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Simplify LTO flag passing in get_clang_flags #27407

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Merged
sbc100 merged 1 commit into from
Jul 23, 2026
Merged

Simplify LTO flag passing in get_clang_flags #27407

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17 changes: 2 additions & 15 deletions tools/compile.py
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Original file line number Diff line number Diff line change
Expand Up @@ -61,21 +61,8 @@ def get_clang_flags(user_args):
# to be exported to other DSO's by default.
flags.append('-fvisibility=default')

if settings.LTO:
if not any(a.startswith('-flto') for a in user_args):

@sbc100 sbc100 Jul 23, 2026

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I think this probably dates back to when users could do -sLTO maybe, so the setting might be enabled without -flto being on the command line.

flags.append('-flto=' + settings.LTO)
# setjmp/longjmp handling using Wasm EH
# For non-LTO, '-mllvm -wasm-enable-eh' added in
# building.llvm_backend_args() sets this feature in clang. But in LTO, the
# argument is added to wasm-ld instead, so clang needs to know that EH is
# enabled so that it can be added to the attributes in LLVM IR.
if settings.SUPPORT_LONGJMP == 'wasm':
flags.append('-mexception-handling')

else:
# In LTO mode these args get passed instead at link time when the backend runs.
for a in building.llvm_backend_args():
flags += ['-mllvm', a]
for a in building.llvm_backend_args():
flags += ['-mllvm', a]

return flags

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