Auto merge of #117947 - Dirbaio:drop-llvm-15, r=cuviper

Update the minimum external LLVM to 16.

With this change, we'll have stable support for LLVM 16 and 17.
For reference, the previous increase to LLVM 15 was #114148

[Relevant zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/riscv.20forced-atomics)

3 files changed, 1 insertions, 81 deletions

diff --git a/compiler/rustc_llvm/llvm-wrapper/LLVMWrapper.h b/compiler/rustc_llvm/llvm-wrapper/LLVMWrapper.h
index 142384e6d0c..ad97ede8e9c 100644
--- a/compiler/rustc_llvm/llvm-wrapper/LLVMWrapper.h
+++ b/compiler/rustc_llvm/llvm-wrapper/LLVMWrapper.h
@@ -42,11 +42,7 @@
 #include "llvm/IR/IRPrintingPasses.h"
 #include "llvm/Linker/Linker.h"
 
-#if LLVM_VERSION_GE(16, 0)
 #include "llvm/TargetParser/Triple.h"
-#else
-#include "llvm/ADT/Triple.h"
-#endif
 
 extern "C" void LLVMRustSetLastError(const char *);
 
diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
index d2cd79b456a..7f033265136 100644
--- a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
@@ -204,11 +204,7 @@ enum class LLVMRustCodeModel {
   None,
 };
 
-#if LLVM_VERSION_LT(16, 0)
-static Optional<CodeModel::Model>
-#else
 static std::optional<CodeModel::Model>
-#endif
 fromRust(LLVMRustCodeModel Model) {
   switch (Model) {
   case LLVMRustCodeModel::Tiny:
@@ -222,11 +218,7 @@ fromRust(LLVMRustCodeModel Model) {
   case LLVMRustCodeModel::Large:
     return CodeModel::Large;
   case LLVMRustCodeModel::None:
-#if LLVM_VERSION_LT(16, 0)
-    return None;
-#else
     return std::nullopt;
-#endif
   default:
     report_fatal_error("Bad CodeModel.");
   }
@@ -452,7 +444,6 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
   if (OutputObjFile) {
       Options.ObjectFilenameForDebug = OutputObjFile;
   }
-#if LLVM_VERSION_GE(16, 0)
   if (!strcmp("zlib", DebugInfoCompression) && llvm::compression::zlib::isAvailable()) {
     Options.CompressDebugSections = DebugCompressionType::Zlib;
   } else if (!strcmp("zstd", DebugInfoCompression) && llvm::compression::zstd::isAvailable()) {
@@ -460,7 +451,6 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
   } else if (!strcmp("none", DebugInfoCompression)) {
     Options.CompressDebugSections = DebugCompressionType::None;
   }
-#endif
 
   Options.RelaxELFRelocations = RelaxELFRelocations;
   Options.UseInitArray = UseInitArray;
@@ -734,22 +724,14 @@ LLVMRustOptimize(
   bool DebugPassManager = false;
 
   PassInstrumentationCallbacks PIC;
-#if LLVM_VERSION_LT(16, 0)
-  StandardInstrumentations SI(DebugPassManager);
-#else
   StandardInstrumentations SI(TheModule->getContext(), DebugPassManager);
-#endif
   SI.registerCallbacks(PIC);
 
   if (LlvmSelfProfiler){
     LLVMSelfProfileInitializeCallbacks(PIC,LlvmSelfProfiler,BeforePassCallback,AfterPassCallback);
   }
 
-#if LLVM_VERSION_LT(16, 0)
-  Optional<PGOOptions> PGOOpt;
-#else
   std::optional<PGOOptions> PGOOpt;
-#endif
 #if LLVM_VERSION_GE(17, 0)
   auto FS = vfs::getRealFileSystem();
 #endif
@@ -882,12 +864,7 @@ LLVMRustOptimize(
           /*EagerChecks=*/true);
       OptimizerLastEPCallbacks.push_back(
         [Options](ModulePassManager &MPM, OptimizationLevel Level) {
-#if LLVM_VERSION_LT(16, 0)
-          MPM.addPass(ModuleMemorySanitizerPass(Options));
-          MPM.addPass(createModuleToFunctionPassAdaptor(MemorySanitizerPass(Options)));
-#else
           MPM.addPass(MemorySanitizerPass(Options));
-#endif
         }
       );
     }
@@ -912,11 +889,7 @@ LLVMRustOptimize(
             /*UseAfterScope=*/true,
             AsanDetectStackUseAfterReturnMode::Runtime,
           };
-#if LLVM_VERSION_LT(16, 0)
-          MPM.addPass(ModuleAddressSanitizerPass(opts));
-#else
           MPM.addPass(AddressSanitizerPass(opts));
-#endif
         }
       );
     }
diff --git a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
index 7ada2eff593..bf870e28acd 100644
--- a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
@@ -14,18 +14,13 @@
 #include "llvm/Remarks/RemarkSerializer.h"
 #include "llvm/Remarks/RemarkFormat.h"
 #include "llvm/Support/ToolOutputFile.h"
-#if LLVM_VERSION_GE(16, 0)
 #include "llvm/Support/ModRef.h"
-#endif
 #include "llvm/Object/Archive.h"
 #include "llvm/Object/COFFImportFile.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Pass.h"
 #include "llvm/Bitcode/BitcodeWriter.h"
 #include "llvm/Support/Signals.h"
-#if LLVM_VERSION_LT(16, 0)
-#include "llvm/ADT/Optional.h"
-#endif
 
