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Use -mno-implicit-float by default for kernel/kext code. <rdar://13177960> 

Apple's kernel engineers have been expecting this behavior even though
we've never implemented it before, as far as I can tell. In recent months,
clang has gotten better at using vector instructions to optimize memcpy-like
operations, and that has exposed problems when vector/floating-point
instructions are used in kexts that don't support that. This behavior also
matches what Apple's GCC did for PowerPC targets.

llvm-svn: 174838
This commit is contained in:
Bob Wilson 2013-02-10 16:01:41 +00:00
parent dc9e6085c4
commit 2616e2ec85
2 changed files with 18 additions and 4 deletions
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16
clang/lib/Driver/Tools.cpp
View File

@ -1200,10 +1200,18 @@ void Clang::AddX86TargetArgs(const ArgList &Args,
Args.hasArg(options::OPT_fapple_kext))
CmdArgs.push_back("-disable-red-zone");
if (Args.hasFlag(options::OPT_msoft_float,
options::OPT_mno_soft_float,
false) ||
Args.hasArg(options::OPT_mno_implicit_float))
// Default to avoid implicit floating-point for kernel/kext code, but allow
// that to be overridden with -mno-soft-float.
bool NoImplicitFloat = (Args.hasArg(options::OPT_mkernel) ||
Args.hasArg(options::OPT_fapple_kext));
if (Arg *A = Args.getLastArg(options::OPT_msoft_float,
options::OPT_mno_soft_float,
options::OPT_mno_implicit_float)) {
const Option &O = A->getOption();
NoImplicitFloat = (O.matches(options::OPT_mno_implicit_float) ||
O.matches(options::OPT_msoft_float));
}
if (NoImplicitFloat)
CmdArgs.push_back("-no-implicit-float");
if (const char *CPUName = getX86TargetCPU(Args, getToolChain().getTriple())) {

6
clang/test/Driver/flags.c
View File

@ -10,5 +10,11 @@
// RUN: %clang -target i386-apple-darwin9 -### -S -mno-implicit-float %s 2> %t.log
// RUN: grep '"-no-implicit-float"' %t.log
// RUN: %clang -target i386-apple-darwin9 -### -S -mkernel %s 2> %t.log
// RUN: grep '"-no-implicit-float"' %t.log
// RUN: %clang -target i386-apple-darwin9 -### -S -mkernel -mno-soft-float %s 2> %t.log
// RUN: grep '"-no-implicit-float"' %t.log | count 0
// RUN: %clang -target armv7-apple-darwin10 -### -S -mno-implicit-float %s 2> %t.log
// RUN: grep '"-no-implicit-float"' %t.log