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cmd/compile: fix SIMD const rematerialization condition

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This CL fixes a condition for the previous fix CL 704056.

Cherry-picked from the dev.simd branch. This CL is not
necessarily SIMD specific. Apply early to reduce risk. Test is
SIMD specific so not included for now.

Change-Id: I1f1f8c6f72870403cb3dff14755c43385dc0c933
Reviewed-on: https://go-review.googlesource.com/c/go/+/705499
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/708864
Reviewed-by: David Chase <drchase@google.com>
This commit is contained in:
Junyang Shao 2025-09-19 18:38:25 +00:00 • committed by Cherry Mui
parent d91148c7a8
commit 003b5ce1bc
1 changed files with 10 additions and 7 deletions
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17
src/cmd/compile/internal/ssa/regalloc.go
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@ -2561,22 +2561,25 @@ func (e *edgeState) processDest(loc Location, vid ID, splice **Value, pos src.XP
e.s.f.Fatalf("can't find source for %s->%s: %s\n", e.p, e.b, v.LongString()) e.s.f.Fatalf("can't find source for %s->%s: %s\n", e.p, e.b, v.LongString())
} }
if dstReg { if dstReg {
// Handle incompatible registers. // We want to rematerialize v into a register that is incompatible with v's op's register mask.
// Instead of setting the wrong register for the rematerialized v, we should find the right register
// for it and emit an additional copy to move to the desired register.
// For #70451. // For #70451.
if e.s.regspec(v).outputs[0].regs&regMask(1<<register(loc.(*Register).num)) == 0 && c != nil { if e.s.regspec(v).outputs[0].regs&regMask(1<<register(loc.(*Register).num)) == 0 {
_, srcReg := src.(*Register) _, srcReg := src.(*Register)
if !srcReg { if srcReg {
// It exists in a valid register already, so just copy it to the desired register
// If src is a Register, c must have already been set.
x = e.p.NewValue1(pos, OpCopy, c.Type, c)
} else {
// We need a tmp register // We need a tmp register
x = v.copyInto(e.p) x = v.copyInto(e.p)
r := e.findRegFor(x.Type) r := e.findRegFor(x.Type)
e.erase(r) e.erase(r)
// Rematerialize to a tmp register // Rematerialize to the tmp register
e.set(r, vid, x, false, pos) e.set(r, vid, x, false, pos)
// Copy from tmp to the desired register // Copy from tmp to the desired register
x = e.p.NewValue1(pos, OpCopy, x.Type, x) x = e.p.NewValue1(pos, OpCopy, x.Type, x)
} else {
// It exist in a valid register already, so just copy it to the desired register
x = e.p.NewValue1(pos, OpCopy, c.Type, c)
} }
} else { } else {
x = v.copyInto(e.p) x = v.copyInto(e.p)