 #include <iostream>
 
@@ -347,13 +342,7 @@ extern "C" LLVMAttributeRef LLVMRustCreateUWTableAttr(LLVMContextRef C, bool Asy
 }
 
 extern "C" LLVMAttributeRef LLVMRustCreateAllocSizeAttr(LLVMContextRef C, uint32_t ElementSizeArg) {
-  return wrap(Attribute::getWithAllocSizeArgs(*unwrap(C), ElementSizeArg,
-#if LLVM_VERSION_LT(16, 0)
-                                              None
-#else
-                                              std::nullopt
-#endif
-                                              ));
+  return wrap(Attribute::getWithAllocSizeArgs(*unwrap(C), ElementSizeArg, std::nullopt));
 }
 
 // These values **must** match ffi::AllocKindFlags.
@@ -416,7 +405,6 @@ enum class LLVMRustMemoryEffects {
 
 extern "C" LLVMAttributeRef LLVMRustCreateMemoryEffectsAttr(LLVMContextRef C,
                                                             LLVMRustMemoryEffects Effects) {
-#if LLVM_VERSION_GE(16, 0)
   switch (Effects) {
     case LLVMRustMemoryEffects::None:
       return wrap(Attribute::getWithMemoryEffects(*unwrap(C), MemoryEffects::none()));
@@ -428,18 +416,6 @@ extern "C" LLVMAttributeRef LLVMRustCreateMemoryEffectsAttr(LLVMContextRef C,
     default:
       report_fatal_error("bad MemoryEffects.");
   }
-#else
-  switch (Effects) {
-    case LLVMRustMemoryEffects::None:
-      return wrap(Attribute::get(*unwrap(C), Attribute::ReadNone));
-    case LLVMRustMemoryEffects::ReadOnly:
-      return wrap(Attribute::get(*unwrap(C), Attribute::ReadOnly));
-    case LLVMRustMemoryEffects::InaccessibleMemOnly:
-      return wrap(Attribute::get(*unwrap(C), Attribute::InaccessibleMemOnly));
-    default:
-      report_fatal_error("bad MemoryEffects.");
-  }
-#endif
 }
 
 // Enable a fast-math flag
@@ -726,18 +702,10 @@ enum class LLVMRustChecksumKind {
   SHA256,
 };
 
-#if LLVM_VERSION_LT(16, 0)
-static Optional<DIFile::ChecksumKind> fromRust(LLVMRustChecksumKind Kind) {
-#else
 static std::optional<DIFile::ChecksumKind> fromRust(LLVMRustChecksumKind Kind) {
-#endif
   switch (Kind) {
   case LLVMRustChecksumKind::None:
-#if LLVM_VERSION_LT(16, 0)
-    return None;
-#else
     return std::nullopt;
-#endif
   case LLVMRustChecksumKind::MD5:
     return DIFile::ChecksumKind::CSK_MD5;
   case LLVMRustChecksumKind::SHA1:
@@ -810,17 +778,8 @@ extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateFile(
     const char *Directory, size_t DirectoryLen, LLVMRustChecksumKind CSKind,
     const char *Checksum, size_t ChecksumLen) {
 
-#if LLVM_VERSION_LT(16, 0)
-  Optional<DIFile::ChecksumKind> llvmCSKind = fromRust(CSKind);
-#else
   std::optional<DIFile::ChecksumKind> llvmCSKind = fromRust(CSKind);
-#endif
-
-#if LLVM_VERSION_LT(16, 0)
-  Optional<DIFile::ChecksumInfo<StringRef>> CSInfo{};
-#else
   std::optional<DIFile::ChecksumInfo<StringRef>> CSInfo{};
-#endif
   if (llvmCSKind)
     CSInfo.emplace(*llvmCSKind, StringRef{Checksum, ChecksumLen});
   return wrap(Builder->createFile(StringRef(Filename, FilenameLen),
@@ -2053,17 +2012,9 @@ extern "C" bool LLVMRustIsNonGVFunctionPointerTy(LLVMValueRef V) {
 }
 
 extern "C" bool LLVMRustLLVMHasZlibCompressionForDebugSymbols() {
-#if LLVM_VERSION_GE(16, 0)
   return llvm::compression::zlib::isAvailable();
-#else
-  return false;
-#endif
 }
 
 extern "C" bool LLVMRustLLVMHasZstdCompressionForDebugSymbols() {
-#if LLVM_VERSION_GE(16, 0)
   return llvm::compression::zstd::isAvailable();
-#else
-  return false;
-#endif
 }