Fix crash in dominator tree construction used by DiagnoseRaytracingPa…

…yloadAccess (microsoft#5605) Fix crash if a RayGen shader contains a `while(true)` loop, caused by dominator tree construction not ignoring `nullptr` successor AST nodes which occur in this case. Also add regression test case. Fixes microsoft#5035. Co-authored-by: Jannik Silvanus <[email protected]>
cassiebeckley · Feb 21, 2024 · 16d43a5 · 16d43a5
1 parent 22bb078
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diff --git a/include/llvm/Support/GenericDomTreeConstruction.h b/include/llvm/Support/GenericDomTreeConstruction.h
@@ -92,6 +92,10 @@ unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT,
     // Visit the successor next, if it isn't already visited.
     typename GraphT::NodeType* Succ = *NextSucc;
 
+    // For clang, CFG successors can be optimized-out nullptrs. Skip those.
+    if (!Succ)
+      continue;
+
     typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &SuccVInfo =
                                                                   DT.Info[Succ];
     if (SuccVInfo.Semi == 0) {

diff --git a/...est/HLSLFileCheck/hlsl/diagnostics/warnings/diagnose_raytracing_payload_access_crash.hlsl b/...est/HLSLFileCheck/hlsl/diagnostics/warnings/diagnose_raytracing_payload_access_crash.hlsl
@@ -0,0 +1,11 @@
+// RUN: %dxc -E RayGen -T lib_6_7 %s | FileCheck %s
+
+// Regression test for crashing in DiagnoseRaytracingPayloadAccess
+// due to a trivial while(true) loop.
+
+// CHECK: define void @"\01?RayGen@@YAXXZ"()
+[shader("raygeneration")] void RayGen() {
+    while (true) {
+       break;
+    }
+}