Fix div-by-zero error during sccp. (#2911)

* Diagnose on div-by-zero during sccp.

* fix

---------

Co-authored-by: Yong He <yhe@nvidia.com>

8 files changed, 89 insertions, 25 deletions

diff --git a/source/slang/slang-emit.cpp b/source/slang/slang-emit.cpp
index a96cb6908..f1ec402dd 100644
--- a/source/slang/slang-emit.cpp
+++ b/source/slang/slang-emit.cpp
@@ -324,7 +324,7 @@ Result linkAndOptimizeIR(
     }
 
     lowerOptionalType(irModule, sink);
-    simplifyIR(irModule);
+    simplifyIR(irModule, sink);
 
     switch (target)
     {
@@ -450,7 +450,7 @@ Result linkAndOptimizeIR(
 
     validateIRModuleIfEnabled(codeGenContext, irModule);
 
-    simplifyIR(irModule);
+    simplifyIR(irModule, sink);
 
     if (!ArtifactDescUtil::isCpuLikeTarget(artifactDesc))
     {
@@ -483,7 +483,7 @@ Result linkAndOptimizeIR(
     // up downstream passes like type legalization, so we
     // will run a DCE pass to clean up after the specialization.
     //
-    simplifyIR(irModule);
+    simplifyIR(irModule, sink);
 
 #if 0
     dumpIRIfEnabled(codeGenContext, irModule, "AFTER DCE");
@@ -565,7 +565,7 @@ Result linkAndOptimizeIR(
     // to see if we can clean up any temporaries created by legalization.
     // (e.g., things that used to be aggregated might now be split up,
     // so that we can work with the individual fields).
-    simplifyIR(irModule);
+    simplifyIR(irModule, sink);
 
 #if 0
     dumpIRIfEnabled(codeGenContext, irModule, "AFTER SSA");
@@ -591,7 +591,7 @@ Result linkAndOptimizeIR(
     {
         specializeArrayParameters(codeGenContext, irModule);
     }
-    simplifyIR(irModule);
+    simplifyIR(irModule, sink);
 
     // Rewrite functions that return arrays to return them via `out` parameter,
     // since our target languages doesn't allow returning arrays.
@@ -835,7 +835,7 @@ Result linkAndOptimizeIR(
     //
     // We run IR simplification passes again to clean things up.
     //
-    simplifyIR(irModule);
+    simplifyIR(irModule, sink);
 
     if (isKhronosTarget(targetRequest))
     {
@@ -865,7 +865,7 @@ Result linkAndOptimizeIR(
     // Lower all bit_cast operations on complex types into leaf-level
     // bit_cast on basic types.
     lowerBitCast(targetRequest, irModule);
-    simplifyIR(irModule);
+    simplifyIR(irModule, sink);
 
     eliminateMultiLevelBreak(irModule);
 
diff --git a/source/slang/slang-ir-autodiff-fwd.cpp b/source/slang/slang-ir-autodiff-fwd.cpp
index 38d0c0706..f1099547c 100644
--- a/source/slang/slang-ir-autodiff-fwd.cpp
+++ b/source/slang/slang-ir-autodiff-fwd.cpp
@@ -591,7 +591,8 @@ InstPair ForwardDiffTranscriber::transcribeCall(IRBuilder* builder, IRCall* orig
     }
     else
     {
-        diffCallee = findOrTranscribeDiffInst(builder, origCallee);
+        if (_isDifferentiableFunc(origCallee))
+            diffCallee = findOrTranscribeDiffInst(builder, origCallee);
         primalCallee = substPrimalCallee;
     }
 
diff --git a/source/slang/slang-ir-sccp.cpp b/source/slang/slang-ir-sccp.cpp
index 9ad51e0e6..d5e4c6e99 100644
--- a/source/slang/slang-ir-sccp.cpp
+++ b/source/slang/slang-ir-sccp.cpp
@@ -15,6 +15,7 @@ namespace Slang {
 struct SharedSCCPContext
 {
     IRModule*       module;
+    DiagnosticSink* sink;
 };
 //
 // Next we have a context struct that will be applied for each function (or other
@@ -580,7 +581,7 @@ struct SCCPContext
             type,
             v0,
             v1,
-            [](IRIntegerValue c0, IRIntegerValue c1) { return c0 / c1; },
+            [](IRIntegerValue c0, IRIntegerValue c1) {  return c0 / c1; },
             [](IRFloatingPointValue c0, IRFloatingPointValue c1) { return c0 / c1; });
     }
     LatticeVal evalEql(IRType* type, LatticeVal v0, LatticeVal v1)
@@ -870,10 +871,27 @@ struct SCCPContext
                 getLatticeVal(inst->getOperand(0)),
                 getLatticeVal(inst->getOperand(1)));
         case kIROp_Div:
+        {
+            // Detect divide by zero error.
+            auto divisor = getLatticeVal(inst->getOperand(1));
+            if (divisor.flavor == LatticeVal::Flavor::Constant)
+            {
+                if (isIntegralType(divisor.value->getDataType()))
+                {
+                    auto c = as<IRConstant>(divisor.value);
+                    if (c->value.intVal == 0)
+                    {
+                        if (shared->sink)
+                            shared->sink->diagnose(inst->sourceLoc, Diagnostics::divideByZero);
+                        return LatticeVal::getAny();
+                    }
+                }
+            }
             return evalDiv(
                 inst->getDataType(),
                 getLatticeVal(inst->getOperand(0)),
-                getLatticeVal(inst->getOperand(1)));
+                divisor);
+        }
         case kIROp_Eql:
             return evalEql(
                 inst->getDataType(),
@@ -1658,10 +1676,15 @@ static bool applySparseConditionalConstantPropagationRec(
 }
 
