From a3036b386383f1c1e9d32c2c8dba995087959da3 Mon Sep 17 00:00:00 2001
From: Alexandre Ganea <alexandre.ganea@ubisoft.com>
Date: Mon, 10 Aug 2020 13:36:20 -0400
Subject: Re-Re-land: [CodeView] Add full repro to LF_BUILDINFO record

This patch adds the missing information to the LF_BUILDINFO record, which allows for rebuilding a .CPP without any external dependency but the .OBJ itself (other than the compiler).

Some external tools that we are using (Recode, Live++) are extracting the information to reproduce a build without any knowledge of the build system. The LF_BUILDINFO stores a full path to the compiler, the PWD (CWD at program startup), a relative or absolute path to the TU, and the full CC1 command line. The command line needs to be freestanding (not depend on any environment variables). In the same way, MSVC doesn't store the provided command-line, but an expanded version (somehow their equivalent of CC1) which is also freestanding.

For more information see PR36198 and D43002.

Differential Revision: https://reviews.llvm.org/D80833
---
 llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp | 38 +++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

(limited to 'llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp')

diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index b388e43..df29440 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -68,6 +68,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/Program.h"
 #include "llvm/Support/SMLoc.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "llvm/Target/TargetLoweringObjectFile.h"
@@ -817,6 +818,31 @@ static TypeIndex getStringIdTypeIdx(GlobalTypeTableBuilder &TypeTable,
   return TypeTable.writeLeafType(SIR);
 }
 
+static std::string flattenCommandLine(ArrayRef<const char *> Args,
+                                      StringRef MainFilename) {
+  std::string FlatCmdLine;
+  raw_string_ostream OS(FlatCmdLine);
+  StringRef LastArg;
+  for (StringRef Arg : Args) {
+    if (Arg.empty())
+      continue;
+    // The command-line shall not contain the file to compile.
+    if (Arg == MainFilename && LastArg != "-main-file-name")
+      continue;
+    // Also remove the output file.
+    if (Arg == "-o" || LastArg == "-o") {
+      LastArg = Arg;
+      continue;
+    }
+    if (!LastArg.empty())
+      OS << " ";
+    llvm::sys::printArg(OS, Arg, /*Quote=*/true);
+    LastArg = Arg;
+  }
+  OS.flush();
+  return FlatCmdLine;
+}
+
 void CodeViewDebug::emitBuildInfo() {
   // First, make LF_BUILDINFO. It's a sequence of strings with various bits of
   // build info. The known prefix is:
@@ -837,8 +863,16 @@ void CodeViewDebug::emitBuildInfo() {
       getStringIdTypeIdx(TypeTable, MainSourceFile->getDirectory());
   BuildInfoArgs[BuildInfoRecord::SourceFile] =
       getStringIdTypeIdx(TypeTable, MainSourceFile->getFilename());
-  // FIXME: Path to compiler and command line. PDB is intentionally blank unless
-  // we implement /Zi type servers.
+  // FIXME: PDB is intentionally blank unless we implement /Zi type servers.
+  BuildInfoArgs[BuildInfoRecord::TypeServerPDB] =
+      getStringIdTypeIdx(TypeTable, "");
+  if (Asm->TM.Options.MCOptions.Argv0 != nullptr) {
+    BuildInfoArgs[BuildInfoRecord::BuildTool] =
+        getStringIdTypeIdx(TypeTable, Asm->TM.Options.MCOptions.Argv0);
+    BuildInfoArgs[BuildInfoRecord::CommandLine] = getStringIdTypeIdx(
+        TypeTable, flattenCommandLine(Asm->TM.Options.MCOptions.CommandLineArgs,
+                                      MainSourceFile->getFilename()));
+  }
   BuildInfoRecord BIR(BuildInfoArgs);
   TypeIndex BuildInfoIndex = TypeTable.writeLeafType(BIR);
 
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