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Pass -gcodeview-ghash when using clang-cl and lld-link 

This precomputes some hashes that LLD uses for type merging to speed up
linking when PDBs are enabled. Only do this if any kind of /DEBUG flag
is passed to the linker. -gcodeview-ghash is orthogonal to /Z7, -g, -g1,
or -gmlt, so it is safe to set it independently from those flags. It
will not increase debug info emission.

Differential Revision: https://reviews.llvm.org/D103287
This commit is contained in:
Reid Kleckner 2021-05-27 14:32:48 -07:00
parent 59b8afe502
commit ef4cfd8322
1 changed files with 18 additions and 7 deletions
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25
llvm/cmake/modules/HandleLLVMOptions.cmake
View File

@ -474,6 +474,23 @@ if( MSVC )
CMAKE_SHARED_LINKER_FLAGS)
endif()
# Get all linker flags in upper case form so we can search them.
set(all_linker_flags_uppercase
"${CMAKE_EXE_LINKER_FLAGS} ${CMAKE_MODULE_LINKER_FLAGS} ${CMAKE_SHARED_LINKER_FLAGS}")
string(TOUPPER "${all_linker_flags_uppercase}" all_linker_flags_uppercase)
if (CLANG_CL AND LINKER_IS_LLD)
# If we are using clang-cl with lld-link and /debug is present in any of the
# linker flag variables, pass -gcodeview-ghash to the compiler to speed up
# linking. This flag is orthogonal from /Zi, /Z7, and other flags that
# enable debug info emission, and only has an effect if those are also in
# use.
string(FIND "${all_linker_flags_uppercase}" "/DEBUG" linker_flag_idx)
if (${linker_flag_idx} GREATER -1)
add_flag_if_supported("-gcodeview-ghash" GCODEVIEW_GHASH)
endif()
endif()
# Disable string literal const->non-const type conversion.
# "When specified, the compiler requires strict const-qualification
# conformance for pointers initialized by using string literals."
@ -499,13 +516,7 @@ if( MSVC )
if (SUPPORTS_BREPRO)
# Check if /INCREMENTAL is passed to the linker and complain that it
# won't work with /Brepro.
string(TOUPPER "${CMAKE_EXE_LINKER_FLAGS}" upper_exe_flags)
string(TOUPPER "${CMAKE_MODULE_LINKER_FLAGS}" upper_module_flags)
string(TOUPPER "${CMAKE_SHARED_LINKER_FLAGS}" upper_shared_flags)
string(FIND "${upper_exe_flags} ${upper_module_flags} ${upper_shared_flags}"
"/INCREMENTAL" linker_flag_idx)
string(FIND "${all_linker_flags_uppercase}" "/INCREMENTAL" linker_flag_idx)
if (${linker_flag_idx} GREATER -1)
message(WARNING "/Brepro not compatible with /INCREMENTAL linking - builds will be non-deterministic")
else()