[DebugInstrRef] Parse debug instruction-references from/to MIR

This patch defines the MIR format for debug instruction references: it's an
integer trailing an instruction, marked out by "debug-instr-number", much
like how "debug-location" identifies the DebugLoc metadata of an
instruction. The instruction number is stored directly in a MachineInstr.

Actually referring to an instruction comes in a later patch, but is done
using one of these instruction numbers.

I've added a round-trip test and two verifier checks: that we don't label
meta-instructions as generating values, and that there are no duplicates.

Differential Revision: https://reviews.llvm.org/D85746

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/MachineFunction.cpp b/llvm/lib/CodeGen/MachineFunction.cpp
index 56c13096..f9fc775 100644
--- a/llvm/lib/CodeGen/MachineFunction.cpp
+++ b/llvm/lib/CodeGen/MachineFunction.cpp
@@ -943,6 +943,10 @@ void MachineFunction::moveCallSiteInfo(const MachineInstr *Old,
   CallSitesInfo[New] = CSInfo;
 }
 
+void MachineFunction::setDebugInstrNumberingCount(unsigned Num) {
+  DebugInstrNumberingCount = Num;
+}
+
 /// \}
 
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