[LiveDebugVariables] Strip all debug instructions from nodebug functions

A crash/assertion failure in the greedy register allocator was tracked
down to a debug instr being passed to LiveIntervals::getInstructionIndex.
Normally this should not occur as debug instructions are collected and
removed by LiveDebugVariables before RA, and reinserted afterwards.
However, when a function has no debug info, LiveDebugVariables simply
strips any debug values that are present as they're not needed (this
situation will occur when a function with debug info is inlined into a
nodebug function). The problem is, it only removes DBG_VALUE instructions,
leaving DBG_LABELs (the cause of the crash).

This patch updates the LiveDebugVariables nodebug path to remove all debug
instructions. The test case verifies that DBG_VALUE/DBG_LABEL instructions
are present, and that they are stripped.

When -experimental-debug-variable-locations is enabled, certain variable
locations are represented by DBG_INSTR_REF instead of DBG_VALUE. The test
case verifies that a DBG_INSTR_REF is emitted by the option, and that it
is also stripped.

Differential Revision: https://reviews.llvm.org/D92127

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/LiveDebugVariables.cpp b/llvm/lib/CodeGen/LiveDebugVariables.cpp
index f4238bd..2325341 100644
--- a/llvm/lib/CodeGen/LiveDebugVariables.cpp
+++ b/llvm/lib/CodeGen/LiveDebugVariables.cpp
@@ -1022,10 +1022,10 @@ bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
   return Changed;
 }
 
-static void removeDebugValues(MachineFunction &mf) {
+static void removeDebugInstrs(MachineFunction &mf) {
   for (MachineBasicBlock &MBB : mf) {
     for (auto MBBI = MBB.begin(), MBBE = MBB.end(); MBBI != MBBE; ) {
-      if (!MBBI->isDebugValue()) {
+      if (!MBBI->isDebugInstr()) {
         ++MBBI;
         continue;
       }
@@ -1038,7 +1038,7 @@ bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) {
   if (!EnableLDV)
     return false;
   if (!mf.getFunction().getSubprogram()) {
-    removeDebugValues(mf);
+    removeDebugInstrs(mf);
     return false;
   }
   if (!pImpl)