Andrew Trick 6ea2b9608a Allocate local registers in order for optimal coloring. ... Also avoid locals evicting locals just because they want a cheaper register. Problem: MI Sched knows exactly how many registers we have and assumes they can be colored. In cases where we have large blocks, usually from unrolled loops, greedy coloring fails. This is a source of "regressions" from the MI Scheduler on x86. I noticed this issue on x86 where we have long chains of two-address defs in the same live range. It's easy to see this in matrix multiplication benchmarks like IRSmk and even the unit test misched-matmul.ll. A fundamental difference between the LLVM register allocator and conventional graph coloring is that in our model a live range can't discover its neighbors, it can only verify its neighbors. That's why we initially went for greedy coloring and added eviction to deal with the hard cases. However, for singly defined and two-address live ranges, we can optimally color without visiting neighbors simply by processing the live ranges in instruction order. Other beneficial side effects: It is much easier to understand and debug regalloc for large blocks when the live ranges are allocated in order. Yes, global allocation is still very confusing, but it's nice to be able to comprehend what happened locally. Heuristics could be added to bias register assignment based on instruction locality (think late register pairing, banks...). Intuituvely this will make some test cases that are on the threshold of register pressure more stable. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187139 91177308-0d34-0410-b5e6-96231b3b80d8		2013-07-25 18:35:14 +00:00
..
64abi.ll	Sparc: Perform leaf procedure optimization by default	2013-06-02 02:24:27 +00:00
64bit.ll	Mass update to CodeGen tests to use CHECK-LABEL for labels corresponding to function definitions for more informative error messages. No functionality change and all updated tests passed locally.	2013-07-14 06:24:09 +00:00
64cond.ll	Allocate local registers in order for optimal coloring.	2013-07-25 18:35:14 +00:00
2006-01-22-BitConvertLegalize.ll
2007-05-09-JumpTables.ll
2007-07-05-LiveIntervalAssert.ll
2008-10-10-InlineAsmMemoryOperand.ll
2008-10-10-InlineAsmRegOperand.ll
2009-08-28-PIC.ll
2009-08-28-WeakLinkage.ll
2011-01-11-Call.ll
2011-01-11-CC.ll	Update to more CodeGen tests to use CHECK-LABEL for labels corresponding to function definitions for more informative error messages. No functionality change.	2013-07-18 22:47:09 +00:00
2011-01-11-FrameAddr.ll	Update to more CodeGen tests to use CHECK-LABEL for labels corresponding to function definitions for more informative error messages. No functionality change.	2013-07-18 22:47:09 +00:00
2011-01-19-DelaySlot.ll	Update to more CodeGen tests to use CHECK-LABEL for labels corresponding to function definitions for more informative error messages. No functionality change.	2013-07-18 22:47:09 +00:00
2011-01-21-ByValArgs.ll	Update to more CodeGen tests to use CHECK-LABEL for labels corresponding to function definitions for more informative error messages. No functionality change.	2013-07-18 22:47:09 +00:00
2011-01-22-SRet.ll	Update to more CodeGen tests to use CHECK-LABEL for labels corresponding to function definitions for more informative error messages. No functionality change.	2013-07-18 22:47:09 +00:00
2011-12-03-TailDuplication.ll
2012-05-01-LowerArguments.ll
2013-05-17-CallFrame.ll	[Sparc] Implements hasReservedCallFrame and hasFP.	2013-05-17 15:14:34 +00:00
basictest.ll	Mass update to CodeGen tests to use CHECK-LABEL for labels corresponding to function definitions for more informative error messages. No functionality change and all updated tests passed locally.	2013-07-14 06:24:09 +00:00
blockaddr.ll	Mass update to CodeGen tests to use CHECK-LABEL for labels corresponding to function definitions for more informative error messages. No functionality change and all updated tests passed locally.	2013-07-14 06:24:09 +00:00
constpool.ll	Sparc: Perform leaf procedure optimization by default	2013-06-02 02:24:27 +00:00
ctpop.ll	Add support for 64-bit calling convention.	2013-04-02 04:09:02 +00:00
DbgValueOtherTargets.test	Remove unnecessary leading comment characters in lit-only file	2013-03-18 22:08:16 +00:00
float.ll	Mass update to CodeGen tests to use CHECK-LABEL for labels corresponding to function definitions for more informative error messages. No functionality change and all updated tests passed locally.	2013-07-14 06:24:09 +00:00
globals.ll	Sparc: Perform leaf procedure optimization by default	2013-06-02 02:24:27 +00:00
leafproc.ll	Mass update to CodeGen tests to use CHECK-LABEL for labels corresponding to function definitions for more informative error messages. No functionality change and all updated tests passed locally.	2013-07-14 06:24:09 +00:00
lit.local.cfg
mult-alt-generic-sparc.ll
private.ll
varargs.ll	Sparc: Mark functions calling llvm.vastart and llvm.returnaddress intrinsics as non-leaf functions.	2013-06-01 20:42:48 +00:00