fully exploited the dropped support of LLVM 8

This commit grepped for LLVM_VERSION_GE, LLVM_VERSION_LT, get_major_version and
min-llvm-version and statically evaluated every expression possible
(and sensible) assuming that the LLVM version is >=9 now

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -16,9 +16,7 @@
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Object/IRObjectFile.h"
 #include "llvm/Passes/PassBuilder.h"
-#if LLVM_VERSION_GE(9, 0)
 #include "llvm/Passes/StandardInstrumentations.h"
-#endif
 #include "llvm/Support/CBindingWrapping.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Host.h"
@@ -31,15 +29,11 @@
 #include "llvm-c/Transforms/PassManagerBuilder.h"
 
 #include "llvm/Transforms/Instrumentation.h"
-#if LLVM_VERSION_GE(9, 0)
 #include "llvm/Transforms/Instrumentation/AddressSanitizer.h"
 #include "llvm/Support/TimeProfiler.h"
-#endif
 #include "llvm/Transforms/Instrumentation/ThreadSanitizer.h"
 #include "llvm/Transforms/Instrumentation/MemorySanitizer.h"
-#if LLVM_VERSION_GE(9, 0)
 #include "llvm/Transforms/Utils/CanonicalizeAliases.h"
-#endif
 #include "llvm/Transforms/Utils/NameAnonGlobals.h"
 
 using namespace llvm;
@@ -73,20 +67,18 @@ extern "C" void LLVMTimeTraceProfilerInitialize() {
   timeTraceProfilerInitialize(
       /* TimeTraceGranularity */ 0,
       /* ProcName */ "rustc");
-#elif LLVM_VERSION_GE(9, 0)
+#else
   timeTraceProfilerInitialize();
 #endif
 }
 
 extern "C" void LLVMTimeTraceProfilerFinish(const char* FileName) {
-#if LLVM_VERSION_GE(9, 0)
   StringRef FN(FileName);
   std::error_code EC;
   raw_fd_ostream OS(FN, EC, sys::fs::CD_CreateAlways);
 
   timeTraceProfilerWrite(OS);
   timeTraceProfilerCleanup();
-#endif
 }
 
 enum class LLVMRustPassKind {
@@ -127,22 +119,14 @@ extern "C" LLVMPassRef LLVMRustCreateAddressSanitizerFunctionPass(bool Recover)
 extern "C" LLVMPassRef LLVMRustCreateModuleAddressSanitizerPass(bool Recover) {
   const bool CompileKernel = false;
 
-#if LLVM_VERSION_GE(9, 0)
   return wrap(createModuleAddressSanitizerLegacyPassPass(CompileKernel, Recover));
-#else
-  return wrap(createAddressSanitizerModulePass(CompileKernel, Recover));
-#endif
 }
 
 extern "C" LLVMPassRef LLVMRustCreateMemorySanitizerPass(int TrackOrigins, bool Recover) {
-#if LLVM_VERSION_GE(9, 0)
   const bool CompileKernel = false;
 
   return wrap(createMemorySanitizerLegacyPassPass(
       MemorySanitizerOptions{TrackOrigins, Recover, CompileKernel}));
-#else
-  return wrap(createMemorySanitizerLegacyPassPass(TrackOrigins, Recover));
-#endif
 }
 
 extern "C" LLVMPassRef LLVMRustCreateThreadSanitizerPass() {
@@ -657,8 +641,6 @@ extern "C" typedef void (*LLVMRustSelfProfileBeforePassCallback)(void*, // LlvmS
                                                       const char*);     // IR name
 extern "C" typedef void (*LLVMRustSelfProfileAfterPassCallback)(void*); // LlvmSelfProfiler
 
-#if LLVM_VERSION_GE(9, 0)
-
 std::string LLVMRustwrappedIrGetName(const llvm::Any &WrappedIr) {
   if (any_isa<const Module *>(WrappedIr))
     return any_cast<const Module *>(WrappedIr)->getName().str();
@@ -706,7 +688,6 @@ void LLVMSelfProfileInitializeCallbacks(
         AfterPassCallback(LlvmSelfProfiler);
       });
 }
-#endif
 
 enum class LLVMRustOptStage {
   PreLinkNoLTO,
@@ -739,7 +720,6 @@ LLVMRustOptimizeWithNewPassManager(
     void* LlvmSelfProfiler,
     LLVMRustSelfProfileBeforePassCallback BeforePassCallback,
     LLVMRustSelfProfileAfterPassCallback AfterPassCallback) {
-#if LLVM_VERSION_GE(9, 0)
   Module *TheModule = unwrap(ModuleRef);
   TargetMachine *TM = unwrap(TMRef);
   PassBuilder::OptimizationLevel OptLevel = fromRust(OptLevelRust);
@@ -970,11 +950,6 @@ LLVMRustOptimizeWithNewPassManager(
     UpgradeCallsToIntrinsic(&*I++); // must be post-increment, as we remove
 
