Improve promotion of double-precision regs
Minor rework of the double allocation mechanism to more explicitly
manage the allocation of preserved floating point single pairs as
doubles.
Change-Id: Id9db4b0e86e5ef54a5db587f367e00efdf7e98d6
diff --git a/compiler/dex/quick/mir_to_lir.h b/compiler/dex/quick/mir_to_lir.h
index fdbc1d0..401e3d5 100644
--- a/compiler/dex/quick/mir_to_lir.h
+++ b/compiler/dex/quick/mir_to_lir.h
@@ -158,6 +158,10 @@
#define ENCODE_ALL (~0ULL)
#define ENCODE_MEM (ENCODE_DALVIK_REG | ENCODE_LITERAL | \
ENCODE_HEAP_REF | ENCODE_MUST_NOT_ALIAS)
+
+// Mask to denote sreg as the start of a double. Must not interfere with low 16 bits.
+#define STARTING_DOUBLE_SREG 0x10000
+
// TODO: replace these macros
#define SLOW_FIELD_PATH (cu_->enable_debug & (1 << kDebugSlowFieldPath))
#define SLOW_INVOKE_PATH (cu_->enable_debug & (1 << kDebugSlowInvokePath))
@@ -187,7 +191,6 @@
struct RefCounts {
int count;
int s_reg;
- bool double_start; // Starting v_reg for a double
};
/*
@@ -324,11 +327,9 @@
void RecordCorePromotion(int reg, int s_reg);
int AllocPreservedCoreReg(int s_reg);
void RecordFpPromotion(int reg, int s_reg);
- int AllocPreservedSingle(int s_reg, bool even);
+ int AllocPreservedSingle(int s_reg);
int AllocPreservedDouble(int s_reg);
- int AllocPreservedFPReg(int s_reg, bool double_start);
- int AllocTempBody(RegisterInfo* p, int num_regs, int* next_temp,
- bool required);
+ int AllocTempBody(RegisterInfo* p, int num_regs, int* next_temp, bool required);
int AllocTempDouble();
int AllocFreeTemp();
int AllocTemp();
@@ -367,7 +368,7 @@
RegLocation UpdateRawLoc(RegLocation loc);
RegLocation EvalLocWide(RegLocation loc, int reg_class, bool update);
RegLocation EvalLoc(RegLocation loc, int reg_class, bool update);
- void CountRefs(RefCounts* core_counts, RefCounts* fp_counts);
+ void CountRefs(RefCounts* core_counts, RefCounts* fp_counts, size_t num_regs);
void DumpCounts(const RefCounts* arr, int size, const char* msg);
void DoPromotion();
int VRegOffset(int v_reg);
diff --git a/compiler/dex/quick/ralloc_util.cc b/compiler/dex/quick/ralloc_util.cc
index a0f22fc..7927ff9 100644
--- a/compiler/dex/quick/ralloc_util.cc
+++ b/compiler/dex/quick/ralloc_util.cc
@@ -174,17 +174,12 @@
promotion_map_[p_map_idx].FpReg = reg;
}
-/*
- * Reserve a callee-save fp single register. Try to fullfill request for
- * even/odd allocation, but go ahead and allocate anything if not
- * available. If nothing's available, return -1.
- */
-int Mir2Lir::AllocPreservedSingle(int s_reg, bool even) {
- int res = -1;
+// Reserve a callee-save fp single register.
+int Mir2Lir::AllocPreservedSingle(int s_reg) {
+ int res = -1; // Return code if none available.
RegisterInfo* FPRegs = reg_pool_->FPRegs;
for (int i = 0; i < reg_pool_->num_fp_regs; i++) {
- if (!FPRegs[i].is_temp && !FPRegs[i].in_use &&
- ((FPRegs[i].reg & 0x1) == 0) == even) {
+ if (!FPRegs[i].is_temp && !FPRegs[i].in_use) {
res = FPRegs[i].reg;
RecordFpPromotion(res, s_reg);
break;
@@ -250,26 +245,6 @@
return res;
}
-
-/*
- * Reserve a callee-save fp register. If this register can be used
- * as the first of a double, attempt to allocate an even pair of fp
- * single regs (but if can't still attempt to allocate a single, preferring
- * first to allocate an odd register.
- */
-int Mir2Lir::AllocPreservedFPReg(int s_reg, bool double_start) {
- int res = -1;
- if (double_start) {
- res = AllocPreservedDouble(s_reg);
- }
- if (res == -1) {
- res = AllocPreservedSingle(s_reg, false /* try odd # */);
- }
- if (res == -1)
- res = AllocPreservedSingle(s_reg, true /* try even # */);
- return res;
-}
-
int Mir2Lir::AllocTempBody(RegisterInfo* p, int num_regs, int* next_temp,
bool required) {
int next = *next_temp;
@@ -872,18 +847,22 @@
}
/* USE SSA names to count references of base Dalvik v_regs. */
-void Mir2Lir::CountRefs(RefCounts* core_counts, RefCounts* fp_counts) {
+void Mir2Lir::CountRefs(RefCounts* core_counts, RefCounts* fp_counts, size_t num_regs) {
for (int i = 0; i < mir_graph_->GetNumSSARegs(); i++) {
RegLocation loc = mir_graph_->reg_location_[i];
RefCounts* counts = loc.fp ? fp_counts : core_counts;
int p_map_idx = SRegToPMap(loc.s_reg_low);
- // Don't count easily regenerated immediates
- if (loc.fp || !IsInexpensiveConstant(loc)) {
+ if (loc.fp) {
+ if (loc.wide) {
+ // Treat doubles as a unit, using upper half of fp_counts array.
