6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-03-06 05:33:28 +00:00
Code Issues Projects Releases Wiki Activity

Fix a bug in the local spiller, where we could take code like this:

Browse Source 
store r12 -> [ss#2]
  R3 = load [ss#1]
  use R3
  R3 = load [ss#2]
  R4 = load [ss#1]

and turn it into this code:

  store R12 -> [ss#2]
  R3 = load [ss#1]
  use R3
  R3 = R12
  R4 = R3    <- oops!

The problem was that promoting R3 = load[ss#2] to a copy missed the fact that
the instruction invalidated R3 at that point.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23638 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-10-05 18:30:19 +00:00
parent f5c6e6b745
commit 22480c4350
1 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
lib/CodeGen/VirtRegMap.cpp
View File

@ -490,11 +490,11 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM) {
if (DestReg != It->second) { if (DestReg != It->second) {
MRI->copyRegToReg(MBB, &MI, DestReg, It->second, MRI->copyRegToReg(MBB, &MI, DestReg, It->second,
MF.getSSARegMap()->getRegClass(VirtReg)); MF.getSSARegMap()->getRegClass(VirtReg));
// Revisit the copy if the destination is a vreg. // Revisit the copy so we make sure to notice the effects of the
if (MRegisterInfo::isVirtualRegister(DestReg)) { // operation on the destreg (either needing to RA it if it's
NextMII = &MI; // virtual or needing to clobber any values if it's physical).
--NextMII; // backtrack to the copy. NextMII = &MI;
} --NextMII; // backtrack to the copy.
} }
MBB.erase(&MI); MBB.erase(&MI);
goto ProcessNextInst; goto ProcessNextInst;