Consider the livein/out set for a function, allowing targets to not have to
use ugly imp_def/imp_uses for arguments and return values.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21180 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp
index 8031610..175b5fd 100644
--- a/lib/CodeGen/LiveVariables.cpp
+++ b/lib/CodeGen/LiveVariables.cpp
@@ -163,6 +163,14 @@
/// Get some space for a respectable number of registers...
VirtRegInfo.resize(64);
+
+ // Mark live-in registers as live-in.
+ for (MachineFunction::liveinout_iterator I = MF.livein_begin(),
+ E = MF.livein_end(); I != E; ++I) {
+ assert(MRegisterInfo::isPhysicalRegister(*I) &&
+ "Cannot have a live-in virtual register!");
+ HandlePhysRegDef(*I, 0);
+ }
// Calculate live variable information in depth first order on the CFG of the
// function. This guarantees that we will see the definition of a virtual
@@ -260,6 +268,18 @@
}
}
+ // Finally, if the last block in the function is a return, make sure to mark
+ // it as using all of the live-out values in the function.
+ if (!MBB->empty() && TII.isReturn(MBB->back().getOpcode())) {
+ MachineInstr *Ret = &MBB->back();
+ for (MachineFunction::liveinout_iterator I = MF.liveout_begin(),
+ E = MF.liveout_end(); I != E; ++I) {
+ assert(MRegisterInfo::isPhysicalRegister(*I) &&
+ "Cannot have a live-in virtual register!");
+ HandlePhysRegUse(*I, Ret);
+ }
+ }
+
// Loop over PhysRegInfo, killing any registers that are available at the
// end of the basic block. This also resets the PhysRegInfo map.
for (unsigned i = 0, e = RegInfo->getNumRegs(); i != e; ++i)