[SPIR-V] Improve portability of the code (#123584)

Adding SPIRV to LLVM_ALL_TARGETS
(#119653) revealed a series of
minor compilation problems and sanitizer complaints. This PR is to
address the problem.

Author: VyacheslavLevytskyy

llvm/lib/Target/SPIRV/SPIRVBuiltins.cpp

@@ -535,15 +535,15 @@ extern Register insertAssignInstr(Register Reg, Type *Ty, SPIRVType *SpirvTy,
 static SPIRV::MemorySemantics::MemorySemantics
 getSPIRVMemSemantics(std::memory_order MemOrder) {
   switch (MemOrder) {
-  case std::memory_order::memory_order_relaxed:
+  case std::memory_order_relaxed:
     return SPIRV::MemorySemantics::None;
-  case std::memory_order::memory_order_acquire:
+  case std::memory_order_acquire:
     return SPIRV::MemorySemantics::Acquire;
-  case std::memory_order::memory_order_release:
+  case std::memory_order_release:
     return SPIRV::MemorySemantics::Release;
-  case std::memory_order::memory_order_acq_rel:
+  case std::memory_order_acq_rel:
     return SPIRV::MemorySemantics::AcquireRelease;
-  case std::memory_order::memory_order_seq_cst:
+  case std::memory_order_seq_cst:
     return SPIRV::MemorySemantics::SequentiallyConsistent;
   default:
     report_fatal_error("Unknown CL memory scope");

llvm/lib/Target/SPIRV/SPIRVPrepareFunctions.cpp

@@ -22,6 +22,7 @@
 #include "SPIRVSubtarget.h"
 #include "SPIRVTargetMachine.h"
 #include "SPIRVUtils.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/CodeGen/IntrinsicLowering.h"
 #include "llvm/IR/IRBuilder.h"
@@ -30,7 +31,6 @@
 #include "llvm/IR/IntrinsicsSPIRV.h"
 #include "llvm/Transforms/Utils/Cloning.h"
 #include "llvm/Transforms/Utils/LowerMemIntrinsics.h"
-#include <charconv>
 #include <regex>
 
 using namespace llvm;
@@ -228,9 +228,7 @@ static SmallVector<Metadata *> parseAnnotation(Value *I,
         } else {
           MDsItem.push_back(MDString::get(Ctx, Item));
         }
-      } else if (int32_t Num;
-                 std::from_chars(Item.data(), Item.data() + Item.size(), Num)
-                     .ec == std::errc{}) {
+      } else if (int32_t Num; llvm::to_integer(StringRef(Item), Num, 10)) {
         MDsItem.push_back(
             ConstantAsMetadata::get(ConstantInt::get(Int32Ty, Num)));
       } else {

llvm/lib/Target/SPIRV/SPIRVUtils.h

@@ -22,6 +22,7 @@
 #include "llvm/IR/TypedPointerType.h"
 #include <queue>
 #include <string>
+#include <unordered_map>
 #include <unordered_set>
 
 namespace llvm {