[ShrinkWrap] Add a target hook to check whether or not
the target can handle a given basic block as prologue
or epilogue.
Related to <rdar://problem/20821487>
llvm-svn: 238292
diff --git a/llvm/lib/CodeGen/ShrinkWrap.cpp b/llvm/lib/CodeGen/ShrinkWrap.cpp
index e1869b3..4463cc7 100644
--- a/llvm/lib/CodeGen/ShrinkWrap.cpp
+++ b/llvm/lib/CodeGen/ShrinkWrap.cpp
@@ -62,6 +62,8 @@
// To know about callee-saved.
#include "llvm/CodeGen/RegisterClassInfo.h"
#include "llvm/Support/Debug.h"
+// To query the target about frame lowering.
+#include "llvm/Target/TargetFrameLowering.h"
// To know about frame setup operation.
#include "llvm/Target/TargetInstrInfo.h"
// To access TargetInstrInfo.
@@ -338,6 +340,7 @@
DEBUG(dbgs() << "\n ** Results **\nFrequency of the Entry: " << EntryFreq
<< '\n');
+ const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
do {
DEBUG(dbgs() << "Shrink wrap candidates (#, Name, Freq):\nSave: "
<< Save->getNumber() << ' ' << Save->getName() << ' '
@@ -345,13 +348,15 @@
<< Restore->getNumber() << ' ' << Restore->getName() << ' '
<< MBFI->getBlockFreq(Restore).getFrequency() << '\n');
- bool IsSaveCheap;
- if ((IsSaveCheap = EntryFreq >= MBFI->getBlockFreq(Save).getFrequency()) &&
- EntryFreq >= MBFI->getBlockFreq(Restore).getFrequency())
+ bool IsSaveCheap, TargetCanUseSaveAsPrologue = false;
+ if (((IsSaveCheap = EntryFreq >= MBFI->getBlockFreq(Save).getFrequency()) &&
+ EntryFreq >= MBFI->getBlockFreq(Restore).getFrequency()) &&
+ ((TargetCanUseSaveAsPrologue = TFI->canUseAsPrologue(*Save)) &&
+ TFI->canUseAsEpilogue(*Restore)))
break;
- DEBUG(dbgs() << "New points are too expensive\n");
+ DEBUG(dbgs() << "New points are too expensive or invalid for the target\n");
MachineBasicBlock *NewBB;
- if (!IsSaveCheap) {
+ if (!IsSaveCheap || !TargetCanUseSaveAsPrologue) {
Save = FindIDom<>(*Save, Save->predecessors(), *MDT);
if (!Save)
break;