Model inline asm constraint which ties an input to an output register as machine operand TIED_TO constraint. This eliminated the need to pre-allocate registers for these. This also allows register allocator can eliminate the unneeded copies.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@67512 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 29be67b..b5c2195 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -477,8 +477,8 @@
assert(interval.containsOneValue());
unsigned DefIndex = getDefIndex(interval.getValNumInfo(0)->def);
unsigned RedefIndex = getDefIndex(MIIdx);
- // It cannot be an early clobber MO.
- assert(!MO.isEarlyClobber() && "Unexpected early clobber!");
+ if (MO.isEarlyClobber())
+ RedefIndex = getUseIndex(MIIdx);
const LiveRange *OldLR = interval.getLiveRangeContaining(RedefIndex-1);
VNInfo *OldValNo = OldLR->valno;
@@ -499,6 +499,8 @@
// Value#0 is now defined by the 2-addr instruction.
OldValNo->def = RedefIndex;
OldValNo->copy = 0;
+ if (MO.isEarlyClobber())
+ OldValNo->redefByEC = true;
// Add the new live interval which replaces the range for the input copy.
LiveRange LR(DefIndex, RedefIndex, ValNo);
@@ -546,8 +548,8 @@
// live until the end of the block. We've already taken care of the
// rest of the live range.
unsigned defIndex = getDefIndex(MIIdx);
- // It cannot be an early clobber MO.
- assert(!MO.isEarlyClobber() && "Unexpected early clobber!");
+ if (MO.isEarlyClobber())
+ defIndex = getUseIndex(MIIdx);
VNInfo *ValNo;
MachineInstr *CopyMI = NULL;