When the Constant Hoisting pass moves expensive constants into a
common block, it would assign a debug location equal to the last use
of that constant. While this is certainly intuitive, it places the
constant in an out-of-order location, according to the debug location
information. This produces out-of-order stepping when debugging
programs affected by this pass.
This patch creates in-order stepping behavior by merging the debug
locations for hoisted constants, and the new insertion point.
Patch by Matthew Voss!
Differential Revision: https://reviews.llvm.org/D38088
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@317827 91177308-0d34-0410-b5e6-96231b3b80d8
4c7c4551f2