[DeviceSanitizer] Always cleanup private shadow memory before using it (#15065)

For global, local shadow memory, we will cleanup it before using it. So,
we also need to do this for private shadow memory to avoid shadow value
pollutions.

Author: zhaomaosu

llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp

@@ -4079,6 +4079,15 @@ void FunctionStackPoisoner::processStaticAllocas() {
   // Poison the stack red zones at the entry.
   Value *ShadowBase =
       ASan.memToShadow(LocalStackBase, IRB, kSpirOffloadPrivateAS);
+
+  // FIXME: For device sanitizer, we always cleanup shadow memory before using
+  // it. So, unpoison stack before ret instructions is unnecessary.
+  if (TargetTriple.isSPIROrSPIRV()) {
+    SmallVector<uint8_t, 64> ShadowMask(ShadowAfterScope.size(), 1);
+    SmallVector<uint8_t, 64> ShadowBytes(ShadowAfterScope.size(), 0);
+    copyToShadow(ShadowMask, ShadowBytes, IRB, ShadowBase, true);
+  }
+
   // As mask we must use most poisoned case: red zones and after scope.
   // As bytes we can use either the same or just red zones only.
   copyToShadow(ShadowAfterScope, ShadowAfterScope, IRB, ShadowBase,

llvm/test/Instrumentation/AddressSanitizer/SPIRV/instrument_private_address_space.ll

@@ -21,15 +21,16 @@ define spir_kernel void @kernel() #0 {
 entry:
   %p.i = alloca [4 x i32], align 4
   ; CHECK: %shadow_ptr = call i64 @__asan_mem_to_shadow(i64 %0, i32 0)
-  ; CHECK: call void @__asan_set_shadow_private(i64 %4, i64 2, i8 -15)
-  ; CHECK: call void @__asan_set_shadow_private(i64 %5, i64 1, i8 -13)
+  ; CHECK: call void @__asan_set_shadow_private(i64 %4, i64 4, i8 0)
+  ; CHECK: call void @__asan_set_shadow_private(i64 %5, i64 2, i8 -15)
+  ; CHECK: call void @__asan_set_shadow_private(i64 %6, i64 1, i8 -13)
   call void @llvm.lifetime.start.p0(i64 16, ptr nonnull %p.i)
   call void @llvm.memcpy.p0.p1.i64(ptr align 4 %p.i, ptr addrspace(1) align 4 @__const._ZZZ4mainENKUlRN4sycl3_V17handlerEE_clES2_ENKUlvE_clEv.p, i64 16, i1 false)
   %arraydecay.i = getelementptr inbounds [4 x i32], ptr %p.i, i64 0, i64 0
   %0 = addrspacecast ptr %arraydecay.i to ptr addrspace(4)
   %call.i = call spir_func i32 @_Z3fooPii(ptr addrspace(4) %0)
-  ; CHECK: call void @__asan_set_shadow_private(i64 %7, i64 2, i8 0)
-  ; CHECK: call void @__asan_set_shadow_private(i64 %8, i64 1, i8 0)
+  ; CHECK: call void @__asan_set_shadow_private(i64 %8, i64 2, i8 0)
+  ; CHECK: call void @__asan_set_shadow_private(i64 %9, i64 1, i8 0)
   ret void
 }