[Remarks][Driver] Ask for line tables when remarks are enabled

[thegameg]

Summary

Serialized remarks contain debug locations for each remark, by storing a file path, a line, and a column.

Also, remarks support being embedded in a .dSYM bundle using a separate section in object files, that is found by dsymutil through the debug map.

In order for tools to map addresses to source and display remarks in the source, we need line tables, and in order for dsymutil to find the object files containing the remark section, we need to keep the debug map around.

[aprantl]

clang/lib/Driver/ToolChains/Clang.cpp

3724

DebugInfoKind < codegenoptions::DebugDirectivesOnly
lest someone will sneak in another enumerator without updating this code.

clang/lib/Driver/ToolChains/Clang.cpp

static void RenderDebugOptions(const ToolChain &TC, const Driver &D,
   if (Args.hasFlag(options::OPT_gno_inline_line_tables,
                    options::OPT_ginline_line_tables, false)) {
     CmdArgs.push_back("-gno-inline-line-tables");
   }
 
   // Adjust the debug info kind for the given toolchain.
   TC.adjustDebugInfoKind(DebugInfoKind, Args);
 
+  // When emitting remarks, we need at least debug lines in the output.
+  if (shouldEmitRemarks(Args) &&
+      DebugInfoKind <= codegenoptions::DebugDirectivesOnly)
+    DebugInfoKind = codegenoptions::DebugLineTablesOnly;
+
   RenderDebugEnablingArgs(Args, CmdArgs, DebugInfoKind, DWARFVersion,
                           DebuggerTuning);
 
   // -fdebug-macro turns on macro debug info generation.
   if (Args.hasFlag(options::OPT_fdebug_macro, options::OPT_fno_debug_macro,
                    false))
     if (checkDebugInfoOption(Args.getLastArg(options::OPT_fdebug_macro), Args,
                              D, TC))

clang/test/Driver/debug-options.c

 // RUN: %clang -### -c -g %s -target armv7-apple-ios8.0 2>&1 \
 // RUN:             | FileCheck -check-prefix=G_ONLY_DWARF2 %s
 // RUN: %clang -### -c -g %s -target armv7k-apple-watchos 2>&1 \
 // RUN:             | FileCheck -check-prefix=G_STANDALONE \
 // RUN:                         -check-prefix=G_DWARF4 %s
 // RUN: %clang -### -c -g %s -target arm64-apple-tvos9.0 2>&1 \
 // RUN:             | FileCheck -check-prefix=G_STANDALONE \
 // RUN:                         -check-prefix=G_DWARF4 %s
+// RUN: %clang -### -c -fsave-optimization-record %s \
+// RUN:        -target x86_64-apple-darwin 2>&1 \
+// RUN:             | FileCheck -check-prefix=GLTO_ONLY %s
+// RUN: %clang -### -c -g -fsave-optimization-record %s \
+// RUN:        -target x86_64-apple-darwin 2>&1 \
+// RUN:             | FileCheck -check-prefix=G_STANDALONE %s
 
 // FreeBSD.
 // RUN: %clang -### -c -g %s -target x86_64-pc-freebsd11.0 2>&1 \
 // RUN:             | FileCheck -check-prefix=G_GDB \
 // RUN:                         -check-prefix=G_DWARF2 %s
 // RUN: %clang -### -c -g %s -target x86_64-pc-freebsd12.0 2>&1 \
 // RUN:             | FileCheck -check-prefix=G_GDB \
 // RUN:                         -check-prefix=G_DWARF4 %s