[PATCH] D128501: [CodeGen] Make uninitialized Lvalue bit-field stores poison compatible

[John McIver via Phabricator via cfe-commits]

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Poison compatibility is provided by emitting a freeze instruction, post load,
for all Lvalue bit-field store operations. This solution is indiscriminate to
the initialization state and thus the freeze instruction may hide poison during
subsequent re-assignments.

This patch implements the first proposed solution from the following RFC:
https://discourse.llvm.org/t/rfc-making-bit-field-codegen-poison-compatible/63250

The test-suite is passing; my current setup is not idea for timing information.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D128501

Files:
  clang/lib/CodeGen/CGExpr.cpp
  clang/test/CodeGen/aapcs-bitfield.c
  clang/test/CodeGen/no-bitfield-type-align.c
  clang/test/CodeGenCXX/alignment.cpp
  clang/test/CodeGenCXX/bitfield.cpp
  clang/test/CodeGenCXX/ext-int.cpp
  clang/test/CodeGenCXX/finegrain-bitfield-access.cpp
  clang/test/CodeGenCXX/ignored-bitfield-conditional.cpp
  clang/test/CodeGenCXX/references.cpp
  clang/test/CodeGenObjC/strong-in-c-struct.m
  clang/test/OpenMP/atomic_capture_codegen.cpp
  clang/test/OpenMP/atomic_update_codegen.cpp
  clang/test/OpenMP/atomic_write_codegen.c
  clang/test/OpenMP/for_lastprivate_codegen.cpp
  clang/test/OpenMP/for_linear_codegen.cpp
  clang/test/OpenMP/parallel_firstprivate_codegen.cpp
  clang/test/OpenMP/parallel_private_codegen.cpp
  clang/test/OpenMP/parallel_reduction_codegen.cpp
  clang/test/OpenMP/single_codegen.cpp
  clang/test/OpenMP/teams_private_codegen.cpp

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