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[RegAllocGreedy][Last Chance Recoloring] Addition of

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-fexhaustive-register-search option to allow an exhaustive search during last
chance recoloring.

This is related to PR18747

Patch by MAYUR PANDEY <mayur.p@samsung.com>. 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206072 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Quentin Colombet 2014-04-11 21:39:44 +00:00
parent 4aee5942c3
commit 92a892e8f9
2 changed files with 19 additions and 6 deletions
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20
lib/CodeGen/RegAllocGreedy.cpp
View File

@ -73,6 +73,11 @@ static cl::opt<unsigned> LastChanceRecoloringMaxInterference(
" interference at a time"),
cl::init(8));
static cl::opt<bool>
ExhaustiveSearch("fexhaustive-register-search", cl::NotHidden,
cl::desc("Exhaustive Search for registers bypassing the depth "
"and interference cutoffs of last chance recoloring"));
// FIXME: Find a good default for this flag and remove the flag.
static cl::opt<unsigned>
CSRFirstTimeCost("regalloc-csr-first-time-cost",
@ -1932,7 +1937,7 @@ RAGreedy::mayRecolorAllInterferences(unsigned PhysReg, LiveInterval &VirtReg,
// If there is LastChanceRecoloringMaxInterference or more interferences,
// chances are one would not be recolorable.
if (Q.collectInterferingVRegs(LastChanceRecoloringMaxInterference) >=
LastChanceRecoloringMaxInterference) {
LastChanceRecoloringMaxInterference && !ExhaustiveSearch) {
DEBUG(dbgs() << "Early abort: too many interferences.\n");
CutOffInfo |= CO_Interf;
return false;
@ -2005,7 +2010,7 @@ unsigned RAGreedy::tryLastChanceRecoloring(LiveInterval &VirtReg,
// We may want to reconsider that if we end up with a too large search space
// for target with hundreds of registers.
// Indeed, in that case we may want to cut the search space earlier.
if (Depth >= LastChanceRecoloringMaxDepth) {
if (Depth >= LastChanceRecoloringMaxDepth && !ExhaustiveSearch) {
DEBUG(dbgs() << "Abort because max depth has been reached.\n");
CutOffInfo |= CO_Depth;
return ~0u;
@ -2139,14 +2144,17 @@ unsigned RAGreedy::selectOrSplit(LiveInterval &VirtReg,
if (Reg == ~0U && (CutOffInfo != CO_None)) {
uint8_t CutOffEncountered = CutOffInfo & (CO_Depth | CO_Interf);
if (CutOffEncountered == CO_Depth)
Ctx.emitError(
"register allocation failed: maximum depth for recoloring reached");
Ctx.emitError("register allocation failed: maximum depth for recoloring "
"reached. Use -fexhaustive-register-search to skip "
"cutoffs");
else if (CutOffEncountered == CO_Interf)
Ctx.emitError("register allocation failed: maximum interference for "
"recoloring reached");
"recoloring reached. Use -fexhaustive-register-search "
"to skip cutoffs");
else if (CutOffEncountered == (CO_Depth | CO_Interf))
Ctx.emitError("register allocation failed: maximum interference and "
"depth for recoloring reached");
"depth for recoloring reached. Use "
"-fexhaustive-register-search to skip cutoffs");
}
return Reg;
}

5
test/CodeGen/X86/ragreedy-last-chance-recoloring.ll
View File

@ -8,6 +8,10 @@
; RUN: not llc -regalloc=greedy -relocation-model=pic -lcr-max-interf=1 < %s 2>&1 | FileCheck %s --check-prefix=CHECK-INTERF
; Test whether failure due to cutoff for interference is reported
; RUN: llc -regalloc=greedy -relocation-model=pic -lcr-max-interf=1 -lcr-max-depth=0 -fexhaustive-register-search < %s > %t 2>&1
; RUN: FileCheck --input-file=%t %s --check-prefix=CHECK-EXHAUSTIVE
; Test whether fexhaustive-register-search can bypass the depth and interference cutoffs of last chance recoloring
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32-S128"
target triple = "i386-apple-macosx"
@ -20,6 +24,7 @@ target triple = "i386-apple-macosx"
; CHECK-NOT: ran out of registers during register allocation
; CHECK-INTERF: error: register allocation failed: maximum interference for recoloring reached
; CHECK-DEPTH: error: register allocation failed: maximum depth for recoloring reached
; CHECK-EXHAUSTIVE-NOT: error: register allocation failed: maximum {{depth|interference}} for recoloring reached
define void @fp_dh_f870bf31fd8ffe068450366e3f05389a(i8* %arg) #0 {
bb:
indirectbr i8* undef, [label %bb85, label %bb206]