Warnings target switch intrinsic asm (#4727)

* Proper warning generation for target switches and intrinsic asm

* Relaxing terminators

* Fix compiler warnings

* Rectified target switch reachability check

* Simplify target switch reachability check

* Refactoring variable names

* Using getBlocks

* Moving ad hoc special case to diagnostics source

* Using the LINE directive for testing

* Simplifying reliance on target switches

* Skipping IR generation for empty target switches

---------

Co-authored-by: Yong He <yonghe@outlook.com>

1 files changed, 29 insertions, 7 deletions

diff --git a/source/slang/slang-ir-reachability.cpp b/source/slang/slang-ir-reachability.cpp
index 1a4aa271b..5a9d732ca 100644
--- a/source/slang/slang-ir-reachability.cpp
+++ b/source/slang/slang-ir-reachability.cpp
@@ -1,19 +1,20 @@
 #include "slang-ir-reachability.h"
+#include "slang-ir-insts.h"
+#include "slang-ir-util.h"
 
 namespace Slang
 {
-// Computes whether block1 can reach block2.
-// A block is considered not reachable from itself unless there is a backedge in the CFG.
-
+    // Computes whether block1 can reach block2.
+    // A block is considered not reachable from itself unless there is a backedge in the CFG.
     ReachabilityContext::ReachabilityContext(IRGlobalValueWithCode* code)
     {
         int id = 0;
         for (auto block : code->getBlocks())
         {
-            mapBlockToId[block] = id;
-            id++;
+            mapBlockToId[block] = id++;
             allBlocks.add(block);
         }
+
         sourceBlocks.setCount(allBlocks.getCount());
         for (auto &srcBlock : sourceBlocks)
             srcBlock.resizeAndClear(allBlocks.getCount());
@@ -23,6 +24,7 @@ namespace Slang
 
         List<IRBlock*> workList;
         List<IRBlock*> pendingWorkList;
+
         workList.add(allBlocks[0]);
         while (workList.getCount())
         {
@@ -52,17 +54,37 @@ namespace Slang
             }
             workList.swapWith(pendingWorkList);
         }
+    }
+    
+    bool ReachabilityContext::isInstReachable(IRInst* from, IRInst* to)
+    {
+        // If inst1 and inst2 are in the same block,
+        // we test if inst2 appears after inst1.
+        if (getBlock(from) == getBlock(to))
+        {
+            for (auto inst = from->getNextInst(); inst; inst = inst->getNextInst())
+            {
+                if (inst == to)
+                    return true;
+            }
+        }
 
+        return isBlockReachable(getBlock(from), getBlock(to));
     }
 
     bool ReachabilityContext::isBlockReachable(IRBlock* from, IRBlock* to)
     {
-        if (!from) return false;
-        if (!to) return false;
+        if (!from)
+            return false;
+
+        if (!to)
+            return false;
+
         int* fromId = mapBlockToId.tryGetValue(from);
         int* toId = mapBlockToId.tryGetValue(to);
         if (!fromId || !toId)
             return true;
+
         return sourceBlocks[*toId].contains(*fromId);
     }
 }