[SM6.9] Fix LV cast crash (microsoft#8008)

Fixes microsoft#7915 

There is a detailed writeup in the issue but in summary, native vectors
in SM6.9 shouldn't be optimized in the way this path enables and weren't
cleanly being rejected. This change now rejects them

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: V-FEXrt

lib/Transforms/Scalar/Float2Int.cpp

@@ -129,19 +129,25 @@ static Instruction::BinaryOps mapBinOpcode(unsigned Opcode) {
 
 // Find the roots - instructions that convert from the FP domain to
 // integer domain.
+// findRoots updated from upstream to skip vectors
 void Float2Int::findRoots(Function &F, SmallPtrSet<Instruction*,8> &Roots) {
-  for (auto &I : inst_range(F)) {
-    switch (I.getOpcode()) {
-    default: break;
-    case Instruction::FPToUI:
-    case Instruction::FPToSI:
-      Roots.insert(&I);
-      break;
-    case Instruction::FCmp:
-      if (mapFCmpPred(cast<CmpInst>(&I)->getPredicate()) != 
-          CmpInst::BAD_ICMP_PREDICATE)
+  for (BasicBlock &BB : F) {
+    for (Instruction &I : BB) {
+      if (isa<VectorType>(I.getType()))
+        continue;
+      switch (I.getOpcode()) {
+      default:
+        break;
+      case Instruction::FPToUI:
+      case Instruction::FPToSI:
         Roots.insert(&I);
-      break;
+        break;
+      case Instruction::FCmp:
+        if (mapFCmpPred(cast<CmpInst>(&I)->getPredicate()) !=
+            CmpInst::BAD_ICMP_PREDICATE)
+          Roots.insert(&I);
+        break;
+      }
     }
   }
 }
@@ -400,7 +406,7 @@ bool Float2Int::validateAndTransform() {
         R.isFullSet() || R.isSignWrappedSet())
       continue;
     assert(ConvertedToTy && "Must have set the convertedtoty by this point!");
-    
+
     // The number of bits required is the maximum of the upper and
     // lower limits, plus one so it can be signed.
     unsigned MinBW = std::max(R.getLower().getMinSignedBits(),

tools/clang/test/HLSLFileCheck/hlsl/types/cast/cast8.hlsl

@@ -0,0 +1,26 @@
+// RUN: %dxc -T cs_6_9 -DFTYPE=float2 %s | FileCheck %s
+// RUN: %dxc -T cs_6_9 -DFTYPE=half2 -enable-16bit-types %s | FileCheck %s
+
+
+// https://github.com/microsoft/DirectXShaderCompiler/issues/7915
+// Test long vector casting between uint2 and float2
+// which would crash as reported by a user.
+
+// CHECK: call %dx.types.Handle @dx.op.createHandleFromBinding
+// CHECK: fptoui
+// CHECK: uitofp
+// CHECK: fptoui
+// CHECK: uitofp
+// CHECK: call void @dx.op.rawBufferVectorStore
+
+RWStructuredBuffer<FTYPE> input;
+RWStructuredBuffer<FTYPE> output;
+
+FTYPE f1(uint2 p) { return p; }
+uint2 f2(FTYPE p) { return f1(p); }
+
+[numthreads(1,1,1)]
+void main()
+{
+  output[0] = f2(input[0]);
+}