[CodeGenPrepare] Reset the debug location when promoting trunc(s)

The promotion machinery in CGP moves instructions retaining
debug locations. When the transformation is local, this is mostly
correct, but when instructions are moved cross-BBs, this is not
always true and causes jumpiness in line tables. This is the first
of a series of commits. sext(s) and zext(s) need to be treated
similarly.

Differential Revision:  https://reviews.llvm.org/D81879

1 files changed, 1 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index d238804..935fc95 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -2605,6 +2605,7 @@ class TypePromotionTransaction {
     /// trunc Opnd to Ty.
     TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) {
       IRBuilder<> Builder(Opnd);
+      Builder.SetCurrentDebugLocation(DebugLoc());
       Val = Builder.CreateTrunc(Opnd, Ty, "promoted");
       LLVM_DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n");
     }