[PATCH] D27163: Introduce -f[no-]strict-return flag that controls code generation for C++'s undefined behaviour return optimisation

[Alex Lorenz via Phabricator via cfe-commits]

arphaman created this revision.
arphaman added reviewers: rjmccall, rsmith, mehdi_amini.
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This patch adds a new clang flag called `-f[no-]strict-return`. The purpose of this flag is to control how the code generator applies the undefined behaviour return optimisation to value returning functions that flow-off without a required return:

- If -fstrict-return is on (default for non Darwin targets), then the code generator follows the current behaviour: it emits the IR for the undefined behaviour (trap with unreachable).

- Otherwise, the code generator emits the IR for the undefined behaviour only if the function avoided -Wreturn-type warnings. This avoidance is detected even if -Wreturn-type warnings are disabled (-Wno-return-type).




Repository:
  rL LLVM

https://reviews.llvm.org/D27163

Files:
  include/clang/AST/Decl.h
  include/clang/Basic/LangOptions.def
  include/clang/Driver/Options.td
  include/clang/Frontend/CodeGenOptions.def
  include/clang/Sema/AnalysisBasedWarnings.h
  include/clang/Sema/Sema.h
  lib/CodeGen/CodeGenFunction.cpp
  lib/Driver/Tools.cpp
  lib/Frontend/CompilerInvocation.cpp
  lib/Sema/AnalysisBasedWarnings.cpp
  lib/Sema/Sema.cpp
  test/CodeGenCXX/return.cpp
  test/Driver/clang_f_opts.c
  test/Driver/darwin-no-strict-return.c

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