Don't hoist or sink instructions with physreg uses if the physreg is
allocatable. Even if it doesn't appear to have any defs, it may latter
on after register allocation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82834 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineSink.cpp b/lib/CodeGen/MachineSink.cpp
index 5f555b2..636dad8 100644
--- a/lib/CodeGen/MachineSink.cpp
+++ b/lib/CodeGen/MachineSink.cpp
@@ -39,6 +39,7 @@
MachineFunction *CurMF; // Current MachineFunction
MachineRegisterInfo *RegInfo; // Machine register information
MachineDominatorTree *DT; // Machine dominator tree
+ BitVector AllocatableSet; // Which physregs are allocatable?
public:
static char ID; // Pass identification
@@ -99,6 +100,7 @@
TRI = TM->getRegisterInfo();
RegInfo = &CurMF->getRegInfo();
DT = &getAnalysis<MachineDominatorTree>();
+ AllocatableSet = TRI->getAllocatableSet(*CurMF);
bool EverMadeChange = false;
@@ -180,13 +182,20 @@
// we can move it, but only if the def is dead.
if (MO.isUse()) {
// If the physreg has no defs anywhere, it's just an ambient register
- // and we can freely move its uses.
+ // and we can freely move its uses. Alternatively, if it's allocatable,
+ // it could get allocated to something with a def during allocation.
if (!RegInfo->def_empty(Reg))
return false;
+ if (AllocatableSet.test(Reg))
+ return false;
// Check for a def among the register's aliases too.
- for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias)
- if (!RegInfo->def_empty(*Alias))
+ for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
+ unsigned AliasReg = *Alias;
+ if (!RegInfo->def_empty(AliasReg))
return false;
+ if (AllocatableSet.test(AliasReg))
+ return false;
+ }
} else if (!MO.isDead()) {
// A def that isn't dead. We can't move it.
return false;