[SYCL][SPIR-V] Register llvm.fpbuiltin.* in the list of known intrinsics (#19656)

Otherwise their declarations would be left in the module.

This patch is intel/llvm customization as these intrinsics are not part
of upstream llvm.

---------

Signed-off-by: Sidorov, Dmitry <dmitry.sidorov@intel.com>

Author: MrSidims

llvm-spirv/lib/SPIRV/SPIRVWriter.cpp

@@ -3984,6 +3984,17 @@ bool LLVMToSPIRVBase::isKnownIntrinsic(Intrinsic::ID Id) {
   case Intrinsic::masked_gather:
   case Intrinsic::masked_scatter:
   case Intrinsic::modf:
+  // INTEL_CUSTOMIZATION begin
+  // fpbuiltin intrinsics are not part of upstream LLVM, yet we have to register
+  // them as known.
+  case Intrinsic::fpbuiltin_fadd:
+  case Intrinsic::fpbuiltin_fsub:
+  case Intrinsic::fpbuiltin_fmul:
+  case Intrinsic::fpbuiltin_fdiv:
+  case Intrinsic::fpbuiltin_frem:
+  case Intrinsic::fpbuiltin_sqrt:
+  case Intrinsic::fpbuiltin_ldexp:
+    // INTEL_CUSTOMIZATION end
     return true;
   default:
     // Unknown intrinsics' declarations should always be translated

llvm-spirv/test/extensions/INTEL/SPV_INTEL_fp_max_error/IntelFPMaxError.ll

@@ -14,6 +14,10 @@
 ; RUN: llvm-spirv -r %t.spv -o %t.rev.bc
 ; RUN: llvm-dis < %t.rev.bc | FileCheck %s --check-prefix=CHECK-LLVM
 
+; INTEL_CUSTOMIZATION begin
+; CHECK-SPIRV-NOT: Name [[#]] "llvm.fpbuiltin."
+; INTEL_CUSTOMIZATION end
+
 ; CHECK-SPIRV: Capability FPMaxErrorINTEL
 ; CHECK-SPIRV: Extension "SPV_INTEL_fp_max_error"
 ; CHECK-SPIRV: ExtInstImport [[#OCLEXTID:]] "OpenCL.std"