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[CodeGen, TargetPassConfig] Remove a race from createRegAllocPass 

The createRegAllocPass reads and writes to a global variable 'Registry'
via calls to getDefault and setDefault.  Run this under a call_once to
avoid races.

llvm-svn: 274875
This commit is contained in:
David Majnemer 2016-07-08 16:39:00 +00:00
parent 44540a3db2
commit d9d02d8259
1 changed files with 14 additions and 6 deletions
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20
llvm/lib/CodeGen/TargetPassConfig.cpp
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@ -721,6 +721,7 @@ MachinePassRegistry RegisterRegAlloc::Registry;
/// A dummy default pass factory indicates whether the register allocator is
/// overridden on the command line.
LLVM_DEFINE_ONCE_FLAG(InitializeDefaultRegisterAllocatorFlag);
static FunctionPass *useDefaultRegisterAllocator() { return nullptr; }
static RegisterRegAlloc
defaultRegAlloc("default",
@ -734,6 +735,15 @@ RegAlloc("regalloc",
cl::init(&useDefaultRegisterAllocator),
cl::desc("Register allocator to use"));
static void initializeDefaultRegisterAllocatorOnce() {
RegisterRegAlloc::FunctionPassCtor Ctor = RegisterRegAlloc::getDefault();
if (!Ctor) {
Ctor = RegAlloc;
RegisterRegAlloc::setDefault(RegAlloc);
}
}
/// Instantiate the default register allocator pass for this target for either
/// the optimized or unoptimized allocation path. This will be added to the pass
@ -760,13 +770,11 @@ FunctionPass *TargetPassConfig::createTargetRegisterAllocator(bool Optimized) {
/// FIXME: When MachinePassRegistry register pass IDs instead of function ptrs,
/// this can be folded into addPass.
FunctionPass *TargetPassConfig::createRegAllocPass(bool Optimized) {
RegisterRegAlloc::FunctionPassCtor Ctor = RegisterRegAlloc::getDefault();
// Initialize the global default.
if (!Ctor) {
Ctor = RegAlloc;
RegisterRegAlloc::setDefault(RegAlloc);
}
llvm::call_once(InitializeDefaultRegisterAllocatorFlag,
initializeDefaultRegisterAllocatorOnce);
RegisterRegAlloc::FunctionPassCtor Ctor = RegisterRegAlloc::getDefault();
if (Ctor != useDefaultRegisterAllocator)
return Ctor();