Rollup merge of #66973 - cuviper:min-llvm7, r=alexcrichton

Update the minimum external LLVM to 7

LLVM 7 is over a year old, which should be plenty for compatibility. The
last LLVM 6 holdout was llvm-emscripten, which went away in #65501.

I've also included a fix for LLVM 8 lacking `MemorySanitizerOptions`,
which was broken by #66522.

src/rustllvm/PassWrapper.cpp

@@ -101,11 +101,13 @@ extern "C" LLVMPassRef LLVMRustCreateModuleAddressSanitizerPass(bool Recover) {
 }
 
 extern "C" LLVMPassRef LLVMRustCreateMemorySanitizerPass(int TrackOrigins, bool Recover) {
-#if LLVM_VERSION_GE(8, 0)
+#if LLVM_VERSION_GE(9, 0)
   const bool CompileKernel = false;
 
   return wrap(createMemorySanitizerLegacyPassPass(
       MemorySanitizerOptions{TrackOrigins, Recover, CompileKernel}));
+#elif LLVM_VERSION_GE(8, 0)
+  return wrap(createMemorySanitizerLegacyPassPass(TrackOrigins, Recover));
 #else
   return wrap(createMemorySanitizerPass(TrackOrigins, Recover));
 #endif
@@ -451,9 +453,7 @@ extern "C" void LLVMRustConfigurePassManagerBuilder(
     LLVMPassManagerBuilderRef PMBR, LLVMRustCodeGenOptLevel OptLevel,
     bool MergeFunctions, bool SLPVectorize, bool LoopVectorize, bool PrepareForThinLTO,
     const char* PGOGenPath, const char* PGOUsePath) {
-#if LLVM_VERSION_GE(7, 0)
   unwrap(PMBR)->MergeFunctions = MergeFunctions;
-#endif
   unwrap(PMBR)->SLPVectorize = SLPVectorize;
   unwrap(PMBR)->OptLevel = fromRust(OptLevel);
   unwrap(PMBR)->LoopVectorize = LoopVectorize;
@@ -560,12 +560,8 @@ LLVMRustWriteOutputFile(LLVMTargetMachineRef Target, LLVMPassManagerRef PMR,
     return LLVMRustResult::Failure;
   }
 
-#if LLVM_VERSION_GE(7, 0)
   buffer_ostream BOS(OS);
   unwrap(Target)->addPassesToEmitFile(*PM, BOS, nullptr, FileType, false);
-#else
-  unwrap(Target)->addPassesToEmitFile(*PM, OS, FileType, false);
-#endif
   PM->run(*unwrap(M));
 
   // Apparently `addPassesToEmitFile` adds a pointer to our on-the-stack output
@@ -849,9 +845,7 @@ struct LLVMRustThinLTOData {
   StringMap<FunctionImporter::ExportSetTy> ExportLists;
   StringMap<GVSummaryMapTy> ModuleToDefinedGVSummaries;
 
-#if LLVM_VERSION_GE(7, 0)
   LLVMRustThinLTOData() : Index(/* HaveGVs = */ false) {}
-#endif
 };
 
 // Just an argument to the `LLVMRustCreateThinLTOData` function below.
@@ -922,7 +916,6 @@ LLVMRustCreateThinLTOData(LLVMRustThinLTOModule *modules,
   // combined index
   //
   // This is copied from `lib/LTO/ThinLTOCodeGenerator.cpp`
-#if LLVM_VERSION_GE(7, 0)
   auto deadIsPrevailing = [&](GlobalValue::GUID G) {
     return PrevailingType::Unknown;
   };
@@ -934,9 +927,6 @@ LLVMRustCreateThinLTOData(LLVMRustThinLTOModule *modules,
                                   deadIsPrevailing, /* ImportEnabled = */ false);
 #else
   computeDeadSymbols(Ret->Index, Ret->GUIDPreservedSymbols, deadIsPrevailing);
-#endif
-#else
-  computeDeadSymbols(Ret->Index, Ret->GUIDPreservedSymbols);
 #endif
   ComputeCrossModuleImport(
     Ret->Index,

src/rustllvm/RustWrapper.cpp

@@ -88,11 +88,7 @@ extern "C" char *LLVMRustGetLastError(void) {
 }
 
 extern "C" unsigned int LLVMRustGetInstructionCount(LLVMModuleRef M) {
-#if LLVM_VERSION_GE(7, 0)
   return unwrap(M)->getInstructionCount();
-#else
-  report_fatal_error("Module::getInstructionCount not available before LLVM 7");
-#endif
 }
 
