[codeview] Bail on a DBG_VALUE register operand with no register
This apparently comes up when the register allocator decides that a
variable will become undef along a certain path.
Also improve the error message we emit when we can't map from LLVM
register number to CV register number.
llvm-svn: 261016
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index 5cbc859..9749d1c 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -594,11 +594,13 @@
if (DIExpr && DIExpr->getNumElements() > 0)
continue;
- // Bail if the value is not indirect in memory or in a register. In these
- // cases, operand 0 will not be a register.
- // FIXME: CodeView does not have an obvious representation for a variable
- // that has been optimized to be a constant.
- if (!DVInst->getOperand(0).isReg())
+ // Bail if operand 0 is not a valid register. This means the variable is a
+ // simple constant, or is described by a complex expression.
+ // FIXME: Find a way to represent constant variables, since they are
+ // relatively common.
+ unsigned Reg =
+ DVInst->getOperand(0).isReg() ? DVInst->getOperand(0).getReg() : 0;
+ if (Reg == 0)
continue;
// Handle the two cases we can handle: indirect in memory and in register.