+ counts[p_map_idx + num_regs].count += mir_graph_->GetUseCount(i);
+ i++;
+ } else {
+ counts[p_map_idx].count += mir_graph_->GetUseCount(i);
+ }
+ } else if (!IsInexpensiveConstant(loc)) {
counts[p_map_idx].count += mir_graph_->GetUseCount(i);
}
- if (loc.wide && loc.fp && !loc.high_word) {
- counts[p_map_idx].double_start = true;
- }
}
}
@@ -902,7 +881,11 @@
void Mir2Lir::DumpCounts(const RefCounts* arr, int size, const char* msg) {
LOG(INFO) << msg;
for (int i = 0; i < size; i++) {
- LOG(INFO) << "s_reg[" << arr[i].s_reg << "]: " << arr[i].count;
+ if ((arr[i].s_reg & STARTING_DOUBLE_SREG) != 0) {
+ LOG(INFO) << "s_reg[D" << (arr[i].s_reg & ~STARTING_DOUBLE_SREG) << "]: " << arr[i].count;
+ } else {
+ LOG(INFO) << "s_reg[" << arr[i].s_reg << "]: " << arr[i].count;
+ }
}
}
@@ -925,7 +908,7 @@
* count based on original Dalvik register name. Count refs
* separately based on type in order to give allocation
* preference to fp doubles - which must be allocated sequential
- * physical single fp registers started with an even-numbered
+ * physical single fp registers starting with an even-numbered
* reg.
* TUNING: replace with linear scan once we have the ability
* to describe register live ranges for GC.
@@ -934,7 +917,7 @@
static_cast<RefCounts*>(arena_->Alloc(sizeof(RefCounts) * num_regs,
ArenaAllocator::kAllocRegAlloc));
RefCounts *FpRegs =
- static_cast<RefCounts *>(arena_->Alloc(sizeof(RefCounts) * num_regs,
+ static_cast<RefCounts *>(arena_->Alloc(sizeof(RefCounts) * num_regs * 2,
ArenaAllocator::kAllocRegAlloc));
// Set ssa names for original Dalvik registers
for (int i = 0; i < dalvik_regs; i++) {
@@ -942,46 +925,49 @@
}
// Set ssa name for Method*
core_regs[dalvik_regs].s_reg = mir_graph_->GetMethodSReg();
- FpRegs[dalvik_regs].s_reg = mir_graph_->GetMethodSReg(); // For consistecy
+ FpRegs[dalvik_regs].s_reg = mir_graph_->GetMethodSReg(); // For consistecy.
+ FpRegs[dalvik_regs + num_regs].s_reg = mir_graph_->GetMethodSReg(); // for consistency.
// Set ssa names for compiler_temps
for (int i = 1; i <= cu_->num_compiler_temps; i++) {
CompilerTemp* ct = mir_graph_->compiler_temps_.Get(i);
core_regs[dalvik_regs + i].s_reg = ct->s_reg;
FpRegs[dalvik_regs + i].s_reg = ct->s_reg;
+ FpRegs[num_regs + dalvik_regs + i].s_reg = ct->s_reg;
+ }
+
+ // Duplicate in upper half to represent possible fp double starting sregs.
+ for (int i = 0; i < num_regs; i++) {
+ FpRegs[num_regs + i].s_reg = FpRegs[i].s_reg | STARTING_DOUBLE_SREG;
}
// Sum use counts of SSA regs by original Dalvik vreg.
- CountRefs(core_regs, FpRegs);
+ CountRefs(core_regs, FpRegs, num_regs);
- /*
- * Ideally, we'd allocate doubles starting with an even-numbered
- * register. Bias the counts to try to allocate any vreg that's
- * used as the start of a pair first.
- */
- for (int i = 0; i < num_regs; i++) {
- if (FpRegs[i].double_start) {
- FpRegs[i].count *= 2;
- }
- }
// Sort the count arrays
qsort(core_regs, num_regs, sizeof(RefCounts), SortCounts);
- qsort(FpRegs, num_regs, sizeof(RefCounts), SortCounts);
+ qsort(FpRegs, num_regs * 2, sizeof(RefCounts), SortCounts);
if (cu_->verbose) {
DumpCounts(core_regs, num_regs, "Core regs after sort");
- DumpCounts(FpRegs, num_regs, "Fp regs after sort");
+ DumpCounts(FpRegs, num_regs * 2, "Fp regs after sort");
}
if (!(cu_->disable_opt & (1 << kPromoteRegs))) {
// Promote FpRegs
- for (int i = 0; (i < num_regs) && (FpRegs[i].count >= promotion_threshold); i++) {
- int p_map_idx = SRegToPMap(FpRegs[i].s_reg);
- if (promotion_map_[p_map_idx].fp_location != kLocPhysReg) {
- int reg = AllocPreservedFPReg(FpRegs[i].s_reg,
- FpRegs[i].double_start);
+ for (int i = 0; (i < (num_regs * 2)) && (FpRegs[i].count >= promotion_threshold); i++) {
+ int p_map_idx = SRegToPMap(FpRegs[i].s_reg & ~STARTING_DOUBLE_SREG);
+ if ((FpRegs[i].s_reg & STARTING_DOUBLE_SREG) != 0) {
+ if ((promotion_map_[p_map_idx].fp_location != kLocPhysReg) &&
+ (promotion_map_[p_map_idx + 1].fp_location != kLocPhysReg)) {
+ int low_sreg = FpRegs[i].s_reg & ~STARTING_DOUBLE_SREG;
+ // Ignore result - if can't alloc double may still be able to alloc singles.
+ AllocPreservedDouble(low_sreg);
+ }
+ } else if (promotion_map_[p_map_idx].fp_location != kLocPhysReg) {
+ int reg = AllocPreservedSingle(FpRegs[i].s_reg);
if (reg < 0) {
- break; // No more left
+ break; // No more left.
}
}
}