 bool applySparseConditionalConstantPropagation(
-    IRModule*       module)
+    IRModule*       module,
+    DiagnosticSink* sink)
 {
+    if (sink && sink->getErrorCount())
+        return false;
+
     SharedSCCPContext shared;
     shared.module = module;
+    shared.sink = sink;
 
     // First we fold constants at global scope.
     SCCPContext globalContext;
@@ -1676,10 +1699,15 @@ bool applySparseConditionalConstantPropagation(
 }
 
 bool applySparseConditionalConstantPropagationForGlobalScope(
-    IRModule* module)
+    IRModule* module,
+    DiagnosticSink* sink)
 {
+    if (sink && sink->getErrorCount())
+        return false;
+
     SharedSCCPContext shared;
     shared.module = module;
+    shared.sink = sink;
     SCCPContext globalContext;
     globalContext.shared = &shared;
     globalContext.code = nullptr;
@@ -1687,10 +1715,14 @@ bool applySparseConditionalConstantPropagationForGlobalScope(
     return changed;
 }
 
-bool applySparseConditionalConstantPropagation(IRInst* func)
+bool applySparseConditionalConstantPropagation(IRInst* func, DiagnosticSink* sink)
 {
+    if (sink && sink->getErrorCount())
+        return false;
+
     SharedSCCPContext shared;
     shared.module = func->getModule();
+    shared.sink = sink;
 
     SCCPContext globalContext;
     globalContext.shared = &shared;
diff --git a/source/slang/slang-ir-sccp.h b/source/slang/slang-ir-sccp.h
index 7b83ce10f..776caec9a 100644
--- a/source/slang/slang-ir-sccp.h
+++ b/source/slang/slang-ir-sccp.h
@@ -5,6 +5,7 @@ namespace Slang
 {
     struct IRModule;
     struct IRInst;
+    class DiagnosticSink;
 
         /// Apply Sparse Conditional Constant Propagation (SCCP) to a module.
         ///
@@ -15,11 +16,13 @@ namespace Slang
         /// becoming dead code)
         /// Returns true if IR is changed.
     bool applySparseConditionalConstantPropagation(
-        IRModule*       module);
+        IRModule*       module,
+        DiagnosticSink* sink);
     bool applySparseConditionalConstantPropagationForGlobalScope(
-        IRModule* module);
+        IRModule* module,
+        DiagnosticSink* sink);
 
-    bool applySparseConditionalConstantPropagation(IRInst* func);
+    bool applySparseConditionalConstantPropagation(IRInst* func, DiagnosticSink* sink);
 
     IRInst* tryConstantFoldInst(IRModule* module, IRInst* inst);
 }
diff --git a/source/slang/slang-ir-ssa-simplification.cpp b/source/slang/slang-ir-ssa-simplification.cpp
index e6c6e353f..66b4ceccb 100644
--- a/source/slang/slang-ir-ssa-simplification.cpp
+++ b/source/slang/slang-ir-ssa-simplification.cpp
@@ -16,7 +16,7 @@ namespace Slang
 {
     // Run a combination of SSA, SCCP, SimplifyCFG, and DeadCodeElimination pass
     // until no more changes are possible.
-    void simplifyIR(IRModule* module)
+    void simplifyIR(IRModule* module, DiagnosticSink* sink)
     {
         bool changed = true;
         const int kMaxIterations = 8;
@@ -25,12 +25,16 @@ namespace Slang
 
