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regalloc: eliminates unnecessary Instr loop (#2258)

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Signed-off-by: Takeshi Yoneda <t.y.mathetake@gmail.com>
This commit is contained in:
Takeshi Yoneda
2024-06-18 11:31:57 -07:00
committed by GitHub
parent 54cee893da
commit c6ffc9edd1
1 changed files with 22 additions and 21 deletions
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43
internal/engine/wazevo/backend/regalloc/regalloc.go
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@@ -57,6 +57,7 @@ type (
allocatedCalleeSavedRegs []VReg allocatedCalleeSavedRegs []VReg
vs []VReg vs []VReg
vs2 []VRegID vs2 []VRegID
is []Instr
phiDefInstListPool wazevoapi.Pool[phiDefInstList] phiDefInstListPool wazevoapi.Pool[phiDefInstList]
// Followings are re-used during various places. // Followings are re-used during various places.
@@ -660,6 +661,7 @@ func (a *Allocator) allocBlock(f Function, blk Block) {
desiredUpdated := a.vs2[:0] desiredUpdated := a.vs2[:0]
// Update the last use of each VReg. // Update the last use of each VReg.
a.is = a.is[:0] // Stores the copy instructions.
var pc programCounter var pc programCounter
for instr := blk.InstrIteratorBegin(); instr != nil; instr = blk.InstrIteratorNext() { for instr := blk.InstrIteratorBegin(); instr != nil; instr = blk.InstrIteratorNext() {
var use, def VReg var use, def VReg
@@ -670,6 +672,7 @@ func (a *Allocator) allocBlock(f Function, blk Block) {
} }
if instr.IsCopy() { if instr.IsCopy() {
a.is = append(a.is, instr)
def = instr.Defs(&a.vs)[0] def = instr.Defs(&a.vs)[0]
r := def.RealReg() r := def.RealReg()
if r != RealRegInvalid { if r != RealRegInvalid {
@@ -722,22 +725,20 @@ func (a *Allocator) allocBlock(f Function, blk Block) {
} }
// Propagate the desired register values from the end of the block to the beginning. // Propagate the desired register values from the end of the block to the beginning.
for instr := blk.InstrRevIteratorBegin(); instr != nil; instr = blk.InstrRevIteratorNext() { for _, instr := range a.is {
if instr.IsCopy() { def := instr.Defs(&a.vs)[0]
def := instr.Defs(&a.vs)[0] defState := s.getVRegState(def.ID())
defState := s.getVRegState(def.ID()) desired := defState.desiredLoc.realReg()
desired := defState.desiredLoc.realReg() if desired == RealRegInvalid {
if desired == RealRegInvalid { continue
continue }
}
use := instr.Uses(&a.vs)[0] use := instr.Uses(&a.vs)[0]
useID := use.ID() useID := use.ID()
useState := s.getVRegState(useID) useState := s.getVRegState(useID)
if s.phiBlk(useID) != succ && useState.desiredLoc == desiredLocUnspecified { if s.phiBlk(useID) != succ && useState.desiredLoc == desiredLocUnspecified {
useState.desiredLoc = newDesiredLocReg(desired) useState.desiredLoc = newDesiredLocReg(desired)
desiredUpdated = append(desiredUpdated, useID) desiredUpdated = append(desiredUpdated, useID)
}
} }
} }
@@ -796,10 +797,9 @@ func (a *Allocator) allocBlock(f Function, blk Block) {
} }
isIndirect := instr.IsIndirectCall() isIndirect := instr.IsIndirectCall()
call := instr.IsCall() || isIndirect if instr.IsCall() || isIndirect {
if call {
addr := RealRegInvalid addr := RealRegInvalid
if instr.IsIndirectCall() { if isIndirect {
addr = a.vs[0].RealReg() addr = a.vs[0].RealReg()
} }
a.releaseCallerSavedRegs(addr) a.releaseCallerSavedRegs(addr)
@@ -811,8 +811,8 @@ func (a *Allocator) allocBlock(f Function, blk Block) {
a.reals = killSet a.reals = killSet
defs := instr.Defs(&a.vs) defs := instr.Defs(&a.vs)
switch { switch len(defs) {
case len(defs) > 1: default:
// Some instructions define multiple values on real registers. // Some instructions define multiple values on real registers.
// E.g. call instructions (following calling convention) / div instruction on x64 that defines both rax and rdx. // E.g. call instructions (following calling convention) / div instruction on x64 that defines both rax and rdx.
// //
@@ -829,7 +829,8 @@ func (a *Allocator) allocBlock(f Function, blk Block) {
} }
s.useRealReg(r, def) s.useRealReg(r, def)
} }
case len(defs) == 1: case 0:
case 1:
def := defs[0] def := defs[0]
if def.IsRealReg() { if def.IsRealReg() {
r := def.RealReg() r := def.RealReg()