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b96943b6a0
Summary: When calculating the debug value history, DbgEntityHistoryCalculator would only keep track of register clobbering for the latest debug value per inlined entity. This meant that preceding register-described debug value fragments would live on until the next overlapping debug value, ignoring any potential clobbering. This patch amends DbgEntityHistoryCalculator so that it keeps track of all registers that a inlined entity's currently live debug values are described by. The DebugInfo/COFF/pieces.ll test case has had to be changed since previously a register-described fragment would incorrectly outlive its basic block. The parent patch D59941 is expected to increase the coverage slightly, as it makes sure that location list entries are inserted after clobbered fragments, and this patch is expected to decrease it, as it stops preceding register-described from living longer than they should. All in all, this patch and the preceding patch has a negligible effect on the output from `llvm-dwarfdump -statistics' for a clang-3.4 binary built using the RelWithDebInfo build profile. "Scope bytes covered" increases by 0.5%, and "variables with location" increases from 2212083 to 2212088, but it should improve the accuracy quite a bit. This fixes PR40283. Reviewers: aprantl, probinson, dblaikie, rnk, bjope Reviewed By: aprantl Subscribers: llvm-commits Tags: #debug-info, #llvm Differential Revision: https://reviews.llvm.org/D59942 llvm-svn: 358073