cmd/compile: handle rematerialized op for incompatible reg constraint

This CL fixes an issue raised by contributor dominikh@.

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: I941b330a6ba6f6c120c69951ddd24933f2f0b3ec
Reviewed-on: https://go-review.googlesource.com/c/go/+/704056
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/708861
This commit is contained in:
Junyang Shao 2025-09-16 03:27:41 +00:00 committed by Cherry Mui
parent 18cd4a1fc7
commit ad3db2562e

View file

@ -2561,7 +2561,26 @@ 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())
}
if dstReg {
x = v.copyInto(e.p)
// Handle incompatible registers.
// For #70451.
if e.s.regspec(v).outputs[0].regs&regMask(1<<register(loc.(*Register).num)) == 0 && c != nil {
_, srcReg := src.(*Register)
if !srcReg {
// We need a tmp register
x = v.copyInto(e.p)
r := e.findRegFor(x.Type)
e.erase(r)
// Rematerialize to a tmp register
e.set(r, vid, x, false, pos)
// Copy from tmp to the desired register
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 {
x = v.copyInto(e.p)
}
} else {
// Rematerialize into stack slot. Need a free
// register to accomplish this.