[RegAllocGreedy][Last Chance Recoloring] Addition of
-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>.
llvm-svn: 206072
diff --git a/llvm/lib/CodeGen/RegAllocGreedy.cpp b/llvm/lib/CodeGen/RegAllocGreedy.cpp
index e65398f..7a120e8 100644
--- a/llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ b/llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -73,6 +73,11 @@
" 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 @@
// 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 @@
// 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 @@
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;
}