[PATCH] D98183: [libLTO] Add support for -save-temps.

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
fhahn added reviewers: tejohnson, steven_wu.
Herald added subscribers: hiraditya, inglorion.
fhahn requested review of this revision.
Herald added a project: LLVM.

This patch updates LTOCodeGenerator to use `addSaveTemps` to support the
-save-temps option when using libLTO. At the moment, the save-temps
hooks are set up in parseCodeGenDebugOptions, because that's the
earliest the options have been parsed. I am not sure if there's a better
place, given the way libLTO's API is structured. At the moment, the
temporary files are created in the current working directory, because I
do not think there's a way to get the path for the final binary
up-front.

It also adds support for running the PostImportModuleHook  just before
IR optimiztions are run. At the moment, the following temporary files
are created:

- ld-temp.0.3.import.bc (before IR optimizations)
- ld-temp.0.4.opt.bc (after IR optimizations)
- ld-temp.0.5.precodegen.bc (before codegen)

Other hooks can be supported in the future, but the 3 IR files above
should be the most valuable ones when investigating mis-compiles or
crashes when doing full LTO using libLTO.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D98183

Files:
  llvm/lib/LTO/LTOCodeGenerator.cpp


Index: llvm/lib/LTO/LTOCodeGenerator.cpp
===================================================================
--- llvm/lib/LTO/LTOCodeGenerator.cpp
+++ llvm/lib/LTO/LTOCodeGenerator.cpp
@@ -119,6 +119,10 @@
     cl::Hidden);
 }
 
+static cl::opt<bool> SaveTemps(
+    "save-temps", cl::init(false),
+    cl::desc("Save temporary LTO files in the current working directory."));
+
 LTOCodeGenerator::LTOCodeGenerator(LLVMContext &Context)
     : Context(Context), MergedModule(new Module("ld-temp.o", Context)),
       TheLinker(new Linker(*MergedModule)) {
@@ -545,6 +549,9 @@
   // Add an appropriate DataLayout instance for this module...
   MergedModule->setDataLayout(TargetMach->createDataLayout());
 
+  if (Config.PostImportModuleHook)
+    Config.PostImportModuleHook(0, *MergedModule);
+
   ModuleSummaryIndex CombinedIndex(false);
   TargetMach = createTargetMachine();
   if (!opt(Config, TargetMach.get(), 0, *MergedModule, /*IsThinLTO=*/false,
@@ -606,8 +613,13 @@
       CodegenArgv.push_back(Arg.c_str());
     cl::ParseCommandLineOptions(CodegenArgv.size(), CodegenArgv.data());
   }
-}
 
+  if (SaveTemps) {
+    if (Config.addSaveTemps("ld-temp.",
+                            /* UseInputModulePath */ true))
+      errs() << "Warning: failed to set up path to save temporary files\n";
+  }
+}
 
 void LTOCodeGenerator::DiagnosticHandler(const DiagnosticInfo &DI) {
   // Map the LLVM internal diagnostic severity to the LTO diagnostic severity.


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