Fix Phi simplification bug. (#2710)

* Fix Phi simplification bug.

* Fix up.

* Fix.

* Fix.

* Fix.

* Fix.

* Fix.

* Fix test.

* Fix test.

---------

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

1 files changed, 25 insertions, 3 deletions

diff --git a/source/slang/slang-ir-validate.cpp b/source/slang/slang-ir-validate.cpp
index 55e0f0168..3c720e929 100644
--- a/source/slang/slang-ir-validate.cpp
+++ b/source/slang/slang-ir-validate.cpp
@@ -3,6 +3,7 @@
 
 #include "slang-ir.h"
 #include "slang-ir-insts.h"
+#include "slang-ir-dominators.h"
 
 namespace Slang
 {
@@ -11,6 +12,8 @@ namespace Slang
         // The IR module we are validating.
         IRModule*           module;
 
+        RefPtr<IRDominatorTree> domTree;
+
         // A diagnostic sink to send errors to if anything is invalid.
         DiagnosticSink*     sink;
 
@@ -165,9 +168,14 @@ namespace Slang
                     // the same function (or another value with code). We need
                     // to validate that `operandParentBlock` dominates `instParentBlock`.
                     //
-                    // TODO: implement this validation once we compute dominator trees.
-                    //
-                    // validate(context, operandParentBlock->dominates(instParentBlock),    inst, "def must dominate use");
+                    if (context && context->domTree)
+                    {
+                        validate(
+                            context,
+                            context->domTree->dominates(operandParentBlock, instParentBlock),
+                            inst,
+                            "def must dominate use");
+                    }
                     return;
                 }
             }
@@ -327,10 +335,24 @@ namespace Slang
 
         if (auto code = as<IRGlobalValueWithCode>(inst))
         {
+            context->domTree = computeDominatorTree(code);
             validateCodeBody(context, code);
+            context->domTree = nullptr;
         }
     }
 
+    void validateIRInst(IRInst* inst)
+    {
+        IRValidateContext contextStorage;
+        IRValidateContext* context = &contextStorage;
+        DiagnosticSink sink;
+        context->module = inst->getModule();
+        context->sink = &sink;
+        if (auto func = as<IRFunc>(inst))
+            context->domTree = computeDominatorTree(func);
+        validateIRInst(context, inst);
+    }
+
     void validateIRModule(IRModule* module, DiagnosticSink* sink)
     {
         IRValidateContext contextStorage;