 extern "C" void LLVMRustSetLastError(const char *Err) {
@@ -761,14 +757,10 @@ extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateVariantPart(
     LLVMMetadataRef File, unsigned LineNumber, uint64_t SizeInBits,
     uint32_t AlignInBits, LLVMRustDIFlags Flags, LLVMMetadataRef Discriminator,
     LLVMMetadataRef Elements, const char *UniqueId) {
-#if LLVM_VERSION_GE(7, 0)
   return wrap(Builder->createVariantPart(
       unwrapDI<DIDescriptor>(Scope), Name, unwrapDI<DIFile>(File), LineNumber,
       SizeInBits, AlignInBits, fromRust(Flags), unwrapDI<DIDerivedType>(Discriminator),
       DINodeArray(unwrapDI<MDTuple>(Elements)), UniqueId));
-#else
-  abort();
-#endif
 }
 
 extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateMemberType(
@@ -787,7 +779,6 @@ extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateVariantMemberType(
     const char *Name, LLVMMetadataRef File, unsigned LineNo, uint64_t SizeInBits,
     uint32_t AlignInBits, uint64_t OffsetInBits, LLVMValueRef Discriminant,
     LLVMRustDIFlags Flags, LLVMMetadataRef Ty) {
-#if LLVM_VERSION_GE(7, 0)
   llvm::ConstantInt* D = nullptr;
   if (Discriminant) {
     D = unwrap<llvm::ConstantInt>(Discriminant);
@@ -796,12 +787,6 @@ extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateVariantMemberType(
                                                unwrapDI<DIFile>(File), LineNo,
                                                SizeInBits, AlignInBits, OffsetInBits, D,
                                                fromRust(Flags), unwrapDI<DIType>(Ty)));
-#else
-  return wrap(Builder->createMemberType(unwrapDI<DIDescriptor>(Scope), Name,
-                                        unwrapDI<DIFile>(File), LineNo,
-                                        SizeInBits, AlignInBits, OffsetInBits,
-                                        fromRust(Flags), unwrapDI<DIType>(Ty)));
-#endif
 }
 
 extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateLexicalBlock(
@@ -911,18 +896,10 @@ extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateEnumerationType(
     LLVMMetadataRef File, unsigned LineNumber, uint64_t SizeInBits,
     uint32_t AlignInBits, LLVMMetadataRef Elements,
     LLVMMetadataRef ClassTy, bool IsScoped) {
-#if LLVM_VERSION_GE(7, 0)
   return wrap(Builder->createEnumerationType(
       unwrapDI<DIDescriptor>(Scope), Name, unwrapDI<DIFile>(File), LineNumber,
       SizeInBits, AlignInBits, DINodeArray(unwrapDI<MDTuple>(Elements)),
       unwrapDI<DIType>(ClassTy), "", IsScoped));
-#else
-  // Ignore IsScoped on older LLVM.
-  return wrap(Builder->createEnumerationType(
-      unwrapDI<DIDescriptor>(Scope), Name, unwrapDI<DIFile>(File), LineNumber,
-      SizeInBits, AlignInBits, DINodeArray(unwrapDI<MDTuple>(Elements)),
-      unwrapDI<DIType>(ClassTy), ""));
-#endif
 }
 
 extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateUnionType(
@@ -1275,34 +1252,20 @@ extern "C" LLVMValueRef LLVMRustBuildMemCpy(LLVMBuilderRef B,
                                             LLVMValueRef Dst, unsigned DstAlign,
                                             LLVMValueRef Src, unsigned SrcAlign,
                                             LLVMValueRef Size, bool IsVolatile) {
-#if LLVM_VERSION_GE(7, 0)
   return wrap(unwrap(B)->CreateMemCpy(
       unwrap(Dst), DstAlign,
       unwrap(Src), SrcAlign,
       unwrap(Size), IsVolatile));
-#else
-  unsigned Align = std::min(DstAlign, SrcAlign);
-  return wrap(unwrap(B)->CreateMemCpy(
-      unwrap(Dst), unwrap(Src),
-      unwrap(Size), Align, IsVolatile));
-#endif
 }
 
 extern "C" LLVMValueRef LLVMRustBuildMemMove(LLVMBuilderRef B,
                                              LLVMValueRef Dst, unsigned DstAlign,
                                              LLVMValueRef Src, unsigned SrcAlign,
                                              LLVMValueRef Size, bool IsVolatile) {
-#if LLVM_VERSION_GE(7, 0)
   return wrap(unwrap(B)->CreateMemMove(
       unwrap(Dst), DstAlign,
       unwrap(Src), SrcAlign,
       unwrap(Size), IsVolatile));
-#else
-  unsigned Align = std::min(DstAlign, SrcAlign);
-  return wrap(unwrap(B)->CreateMemMove(
-      unwrap(Dst), unwrap(Src),
-      unwrap(Size), Align, IsVolatile));
-#endif
 }
 
 extern "C" LLVMValueRef