Changes in directory llvm/lib/CodeGen:
VirtRegMap.cpp updated: 1.94 -> 1.95
---
Log message:
Fixed a long standing spiller bug that's exposed by Thumb:
The code sequence before the spiller is something like:
= tMOVrr
%reg1117 = tMOVrr
%reg1078 = tLSLri %reg1117, 2
The it starts spilling:
%r0 = tRestore <fi#5>, 0
%r1 = tRestore <fi#7>, 0
%r1 = tMOVrr %r1<kill>
tSpill %r1, <fi#5>, 0
%reg1078 = tLSLri %reg1117, 2
It restores the value while processing the first tMOVrr. At this point, the
spiller remembers fi#5 is available in %r0. Next it processes the second move.
It restores the source before the move and spills the result afterwards. The
move becomes a noop and is deleted. However, a spill has been inserted and that
should invalidate reuse of %r0 for fi#5 and add reuse of %r1 for fi#5.
Therefore, %reg1117 (which is also assigned fi#5) should get %r1, not %r0.
---
Diffs of the changes: (+13 -13)
VirtRegMap.cpp | 26 +++++++++++++-------------
1 files changed, 13 insertions(+), 13 deletions(-)
Index: llvm/lib/CodeGen/VirtRegMap.cpp
diff -u llvm/lib/CodeGen/VirtRegMap.cpp:1.94
llvm/lib/CodeGen/VirtRegMap.cpp:1.95
--- llvm/lib/CodeGen/VirtRegMap.cpp:1.94 Mon Jan 22 18:59:48 2007
+++ llvm/lib/CodeGen/VirtRegMap.cpp Thu Feb 8 00:04:54 2007
@@ -923,19 +923,6 @@
DOUT << "Store:\t" << *next(MII);
MI.getOperand(i).setReg(PhysReg);
- // Check to see if this is a noop copy. If so, eliminate the
- // instruction before considering the dest reg to be changed.
- {
- unsigned Src, Dst;
- if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
- ++NumDCE;
- DOUT << "Removing now-noop copy: " << MI;
- MBB.erase(&MI);
- VRM.RemoveFromFoldedVirtMap(&MI);
- goto ProcessNextInst;
- }
- }
-
// If there is a dead store to this stack slot, nuke it now.
MachineInstr *&LastStore = MaybeDeadStores[StackSlot];
if (LastStore) {
@@ -953,6 +940,19 @@
Spills.ClobberPhysReg(PhysReg);
Spills.addAvailable(StackSlot, PhysReg);
++NumStores;
+
+ // Check to see if this is a noop copy. If so, eliminate the
+ // instruction before considering the dest reg to be changed.
+ {
+ unsigned Src, Dst;
+ if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
+ ++NumDCE;
+ DOUT << "Removing now-noop copy: " << MI;
+ MBB.erase(&MI);
+ VRM.RemoveFromFoldedVirtMap(&MI);
+ goto ProcessNextInst;
+ }
+ }
}
}
ProcessNextInst:
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