[llvm-bugs] [Bug 25788] New: IR parsing of floating-point constants is locale-dependent
llvm-bugs at lists.llvm.org
Wed Dec 9 04:35:47 PST 2015
Bug ID: 25788
Summary: IR parsing of floating-point constants is
Component: LLVM assembly language parser
Assignee: unassignedbugs at nondot.org
Reporter: pitrou at free.fr
CC: llvm-bugs at lists.llvm.org
Parsing of floating-point constants in decimal notation is locale-dependent.
With a locale other than C, a bogus value may be emitted. This was observed
with LLVM 3.6 but inspection of trunk suggests the issue hasn't been corrected,
as it seems due to the use of std::atof() in lib/AsmParser/LLLexer.cpp.
Not only atof() is locale-dependent, but it's quite lenient. So if for instance
you pass it "1.23e+01" and the current locale has the comma (",") as decimal
separator, atof() simply ignores the invalid trailing characters and returns
I have a small reproducer using the llvmlite bindings below (I don't seem to be
able to reproduce using the LLVM command-line tools, perhaps because they force
the locale to "C"). It parses the IR and prints out the IR of the parsed
import llvmlite.binding as llvm
ir = """
define double @func()
ret double 1.23e+01
locale.setlocale(locale.LC_ALL, ("fr_FR", "UTF-8"))
mod = llvm.parse_assembly(ir)
print(mod) # => the printed assembly returns 1.0, not 12.3...
Probably a similar reproducer can be written using the C++ API.
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