   MPM.run(*TheModule, MAM);
-#else
-  // The new pass manager has been available for a long time,
-  // but we don't bother supporting it on old LLVM versions.
-  report_fatal_error("New pass manager only supported since LLVM 9");
-#endif
 }
 
 // Callback to demangle function name
@@ -1325,12 +1300,9 @@ LLVMRustCreateThinLTOData(LLVMRustThinLTOModule *modules,
                               GlobalValue::LinkageTypes NewLinkage) {
     Ret->ResolvedODR[ModuleIdentifier][GUID] = NewLinkage;
   };
-#if LLVM_VERSION_GE(9, 0)
+
   thinLTOResolvePrevailingInIndex(Ret->Index, isPrevailing, recordNewLinkage,
                                   Ret->GUIDPreservedSymbols);
-#else
-  thinLTOResolvePrevailingInIndex(Ret->Index, isPrevailing, recordNewLinkage);
-#endif
 
   // Here we calculate an `ExportedGUIDs` set for use in the `isExported`
   // callback below. This callback below will dictate the linkage for all

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -124,9 +124,7 @@ extern "C" LLVMValueRef LLVMRustGetOrInsertFunction(LLVMModuleRef M,
   return wrap(unwrap(M)
                   ->getOrInsertFunction(StringRef(Name, NameLen),
                                         unwrap<FunctionType>(FunctionTy))
-#if LLVM_VERSION_GE(9, 0)
                   .getCallee()
-#endif
   );
 }
 
@@ -251,11 +249,7 @@ extern "C" void LLVMRustAddDereferenceableOrNullCallSiteAttr(LLVMValueRef Instr,
 extern "C" void LLVMRustAddByValCallSiteAttr(LLVMValueRef Instr, unsigned Index,
                                              LLVMTypeRef Ty) {
   CallBase *Call = unwrap<CallBase>(Instr);
-#if LLVM_VERSION_GE(9, 0)
   Attribute Attr = Attribute::getWithByValType(Call->getContext(), unwrap(Ty));
-#else
-  Attribute Attr = Attribute::get(Call->getContext(), Attribute::ByVal);
-#endif
   Call->addAttribute(Index, Attr);
 }
 
@@ -296,11 +290,7 @@ extern "C" void LLVMRustAddDereferenceableOrNullAttr(LLVMValueRef Fn,
 extern "C" void LLVMRustAddByValAttr(LLVMValueRef Fn, unsigned Index,
                                      LLVMTypeRef Ty) {
   Function *F = unwrap<Function>(Fn);
-#if LLVM_VERSION_GE(9, 0)
   Attribute Attr = Attribute::getWithByValType(F->getContext(), unwrap(Ty));
-#else
-  Attribute Attr = Attribute::get(F->getContext(), Attribute::ByVal);
-#endif
   F->addAttribute(Index, Attr);
 }
 
@@ -616,11 +606,9 @@ static DISubprogram::DISPFlags fromRust(LLVMRustDISPFlags SPFlags) {
   if (isSet(SPFlags & LLVMRustDISPFlags::SPFlagOptimized)) {
     Result |= DISubprogram::DISPFlags::SPFlagOptimized;
   }
-#if LLVM_VERSION_GE(9, 0)
   if (isSet(SPFlags & LLVMRustDISPFlags::SPFlagMainSubprogram)) {
     Result |= DISubprogram::DISPFlags::SPFlagMainSubprogram;
   }
-#endif
 
   return Result;
 }
@@ -744,10 +732,6 @@ extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateFunction(
       DITemplateParameterArray(unwrap<MDTuple>(TParam));
   DISubprogram::DISPFlags llvmSPFlags = fromRust(SPFlags);
   DINode::DIFlags llvmFlags = fromRust(Flags);
-#if LLVM_VERSION_LT(9, 0)
-  if (isSet(SPFlags & LLVMRustDISPFlags::SPFlagMainSubprogram))
-    llvmFlags |= DINode::DIFlags::FlagMainSubprogram;
-#endif
   DISubprogram *Sub = Builder->createFunction(
       unwrapDI<DIScope>(Scope),
       StringRef(Name, NameLen),