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[SimplifyLibCalls] Ignore nobuiltin/unavailable fortified libcalls.

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We used to do this before refactorings around r225640.
Some clang users checked for _chk libcall availability using:
  __has_builtin(__builtin___memcpy_chk)
When compiling with -fno-builtin, this is always true.
When passing -ffreestanding/-mkernel, which both imply -fno-builtin, we
end up with fortified libcalls, which isn't acceptable in a freestanding
environment which only provides their non-fortified counterparts.

Until we change clang and/or teach external users to check for availability
differently, disregard the "nobuiltin" attribute and TLI::has.

Workaround for PR23093.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233776 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Ahmed Bougacha
2015-04-01 00:45:09 +00:00
parent 54ab6ce385
commit 252c120f4a
2 changed files with 31 additions and 3 deletions
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16
lib/Transforms/Utils/SimplifyLibCalls.cpp
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@@ -2322,8 +2322,18 @@ Value *FortifiedLibCallSimplifier::optimizeStrpNCpyChk(CallInst *CI,
}
Value *FortifiedLibCallSimplifier::optimizeCall(CallInst *CI) {
if (CI->isNoBuiltin())
return nullptr;
// FIXME: We shouldn't be changing "nobuiltin" or TLI unavailable calls here.
// Some clang users checked for _chk libcall availability using:
// __has_builtin(__builtin___memcpy_chk)
// When compiling with -fno-builtin, this is always true.
// When passing -ffreestanding/-mkernel, which both imply -fno-builtin, we
// end up with fortified libcalls, which isn't acceptable in a freestanding
// environment which only provides their non-fortified counterparts.
//
// Until we change clang and/or teach external users to check for availability
// differently, disregard the "nobuiltin" attribute and TLI::has.
//
// PR23093.
LibFunc::Func Func;
Function *Callee = CI->getCalledFunction();
@@ -2332,7 +2342,7 @@ Value *FortifiedLibCallSimplifier::optimizeCall(CallInst *CI) {
bool isCallingConvC = CI->getCallingConv() == llvm::CallingConv::C;
// First, check that this is a known library functions.
if (!TLI->getLibFunc(FuncName, Func) || !TLI->has(Func))
if (!TLI->getLibFunc(FuncName, Func))
return nullptr;
// We never change the calling convention.