diff options
Diffstat (limited to 'lib/CodeGen/RegAllocLinearScan.cpp')
| -rw-r--r-- | lib/CodeGen/RegAllocLinearScan.cpp | 24 |
1 files changed, 22 insertions, 2 deletions
diff --git a/lib/CodeGen/RegAllocLinearScan.cpp b/lib/CodeGen/RegAllocLinearScan.cpp index d43cc19683..12e7d6a697 100644 --- a/lib/CodeGen/RegAllocLinearScan.cpp +++ b/lib/CodeGen/RegAllocLinearScan.cpp @@ -561,6 +561,7 @@ void RALinScan::assignRegOrStackSlotAtInterval(LiveInterval* cur) // is very bad (it contains all callee clobbered registers for any functions // with a call), so we want to avoid doing that if possible. unsigned physReg = getFreePhysReg(cur); + unsigned BestPhysReg = physReg; if (physReg) { // We got a register. However, if it's in the fixed_ list, we might // conflict with it. Check to see if we conflict with it or any of its @@ -685,8 +686,27 @@ void RALinScan::assignRegOrStackSlotAtInterval(LiveInterval* cur) } // All registers must have inf weight. Just grab one! - if (!minReg) - minReg = *RC->allocation_order_begin(*mf_); + if (!minReg) { + if (BestPhysReg) + minReg = BestPhysReg; + else { + // Get the physical register with the fewest conflicts. + unsigned MinConflicts = ~0U; + for (TargetRegisterClass::iterator i = RC->allocation_order_begin(*mf_), + e = RC->allocation_order_end(*mf_); i != e; ++i) { + unsigned reg = *i; + unsigned NumConflicts = li_->getNumConflictsWithPhysReg(*cur, reg); + if (NumConflicts <= MinConflicts) { + MinConflicts = NumConflicts; + minReg = reg; + } + } + } + + if (cur->weight == HUGE_VALF || cur->getSize() == 1) + // Spill a physical register around defs and uses. + li_->spillPhysRegAroundRegDefsUses(*cur, minReg, *vrm_); + } } DOUT << "\t\tregister with min weight: " |