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

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.

Differential Revision: https://reviews.llvm.org/D71325

Author: francisvm

clang/lib/Driver/ToolChains/Clang.cpp

@@ -3717,6 +3717,11 @@ static void RenderDebugOptions(const ToolChain &TC, const Driver &D,
   // 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);
 

clang/test/Driver/debug-options.c

@@ -64,6 +64,12 @@
 // 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 \