Rollup merge of #71490 - petrochenkov:passcheck2, r=davidtwco

Cleanup and document `-C relocation-model`

As the title says, this is mostly a refactoring and documentation.

One potentially observable change here is that `-C relocation-model=default` now takes the default from the Rust target, rather than from the underlying LLVM target. In other words, `-C relocation-model=default` is now equivalent to not specifying the relocation model on command line at all.
Apparently no one used that option because it has other bugs as well, e.g. PIC `default` wasn't treated as PIC in some places.

1 files changed, 9 insertions, 12 deletions

diff --git a/src/rustllvm/PassWrapper.cpp b/src/rustllvm/PassWrapper.cpp
index b221c17b422..e31dd77d8af 100644
--- a/src/rustllvm/PassWrapper.cpp
+++ b/src/rustllvm/PassWrapper.cpp
@@ -346,8 +346,7 @@ static PassBuilder::OptimizationLevel fromRust(LLVMRustPassBuilderOptLevel Level
   }
 }
 
-enum class LLVMRustRelocMode {
-  Default,
+enum class LLVMRustRelocModel {
   Static,
   PIC,
   DynamicNoPic,
@@ -356,21 +355,19 @@ enum class LLVMRustRelocMode {
   ROPIRWPI,
 };
 
-static Optional<Reloc::Model> fromRust(LLVMRustRelocMode RustReloc) {
+static Reloc::Model fromRust(LLVMRustRelocModel RustReloc) {
   switch (RustReloc) {
-  case LLVMRustRelocMode::Default:
-    return None;
-  case LLVMRustRelocMode::Static:
+  case LLVMRustRelocModel::Static:
     return Reloc::Static;
-  case LLVMRustRelocMode::PIC:
+  case LLVMRustRelocModel::PIC:
     return Reloc::PIC_;
-  case LLVMRustRelocMode::DynamicNoPic:
+  case LLVMRustRelocModel::DynamicNoPic:
     return Reloc::DynamicNoPIC;
-  case LLVMRustRelocMode::ROPI:
+  case LLVMRustRelocModel::ROPI:
     return Reloc::ROPI;
-  case LLVMRustRelocMode::RWPI:
+  case LLVMRustRelocModel::RWPI:
     return Reloc::RWPI;
-  case LLVMRustRelocMode::ROPIRWPI:
+  case LLVMRustRelocModel::ROPIRWPI:
     return Reloc::ROPI_RWPI;
   }
   report_fatal_error("Bad RelocModel.");
@@ -440,7 +437,7 @@ extern "C" const char* LLVMRustGetHostCPUName(size_t *len) {
 
 extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
     const char *TripleStr, const char *CPU, const char *Feature,
-    const char *ABIStr, LLVMRustCodeModel RustCM, LLVMRustRelocMode RustReloc,
+    const char *ABIStr, LLVMRustCodeModel RustCM, LLVMRustRelocModel RustReloc,
     LLVMRustCodeGenOptLevel RustOptLevel, bool UseSoftFloat,
     bool PositionIndependentExecutable, bool FunctionSections,
     bool DataSections,