[DropUnnecessaryAssumes] Don't drop public_type_test intrinsic (#166034)

Don't drop `assume` intrinsic when it's using `public_type_test `
intrinsic, as it could be used by devirtualization.

Author: hassnaaHamdi

llvm/lib/Transforms/Scalar/DropUnnecessaryAssumes.cpp

@@ -122,7 +122,8 @@ DropUnnecessaryAssumesPass::run(Function &F, FunctionAnalysisManager &FAM) {
 
     Value *Cond = Assume->getArgOperand(0);
     // Don't drop type tests, which have special semantics.
-    if (match(Cond, m_Intrinsic<Intrinsic::type_test>()))
+    if (match(Cond, m_Intrinsic<Intrinsic::type_test>()) ||
+        match(Cond, m_Intrinsic<Intrinsic::public_type_test>()))
       continue;
 
     SmallVector<Value *> Affected;

llvm/test/Transforms/DropUnnecessaryAssumes/basic.ll

@@ -184,6 +184,18 @@ define void @type_test(ptr %x) {
   ret void
 }
 
+define void @public_type_test(ptr %x) {
+; CHECK-LABEL: define void @public_type_test(
+; CHECK-SAME: ptr [[X:%.*]]) {
+; CHECK-NEXT:    [[TEST:%.*]] = call i1 @llvm.public.type.test(ptr [[X]], metadata !"typeid")
+; CHECK-NEXT:    call void @llvm.assume(i1 [[TEST]])
+; CHECK-NEXT:    ret void
+;
+  %test = call i1 @llvm.public.type.test(ptr %x, metadata !"typeid")
+  call void @llvm.assume(i1 %test)
+  ret void
+}
+
 define void @multiple_dead_conds(i32 %x) {
 ; CHECK-LABEL: define void @multiple_dead_conds(
 ; CHECK-SAME: i32 [[X:%.*]]) {