[AsmPrinter] fix -disable-debug-info option

This option was in a rather convoluted place, causing global parameters
to be set in awkward and undesirable ways to try to account for it
indirectly. Add tests for the -disable-debug-info option and ensure we
don't print unintended markers from unintended places.

Reviewed By: dstenb

Differential Revision: https://reviews.llvm.org/D91083

Author: vtjnash

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -131,6 +131,11 @@ using namespace llvm;
 
 #define DEBUG_TYPE "asm-printer"
 
+// FIXME: this option currently only applies to DWARF, and not CodeView, tables
+static cl::opt<bool>
+    DisableDebugInfoPrinting("disable-debug-info-print", cl::Hidden,
+                             cl::desc("Disable debug info printing"));
+
 static const char *const DWARFGroupName = "dwarf";
 static const char *const DWARFGroupDescription = "DWARF Emission";
 static const char *const DbgTimerName = "emit";
@@ -232,9 +237,11 @@ void AsmPrinter::EmitToStreamer(MCStreamer &S, const MCInst &Inst) {
 }
 
 void AsmPrinter::emitInitialRawDwarfLocDirective(const MachineFunction &MF) {
-  assert(DD && "Dwarf debug file is not defined.");
-  assert(OutStreamer->hasRawTextSupport() && "Expected assembly output mode.");
-  (void)DD->emitInitialLocDirective(MF, /*CUID=*/0);
+  if (DD) {
+    assert(OutStreamer->hasRawTextSupport() &&
+           "Expected assembly output mode.");
+    (void)DD->emitInitialLocDirective(MF, /*CUID=*/0);
+  }
 }
 
 /// getCurrentSection() - Return the current section we are emitting to.
@@ -262,6 +269,9 @@ bool AsmPrinter::doInitialization(Module &M) {
 
   OutStreamer->InitSections(false);
 
+  if (DisableDebugInfoPrinting)
+    MMI->setDebugInfoAvailability(false);
+
   // Emit the version-min deployment target directive if needed.
   //
   // FIXME: If we end up with a collection of these sorts of Darwin-specific
@@ -314,10 +324,12 @@ bool AsmPrinter::doInitialization(Module &M) {
                             CodeViewLineTablesGroupDescription);
     }
     if (!EmitCodeView || M.getDwarfVersion()) {
-      DD = new DwarfDebug(this);
-      Handlers.emplace_back(std::unique_ptr<DwarfDebug>(DD), DbgTimerName,
-                            DbgTimerDescription, DWARFGroupName,
-                            DWARFGroupDescription);
+      if (!DisableDebugInfoPrinting) {
+        DD = new DwarfDebug(this);
+        Handlers.emplace_back(std::unique_ptr<DwarfDebug>(DD), DbgTimerName,
+                              DbgTimerDescription, DWARFGroupName,
+                              DWARFGroupDescription);
+      }
     }
   }
 

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -67,10 +67,6 @@ using namespace llvm;
 
 STATISTIC(NumCSParams, "Number of dbg call site params created");
 
-static cl::opt<bool>
-DisableDebugInfoPrinting("disable-debug-info-print", cl::Hidden,
-                         cl::desc("Disable debug info printing"));
-
 static cl::opt<bool> UseDwarfRangesBaseAddressSpecifier(
     "use-dwarf-ranges-base-address-specifier", cl::Hidden,
     cl::desc("Use base address specifiers in debug_ranges"), cl::init(false));
@@ -1122,7 +1118,7 @@ sortGlobalExprs(SmallVectorImpl<DwarfCompileUnit::GlobalExpr> &GVEs) {
 void DwarfDebug::beginModule(Module *M) {
   DebugHandlerBase::beginModule(M);
 
-  if (!Asm || !MMI->hasDebugInfo() || DisableDebugInfoPrinting)
+  if (!Asm || !MMI->hasDebugInfo())
     return;
 
   unsigned NumDebugCUs = std::distance(M->debug_compile_units_begin(),
@@ -1390,9 +1386,8 @@ void DwarfDebug::endModule() {
   }
 
   // If we aren't actually generating debug info (check beginModule -
-  // conditionalized on !DisableDebugInfoPrinting and the presence of the
-  // llvm.dbg.cu metadata node)
-  if (!Asm || !MMI->hasDebugInfo() || DisableDebugInfoPrinting)
+  // conditionalized on the presence of the llvm.dbg.cu metadata node)
+  if (!Asm || !MMI->hasDebugInfo())
     return;
 
   // Finalize the debug info for the module.

llvm/test/CodeGen/Generic/disable-debug-info-print.ll

@@ -0,0 +1,52 @@
+; RUN: llc -disable-debug-info-print=true -exception-model=dwarf -o - %s | FileCheck %s
+; RUN: llc -disable-debug-info-print=true -exception-model=sjlj -o - %s | FileCheck %s --check-prefix=SJLJ-CHECK
+
+define i16 @main() nounwind !dbg !7 {
+entry:
+  ret i16 0, !dbg !9
+}
+
+define i16 @helper() !dbg !10 {
+entry:
+  ret i16 0, !dbg !11
+}
+
+
+; CHECK: .file   "disable-debug-info-print.ll"
+; CHECK: main
+; CHECK-NOT: cfi_startproc
+; CHECK-NOT: .file
+; CHECK-NOT: .loc
+; CHECK: helper
+; CHECK: cfi_startproc
+; CHECK-NOT: .file
+; CHECK-NOT: .loc
+; CHECK: cfi_endproc
+
+; SJLJ-CHECK: .file   "disable-debug-info-print.ll"
+; SJLJ-CHECK: main
+; SJLJ-CHECK-NOT: cfi_startproc
+; SJLJ-CHECK-NOT: .file
+; SJLJ-CHECK-NOT: .loc
+; SJLJ-CHECK: helper
+; SJLJ-CHECK-NOT: cfi_startproc
+; SJLJ-CHECK-NOT: .file
+; SJLJ-CHECK-NOT: .loc
+
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 12.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, enums: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "unwind-tables.c", directory: "/tmp")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 12.0.0"}
+!7 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!8 = !DISubroutineType(types: !2)
+!9 = !DILocation(line: 2, column: 3, scope: !7)
+!10 = distinct !DISubprogram(name: "helper", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!11 = !DILocation(line: 2, column: 3, scope: !10)