Fix getSPIRVBuiltin assertion failure

It's possible that the underscore-delimited postfix is not empty when we
do this check in `SPIRVToOCLBase::visitCallInst`. Should return false
instead of returning an assertion failure.

Signed-off-by: Yilong Guo <yilong.guo@intel.com>

Author: Nuullll

lib/SPIRV/SPIRVUtil.cpp

@@ -478,7 +478,8 @@ bool getSPIRVBuiltin(const std::string &OrigName, spv::BuiltIn &B) {
   SmallVector<StringRef, 2> Postfix;
   StringRef R(OrigName);
   R = dePrefixSPIRVName(R, Postfix);
-  assert(Postfix.empty() && "Invalid SPIR-V builtin Name");
+  if (!Postfix.empty())
+    return false;
   return getByName(R.str(), B);
 }
 

test/customized_func_with_underscore.ll

@@ -0,0 +1,22 @@
+; RUN: llvm-as %s -o - | llvm-spirv -o %t.spv
+; RUN: llvm-spirv -r %t.spv -o - | llvm-dis -o - | FileCheck %s
+
+target datalayout = "e-p:32:32-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024"
+target triple = "spir-unknown-unknown"
+
+; Function Attrs: nounwind readnone
+define spir_kernel void @f() #0 !kernel_arg_addr_space !0 !kernel_arg_access_qual !0 !kernel_arg_type !0 !kernel_arg_base_type !0 !kernel_arg_type_qual !0 {
+entry:
+  %0 = call spir_func i32 @_Z32__spirv_somefunc_with_underscorev()
+  ; CHECK: call spir_func i32 @_Z32__spirv_somefunc_with_underscorev()
+  %1 = call spir_func i64 @_Z28__spirv_GlobalInvocationId_xv()
+  ; CHECK: call spir_func i64 @_Z28__spirv_GlobalInvocationId_xv()
+  ret void
+}
+
+declare spir_func i32 @_Z32__spirv_somefunc_with_underscorev()
+declare spir_func i64 @_Z28__spirv_GlobalInvocationId_xv()
+
+attributes #0 = { nounwind readnone }
+
+!0 = !{}