
@@ -3124,7 +3129,7 @@ struct LoweringVisitor
             }
             else
             {
-                assert(!"unhandled");
+                getSink()->diagnose(info.varChain->varDecl, Diagnostics::unknownSystemValueSemantic, systemValueSemantic);
             }
         }
 
@@ -3202,7 +3207,7 @@ struct LoweringVisitor
         RefPtr<ExpressionType>          varType,
         RefPtr<VarLayout>               varLayout)
     {
-        assert(varLayout);
+        SLANG_RELEASE_ASSERT(varLayout);
 
         if (auto basicType = varType->As<BasicExpressionType>())
         {
@@ -3252,7 +3257,7 @@ struct LoweringVisitor
                 RefPtr<VaryingTupleExpr> tupleExpr = new VaryingTupleExpr();
                 tupleExpr->Type.type = varType;
 
-                assert(tupleExpr->Type.type);
+                SLANG_RELEASE_ASSERT(tupleExpr->Type.type);
 
                 for (auto fieldDeclRef : getMembersOfType<VarDeclBase>(aggTypeDeclRef))
                 {
@@ -3271,14 +3276,14 @@ struct LoweringVisitor
                     // Need to find the layout for the given field...
                     Decl* originalFieldDecl = nullptr;
                     shared->mapLoweredDeclToOriginal.TryGetValue(fieldDeclRef.getDecl(), originalFieldDecl);
-                    assert(originalFieldDecl);
+                    SLANG_RELEASE_ASSERT(originalFieldDecl);
 
                     auto structTypeLayout = varLayout->typeLayout.As<StructTypeLayout>();
-                    assert(structTypeLayout);
+                    SLANG_RELEASE_EXPECT(structTypeLayout, "expected a structure type layout");
 
                     RefPtr<VarLayout> fieldLayout;
                     structTypeLayout->mapVarToLayout.TryGetValue(originalFieldDecl, fieldLayout);
-                    assert(fieldLayout);
+                    SLANG_RELEASE_ASSERT(fieldLayout);
 
                     auto loweredFieldExpr = lowerShaderParameterToGLSLGLobalsRec(
                         fieldInfo,
@@ -3414,7 +3419,7 @@ struct LoweringVisitor
         {
             RefPtr<VarLayout> paramLayout;
             entryPointLayout->mapVarToLayout.TryGetValue(paramDecl.Ptr(), paramLayout);
-            assert(paramLayout);
+            SLANG_RELEASE_ASSERT(paramLayout);
 
             RefPtr<Variable> localVarDecl = new Variable();
             localVarDecl->Position = paramDecl->Position;
@@ -3657,13 +3662,13 @@ static RefPtr<StructTypeLayout> getGlobalStructLayout(
         auto elementTypeStructLayout = elementTypeLayout.As<StructTypeLayout>();
 
         // We expect all constant buffers to contain `struct` types for now
-        assert(elementTypeStructLayout);
+        SLANG_RELEASE_ASSERT(elementTypeStructLayout);
 
         globalStructLayout = elementTypeStructLayout.Ptr();
     }
     else
     {
-        assert(!"unexpected");
+        SLANG_UNEXPECTED("unhandled type for global-scope parameter layout");
     }
     return globalStructLayout;
 }