Fix MachineSink to be able to sink instructions that use physical registers
which have no defs anywhere in the function. In particular, this fixes sinking
of instructions that reference RIP on x86-64, which is currently being modeled
as a register.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82815 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineSink.cpp b/lib/CodeGen/MachineSink.cpp
index f975ad3..5f555b2 100644
--- a/lib/CodeGen/MachineSink.cpp
+++ b/lib/CodeGen/MachineSink.cpp
@@ -35,6 +35,7 @@
class VISIBILITY_HIDDEN MachineSinking : public MachineFunctionPass {
const TargetMachine *TM;
const TargetInstrInfo *TII;
+ const TargetRegisterInfo *TRI;
MachineFunction *CurMF; // Current MachineFunction
MachineRegisterInfo *RegInfo; // Machine register information
MachineDominatorTree *DT; // Machine dominator tree
@@ -95,6 +96,7 @@
CurMF = &MF;
TM = &CurMF->getTarget();
TII = TM->getInstrInfo();
+ TRI = TM->getRegisterInfo();
RegInfo = &CurMF->getRegInfo();
DT = &getAnalysis<MachineDominatorTree>();
@@ -176,8 +178,19 @@
if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
// If this is a physical register use, we can't move it. If it is a def,
// we can move it, but only if the def is dead.
- if (MO.isUse() || !MO.isDead())
+ if (MO.isUse()) {
+ // If the physreg has no defs anywhere, it's just an ambient register
+ // and we can freely move its uses.
+ if (!RegInfo->def_empty(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))
+ return false;
+ } else if (!MO.isDead()) {
+ // A def that isn't dead. We can't move it.
return false;
+ }
} else {
// Virtual register uses are always safe to sink.
if (MO.isUse()) continue;