c1cfa1757c
When emitting TBAA information for enums in C code we currently just treat the data as an 'omnipotent char'. However, with C strict aliasing this means we fail to optimise certain cases. For example, in the SPEC2017 xz benchmark there are structs that contain arrays of enums, and clang pessmistically assumes that accesses to those enums could alias with other struct members that have a different type. According to https://en.cppreference.com/w/c/language/enum enums should be treated as 'int' types unless explicitly specified (C23) or if 'int' would not be large enough to hold all the enumerated values. In the latter case the compiler is free to choose a suitable integer that would hold all such values. When compiling C code this patch generates TBAA information for the enum by using an equivalent integer of the size clang has already chosen for the enum. I have ignored C++ for now because the rules are more complex. New test added here: clang/test/CodeGen/tbaa.c |
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| .ci | ||
| .github | ||
| bolt | ||
| clang | ||
| clang-tools-extra | ||
| cmake | ||
| compiler-rt | ||
| cross-project-tests | ||
| flang | ||
| libc | ||
| libclc | ||
| libcxx | ||
| libcxxabi | ||
| libunwind | ||
| lld | ||
| lldb | ||
| llvm | ||
| llvm-libgcc | ||
| mlir | ||
| openmp | ||
| polly | ||
| pstl | ||
| runtimes | ||
| third-party | ||
| utils | ||
| .arcconfig | ||
| .arclint | ||
| .clang-format | ||
| .clang-tidy | ||
| .git-blame-ignore-revs | ||
| .gitignore | ||
| .mailmap | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| LICENSE.TXT | ||
| README.md | ||
| SECURITY.md | ||
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