Let each target determines whether a machine instruction is dead. If true, that allows late codeine passes to delete it.

This is considered a workaround. The problem is some targets are not modeling side effects correctly. PPC is apparently one of those. This patch allows ppc llvm-gcc to bootstrap on Darwin. Once we find out which instruction definitions are wrong, we can remove the PPCInstrInfo workaround.

llvm-svn: 76703

Another rewriter bug exposed by recent coalescer changes. ReuseInfo::GetRegForReload() should make sure the "switched" register is in the desired register class. I'm surprised this hasn't caused more failures in the past.

llvm-svn: 76558

llvm-svn: 76281

llvm-svn: 76131

llvm-svn: 76123

llvm-svn: 76111

llvm-svn: 76100

Avoid remat'ing instructions whose def have sub-register indices for now. It's just really really hard to get all the cases right.

llvm-svn: 75900

This adds location info for all llvm_unreachable calls (which is a macro now) in
!NDEBUG builds.
In NDEBUG builds location info and the message is off (it only prints
"UREACHABLE executed").

llvm-svn: 75640

Make llvm_unreachable take an optional string, thus moving the cerr<< out of
line.
LLVM_UNREACHABLE is now a simple wrapper that makes the message go away for
NDEBUG builds.

llvm-svn: 75379

Remove TargetInstrInfo::CommuteChangesDestination and added findCommutedOpIndices which returns the operand indices which are swapped (when applicable). This allows for some code clean up and future enhancements.

llvm-svn: 75264

Handle IMPLICIT_DEF with isUndef operand marker, part 2. This patch moves the code to annotate machineoperands to LiveIntervalAnalysis. It also add markers for implicit_def that define physical registers. The rest, is just a lot of details.

llvm-svn: 74580

Add a bit IsUndef to MachineOperand. This indicates the def / use register operand is defined by an implicit_def. That means it can def / use any register and passes (e.g. register scavenger) can feel free to ignore them.

The register allocator, when it allocates a register to a virtual register defined by an implicit_def, can allocate any physical register without worrying about overlapping live ranges. It should mark all of operands of the said virtual register so later passes will do the right thing.

This is not the best solution. But it should be a lot less fragile to having the scavenger try to track what is defined by implicit_def.

llvm-svn: 74518

llvm-svn: 72880

Fix for PR4225: When rewriter reuse a value in a physical register , it clear the register kill operand marker and its kill ops information. However, the cleared operand may be a def of a super-register. Clear the kill ops info for the super-register's sub-registers as well.

llvm-svn: 72758

llvm-svn: 72729

llvm-svn: 71848

llvm-svn: 71606

llvm-svn: 71057