         while (changed && iterationCounter < kMaxIterations)
         {
+            if (sink && sink->getErrorCount())
+                break;
+
             changed = false;
+
             changed |= hoistConstants(module);
             changed |= deduplicateGenericChildren(module);
             changed |= propagateFuncProperties(module);
             changed |= removeUnusedGenericParam(module);
-            changed |= applySparseConditionalConstantPropagationForGlobalScope(module);
+            changed |= applySparseConditionalConstantPropagationForGlobalScope(module, sink);
             changed |= peepholeOptimize(module);
 
             for (auto inst : module->getGlobalInsts())
@@ -43,7 +47,7 @@ namespace Slang
                 while (funcChanged && funcIterationCount < kMaxFuncIterations)
                 {
                     funcChanged = false;
-                    funcChanged |= applySparseConditionalConstantPropagation(func);
+                    funcChanged |= applySparseConditionalConstantPropagation(func, sink);
                     funcChanged |= peepholeOptimize(func);
                     funcChanged |= removeRedundancyInFunc(func);
                     funcChanged |= simplifyCFG(func);
@@ -85,15 +89,18 @@ namespace Slang
     }
 
 
-    void simplifyFunc(IRGlobalValueWithCode* func)
+    void simplifyFunc(IRGlobalValueWithCode* func, DiagnosticSink* sink)
     {
         bool changed = true;
         const int kMaxIterations = 8;
         int iterationCounter = 0;
         while (changed && iterationCounter < kMaxIterations)
         {
+            if (sink && sink->getErrorCount())
+                break;
+
             changed = false;
-            changed |= applySparseConditionalConstantPropagation(func);
+            changed |= applySparseConditionalConstantPropagation(func, sink);
             changed |= peepholeOptimize(func);
             changed |= removeRedundancyInFunc(func);
             changed |= simplifyCFG(func);
@@ -106,6 +113,7 @@ namespace Slang
             changed |= constructSSA(func);
 
             iterationCounter++;
+
         }
     }
 }
diff --git a/source/slang/slang-ir-ssa-simplification.h b/source/slang/slang-ir-ssa-simplification.h
index 39504e102..fd7aa0ad8 100644
--- a/source/slang/slang-ir-ssa-simplification.h
+++ b/source/slang/slang-ir-ssa-simplification.h
@@ -5,13 +5,14 @@ namespace Slang
 {
     struct IRModule;
     struct IRGlobalValueWithCode;
+    class DiagnosticSink;
 
     // Run a combination of SSA, SCCP, SimplifyCFG, and DeadCodeElimination pass
     // until no more changes are possible.
-    void simplifyIR(IRModule* module);
+    void simplifyIR(IRModule* module, DiagnosticSink* sink = nullptr);
 
     // Run simplifications on IR that is out of SSA form.
     void simplifyNonSSAIR(IRModule* module);
 
-    void simplifyFunc(IRGlobalValueWithCode* func);
+    void simplifyFunc(IRGlobalValueWithCode* func, DiagnosticSink* sink = nullptr);
 }
diff --git a/source/slang/slang-lower-to-ir.cpp b/source/slang/slang-lower-to-ir.cpp
index 486c152d5..b36f0dc94 100644
--- a/source/slang/slang-lower-to-ir.cpp
+++ b/source/slang/slang-lower-to-ir.cpp
@@ -9657,7 +9657,7 @@ RefPtr<IRModule> generateIRForTranslationUnit(
     //
     constructSSA(module);
     simplifyCFG(module);
-    applySparseConditionalConstantPropagation(module);
+    applySparseConditionalConstantPropagation(module, compileRequest->getSink());
 
     // Next, inline calls to any functions that have been
     // marked for mandatory "early" inlining.
@@ -9677,7 +9677,7 @@ RefPtr<IRModule> generateIRForTranslationUnit(
     //
     constructSSA(module);
     simplifyCFG(module);
-    applySparseConditionalConstantPropagation(module);
+    applySparseConditionalConstantPropagation(module, compileRequest->getSink());
 
     // Propagate `constexpr`-ness through the dataflow graph (and the
     // call graph) based on constraints imposed by different instructions.
diff --git a/tests/diagnostics/sccp-div-by-zero.slang b/tests/diagnostics/sccp-div-by-zero.slang
new file mode 100644
index 000000000..b7c85fe10
--- /dev/null
+++ b/tests/diagnostics/sccp-div-by-zero.slang
@@ -0,0 +1,19 @@
+//TEST:SIMPLE(filecheck=CHECK): -entry computeMain -profile cs_5_0 -target hlsl
+RWStructuredBuffer<uint> outputBuffer;
+
+// CHECK: divide by zero
+uint check<let b : bool>()
+{
+    return 1 / int(b);
+}
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+	uint tid = dispatchThreadID.x;
+    
+    uint a = check<false>();
+    uint b = check<true>();
+    
+	outputBuffer[tid] = a + b; 
+}
\ No newline at end of file