[llvm] [llvm][DebugInfo] Emit 0/1 for constant boolean values (PR #151225)

[Jeremy Morse via llvm-commits]

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@@ -733,6 +733,8 @@ MachineOperand GetMOForConstDbgOp(const SDDbgOperand &Op) {
   if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
     if (CI->getBitWidth() > 64)
       return MachineOperand::CreateCImm(CI);
+    if (CI->getBitWidth() == 1)
+      return MachineOperand::CreateImm(CI->getZExtValue());
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jmorse wrote:

IMO isel is the right place to put this today (ideally in a year this would all be place in a non-instruction format). It can't be earlier because LLVM-IR transforms will continue to mutate the type of operands to dbg.values. If it's later than isel, it'd need to be in three places (LiveDebugValues, location-list builder, DWARF emitter) so that identical-booleans can be recognised as such and have location-ranges merged (or at least, not conflict and become "optimised out"), which is what we risk with a de-normalised boolean-true. Plus: isel is the natural place to normalise when we reach a non-instruction debug-info format in MIR.

Again, I'm not saying breaking convention here isn't a bad thing, IMO it's the least worst of several normalisation options.

https://github.com/llvm/llvm-project/pull/151225