enable -flto for unix systems #3407
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Different build setups require different tools for the archive step. Hence, we make the ar command a variable, so that the correct tool can be specified for each environment. Signed-off-by: Norbert Manthey <[email protected]>
Link time optimization allows inlining functions that would be located in other building blocks otherwise. This might result in better performance, but also in more compile time errors. To be able to use flto objects in archives, instead of ar the tool gcc-ar has to be used. Hence, when adding flto to CXX_FLAGS, also change AR from ar to gcc-ar. Signed-off-by: Norbert Manthey <[email protected]>
nmanthey
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chrisr-diffblue,
kroening,
peterschrammel,
smowton and
tautschnig
as code owners
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@peterschrammel: I wonder whether -flto is useful to be included for the binary that'll be submitted to SVCOMP. If you have resources for another test, that would be helpful. |
kroening
added
the
Needs data
| @@ -35,6 +35,9 @@ endif | |||
| CFLAGS ?= -Wall -O2 | |||
| CP_CFLAGS = -MMD -MP | |||
| CXXFLAGS ?= -Wall -O2 | |||
| CXXFLAGS += -flto | |||
| LINKFLAGS += -flto | |||
| AR = gcc-ar | |||
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I guess CI will probably tell us this, but will this work with clang builds?
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Is this feature supposed to be stable in g++-5 ?
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I wonder whether the bug in CI is an flto stability error, or an actual problem in the code base that's now uncovered. |
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Closing as (as discussed in #6011 ) this may not be stable/suitable. |
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These changes might improve the performance of CBMC, as well as allow to spot compilation problems earlier.