regalloc: removes unnecessary Instruction.Uses (#2237)

This also early stops resetting IDedPool. ### Zig stdlib ``` goos: darwin goarch: arm64 pkg: github.com/tetratelabs/wazero │ old_zig.txt │ new_zig.txt │ │ sec/op │ sec/op vs base │ Compilation-10 4.540 ± 0% 4.380 ± 1% -3.51% (p=0.001 n=7) │ old_zig.txt │ new_zig.txt │ │ B/op │ B/op vs base │ Compilation-10 599.3Mi ± 0% 599.3Mi ± 0% ~ (p=0.383 n=7) │ old_zig.txt │ new_zig.txt │ │ allocs/op │ allocs/op vs base │ Compilation-10 288.0k ± 0% 288.0k ± 0% ~ (p=0.805 n=7) ``` ### wazero compiled as a wasip1 binary ``` goos: darwin goarch: arm64 pkg: github.com/tetratelabs/wazero │ old.txt │ new.txt │ │ sec/op │ sec/op vs base │ Compilation-10 2.264 ± 1% 2.224 ± 0% -1.80% (p=0.001 n=7) │ old.txt │ new.txt │ │ B/op │ B/op vs base │ Compilation-10 337.3Mi ± 0% 337.3Mi ± 0% ~ (p=0.318 n=7) │ old.txt │ new.txt │ │ allocs/op │ allocs/op vs base │ Compilation-10 593.7k ± 0% 593.6k ± 0% ~ (p=0.456 n=7) ``` Signed-off-by: Takeshi Yoneda <[email protected]>
tetratelabs · Jun 7, 2024 · 9995367 · 9995367
1 parent 0649820
commit 9995367
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diff --git a/internal/engine/wazevo/backend/regalloc/regalloc.go b/internal/engine/wazevo/backend/regalloc/regalloc.go
@@ -754,7 +754,8 @@ func (a *Allocator) allocBlock(f Function, blk Block) {
 		killSet := a.reals[:0]
 
 		// Gather the set of registers that will be used in the current instruction.
-		for _, use := range instr.Uses(&a.vs) {
+		uses := instr.Uses(&a.vs)
+		for _, use := range uses {
 			if use.IsRealReg() {
 				r := use.RealReg()
 				currentUsedSet = currentUsedSet.add(r)
@@ -769,7 +770,7 @@ func (a *Allocator) allocBlock(f Function, blk Block) {
 			}
 		}
 
-		for i, use := range instr.Uses(&a.vs) {
+		for i, use := range uses {
 			if !use.IsRealReg() {
 				vs := s.getVRegState(use.ID())
 				killed := vs.lastUse == pc

diff --git a/internal/engine/wazevo/wazevoapi/pool.go b/internal/engine/wazevo/wazevoapi/pool.go
@@ -69,7 +69,7 @@ type IDedPool[T any] struct {
 
 // NewIDedPool returns a new IDedPool.
 func NewIDedPool[T any](resetFn func(*T)) IDedPool[T] {
-	return IDedPool[T]{pool: NewPool[T](resetFn)}
+	return IDedPool[T]{pool: NewPool[T](resetFn), maxIDEncountered: -1}
 }
 
 // GetOrAllocate returns the T with the given id.
@@ -97,7 +97,7 @@ func (p *IDedPool[T]) Get(id int) *T {
 // Reset resets the pool.
 func (p *IDedPool[T]) Reset() {
 	p.pool.Reset()
-	for i := range p.idToItems {
+	for i := 0; i <= p.maxIDEncountered; i++ {
 		p.idToItems[i] = nil
 	}
 	p.maxIDEncountered = -1