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Fix Regression/CodeGen/Generic/2006-09-02-LocalAllocCrash.ll on X86.

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Just because an alias of a register is available, it doesn't mean that we
can arbitrarily evict the register.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30064 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-09-03 07:15:37 +00:00
parent 6cfca76349
commit 5e50349070
1 changed files with 11 additions and 6 deletions
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17
lib/CodeGen/RegAllocLocal.cpp
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@ -103,8 +103,8 @@ namespace {
}
void MarkPhysRegRecentlyUsed(unsigned Reg) {
if(PhysRegsUseOrder.empty() ||
PhysRegsUseOrder.back() == Reg) return; // Already most recently used
if (PhysRegsUseOrder.empty() ||
PhysRegsUseOrder.back() == Reg) return; // Already most recently used
for (unsigned i = PhysRegsUseOrder.size(); i != 0; --i)
if (areRegsEqual(Reg, PhysRegsUseOrder[i-1])) {
@ -408,10 +408,15 @@ unsigned RA::getReg(MachineBasicBlock &MBB, MachineInstr *I,
} else {
// If one of the registers aliased to the current register is
// compatible, use it.
for (const unsigned *AliasSet = RegInfo->getAliasSet(R);
*AliasSet; ++AliasSet) {
if (RC->contains(*AliasSet)) {
PhysReg = *AliasSet; // Take an aliased register
for (const unsigned *AliasIt = RegInfo->getAliasSet(R);
*AliasIt; ++AliasIt) {
if (RC->contains(*AliasIt) &&
// If this is pinned down for some reason, don't use it. For
// example, if CL is pinned, and we run across CH, don't use
// CH as justification for using scavenging ECX (which will
// fail).
PhysRegsUsed[*AliasIt] != 0) {
PhysReg = *AliasIt; // Take an aliased register
break;
}
}