[BranchFolding] do not iterate the aliases of virtual registers
Summary:
MCRegAliasIterator only works for physical registers. So, do not run it
on virtual registers.
With this issue fixed, we can resurrect the BranchFolding pass in NVPTX
backend.
Reviewers: jholewinski, bkramer
Subscribers: henryhu, meheff, llvm-commits, jholewinski
Differential Revision: http://reviews.llvm.org/D11174
llvm-svn: 242871
diff --git a/llvm/lib/CodeGen/BranchFolding.cpp b/llvm/lib/CodeGen/BranchFolding.cpp
index 6182667..608f021 100644
--- a/llvm/lib/CodeGen/BranchFolding.cpp
+++ b/llvm/lib/CodeGen/BranchFolding.cpp
@@ -12,7 +12,8 @@
// it then removes.
//
// Note that this pass must be run after register allocation, it cannot handle
-// SSA form.
+// SSA form. It also must handle virtual registers for targets that emit virtual
+// ISA (e.g. NVPTX).
//
//===----------------------------------------------------------------------===//
@@ -1573,6 +1574,17 @@
return nullptr;
}
+template <class Container>
+static void addRegAndItsAliases(unsigned Reg, const TargetRegisterInfo *TRI,
+ Container &Set) {
+ if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
+ for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
+ Set.insert(*AI);
+ } else {
+ Set.insert(Reg);
+ }
+}
+
/// findHoistingInsertPosAndDeps - Find the location to move common instructions
/// in successors to. The location is usually just before the terminator,
/// however if the terminator is a conditional branch and its previous
@@ -1598,8 +1610,7 @@
if (!Reg)
continue;
if (MO.isUse()) {
- for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
- Uses.insert(*AI);
+ addRegAndItsAliases(Reg, TRI, Uses);
} else {
if (!MO.isDead())
// Don't try to hoist code in the rare case the terminator defines a
@@ -1608,8 +1619,7 @@
// If the terminator defines a register, make sure we don't hoist
// the instruction whose def might be clobbered by the terminator.
- for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
- Defs.insert(*AI);
+ addRegAndItsAliases(Reg, TRI, Defs);
}
}
@@ -1665,15 +1675,15 @@
if (!Reg)
continue;
if (MO.isUse()) {
- for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
- Uses.insert(*AI);
+ addRegAndItsAliases(Reg, TRI, Uses);
} else {
if (Uses.erase(Reg)) {
- for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs)
- Uses.erase(*SubRegs); // Use sub-registers to be conservative
+ if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
+ for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs)
+ Uses.erase(*SubRegs); // Use sub-registers to be conservative
+ }
}
- for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
- Defs.insert(*AI);
+ addRegAndItsAliases(Reg, TRI, Defs);
}
}
@@ -1800,8 +1810,12 @@
unsigned Reg = MO.getReg();
if (!Reg || !LocalDefsSet.count(Reg))
continue;
- for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
- LocalDefsSet.erase(*AI);
+ if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
+ for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
+ LocalDefsSet.erase(*AI);
+ } else {
+ LocalDefsSet.erase(Reg);
+ }
}
// Track local defs so we can update liveins.
@@ -1813,8 +1827,7 @@
if (!Reg)
continue;
LocalDefs.push_back(Reg);
- for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
- LocalDefsSet.insert(*AI);
+ addRegAndItsAliases(Reg, TRI, LocalDefsSet);
}
HasDups = true;