Emit .debug_frame even when kernel has no stack call

site

Emit .debug_frame even when kernel has no stack call site so that
debugger can tell it's in entry frame and backtrace can stop.

Author: pratikashar

IGC/DebugInfo/DwarfDebug.cpp

@@ -1198,18 +1198,15 @@ void DwarfDebug::beginModule() {
   // Prime section data.
   SectionMap[Asm->GetTextSection()];
 
-  if (DwarfFrameSectionNeeded()) {
-    Asm->SwitchSection(Asm->GetDwarfFrameSection());
-    if (m_pModule->hasOrIsStackCall(*VisaDbgInfo)) {
-      // First stack call CIE is written out,
-      // next subroutine CIE if required.
-      offsetCIEStackCall = 0;
-      offsetCIESubroutine = writeStackcallCIE();
-    }
-
-    if (!m_pModule->getSubroutines(*VisaDbgInfo)->empty()) {
-      // writeSubroutineCIE();
-    }
+  Asm->SwitchSection(Asm->GetDwarfFrameSection());
+  if (m_pModule->getSubroutines(*VisaDbgInfo)->empty()) {
+    // First stack call CIE is written out,
+    // next subroutine CIE if required.
+    offsetCIEStackCall = 0;
+    offsetCIESubroutine = writeStackcallCIE();
+  } else {
+    // TODO: .debug_frame for subrotuines is currently unsupported.
+    // writeSubroutineCIE();
   }
 }
 
@@ -2408,16 +2405,14 @@ void DwarfDebug::endFunction(const Function *MF) {
   constructScopeDIE(TheCU, FnScope);
   LLVM_DEBUG(dbgs() << "[DwarfDebug] FnScope constructed ***\n");
 
-  if (DwarfFrameSectionNeeded()) {
-    Asm->SwitchSection(Asm->GetDwarfFrameSection());
-    if (m_pModule->hasOrIsStackCall(*VisaDbgInfo)) {
-      LLVM_DEBUG(dbgs() << "[DwarfDebug] writing FDEStackCall start ---\n");
-      writeFDEStackCall(m_pModule);
-      LLVM_DEBUG(dbgs() << "[DwarfDebug] writing FDEStackCall end  ***\n");
-    } else {
-      LLVM_DEBUG(dbgs() << "[DwarfDebug] FDESubproutine skipped  ***\n");
-      // writeFDESubroutine(m_pModule);
-    }
+  Asm->SwitchSection(Asm->GetDwarfFrameSection());
+  if (m_pModule->getSubroutines(*VisaDbgInfo)->empty()) {
+    LLVM_DEBUG(dbgs() << "[DwarfDebug] writing FDEStackCall start ---\n");
+    writeFDEStackCall(m_pModule);
+    LLVM_DEBUG(dbgs() << "[DwarfDebug] writing FDEStackCall end  ***\n");
+  } else {
+    LLVM_DEBUG(dbgs() << "[DwarfDebug] FDESubproutine skipped  ***\n");
+    // writeFDESubroutine(m_pModule);
   }
 
   ScopeVariables.clear();
@@ -3540,10 +3535,6 @@ void DwarfDebug::writeFDEStackCall(VISAModule *m) {
       Asm->EmitInt8(byte);
   }
 }
-bool DwarfDebug::DwarfFrameSectionNeeded() const {
-  return (m_pModule->hasOrIsStackCall(*VisaDbgInfo) ||
-          (!m_pModule->getSubroutines(*VisaDbgInfo)->empty()));
-}
 
 llvm::MCSymbol *DwarfDebug::GetLabelBeforeIp(unsigned int ip) {
   auto it = LabelsBeforeIp.find(ip);

IGC/DebugInfo/DwarfDebug.hpp

@@ -747,7 +747,6 @@ class DwarfDebug {
   uint32_t writeStackcallCIE();
   void writeFDESubroutine(VISAModule *m);
   void writeFDEStackCall(VISAModule *m);
-  bool DwarfFrameSectionNeeded() const;
 
   // Store offset of 2 CIEs, one for stack call and other for subroutines.
   uint32_t offsetCIEStackCall = 0;

IGC/VectorCompiler/test/DebugInfo/basic.ll

@@ -11,7 +11,7 @@
 ; RUN: -vc-dbginfo-dumps-name-override=%basename_t \
 ; RUN: -finalizer-opts='-generateDebugInfo' -o /dev/null
 
-; RUN: llvm-dwarfdump -a dbginfo_%basename_t_test_kernel_dwarf.elf | FileCheck %s
+; RUN: llvm-dwarfdump -debug-info -debug-line -debug-abbrev dbginfo_%basename_t_test_kernel_dwarf.elf | FileCheck %s
 
 ; CHECK: .debug_abbrev contents:
 ; CHECK: .debug_info contents:

IGC/VectorCompiler/test/DebugInfo/line_num.ll

@@ -10,7 +10,7 @@
 ; RUN: -vc-enable-dbginfo-dumps -vc-dbginfo-dumps-name-override=%basename_t \
 ; RUN: -finalizer-opts='-generateDebugInfo -noschedule' -o /dev/null
 
-; RUN: llvm-dwarfdump -a dbginfo_%basename_t_test_kernel_dwarf.elf | FileCheck %s
+; RUN: llvm-dwarfdump -debug-line dbginfo_%basename_t_test_kernel_dwarf.elf | FileCheck %s
 
 ; CHECK: Address Line Column File ISA Discriminator Flags
 ; CHECK:           42      0    1   0           0   is_stmt