gh-101525: configure: Add PIE detection logic for BOLT optimizations compatibility #140203
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BOLT requires the --relocs flag if a binary is built as PIE (Position Independent Executable). Test if a build system enforces PIE during compilation, via the preprocessor macros, or via linkage via creating a test binary. If so, -fno-pie and -no-pie flags will not be enforced when --enable-bolt is used and --relocs will be added to the BOLT flags.
stratakis
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AA-Turner,
corona10,
emmatyping and
erlend-aasland
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BOLT requires the --relocs flag if a binary is built as PIE (Position Independent Executable).
Test if a build system enforces PIE during compilation, via the preprocessor macros, or via linkage via creating a test binary.
If so, -fno-pie and -no-pie flags will not be enforced when --enable-bolt is used and --relocs will be added to the BOLT flags.
This resolves the compilation failure when enabling BOLT optimizations in Fedora, where -pie is enforced during linkage and also hidden inside GCC specs.
Tested with both llvm and gcc, static and shared builds, lto combinations and -fPIE,-pie in CFLAGS, LDFLAGS.
Note: This change adds a dependency on
filefor unix when using --enable-bolt. I'm not aware of a better way to test for -pie in the linker flags when it's hidden behind GCC specs, unless I grep for the Fedora specific GCC specs, essentially the-specs=/usr/lib/rpm/redhat/redhat-hardened-ldlinker flag.fileis used in configure here for MacOS builds.