Teach isSafeToClobberEFLAGS to ignore dbg_value's. We need a MachineBasicBlock::iterator that does this automatically?
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99320 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp
index 139a905..2323f57 100644
--- a/lib/Target/X86/X86InstrInfo.cpp
+++ b/lib/Target/X86/X86InstrInfo.cpp
@@ -992,8 +992,10 @@
/// a few instructions in each direction it assumes it's not safe.
static bool isSafeToClobberEFLAGS(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) {
+ MachineBasicBlock::iterator E = MBB.end();
+
// It's always safe to clobber EFLAGS at the end of a block.
- if (I == MBB.end())
+ if (I == E)
return true;
// For compile time consideration, if we are not able to determine the
@@ -1017,20 +1019,28 @@
// This instruction defines EFLAGS, no need to look any further.
return true;
++Iter;
+ // Skip over DBG_VALUE.
+ while (Iter != E && Iter->isDebugValue())
+ ++Iter;
// If we make it to the end of the block, it's safe to clobber EFLAGS.
- if (Iter == MBB.end())
+ if (Iter == E)
return true;
}
+ MachineBasicBlock::iterator B = MBB.begin();
Iter = I;
for (unsigned i = 0; i < 4; ++i) {
// If we make it to the beginning of the block, it's safe to clobber
// EFLAGS iff EFLAGS is not live-in.
- if (Iter == MBB.begin())
+ if (Iter == B)
return !MBB.isLiveIn(X86::EFLAGS);
--Iter;
+ // Skip over DBG_VALUE.
+ while (Iter != B && Iter->isDebugValue())
+ --Iter;
+
bool SawKill = false;
for (unsigned j = 0, e = Iter->getNumOperands(); j != e; ++j) {
MachineOperand &MO = Iter->getOperand(j);