From a690a5d75fee3b23e9ab80bd7b48cafb52ce4615 Mon Sep 17 00:00:00 2001 From: David Chase Date: Wed, 7 Apr 2021 09:58:02 -0400 Subject: [PATCH] cmd/compile: ensure spills of int/float reg args land in abi slots We noticed a while ago that register argument spills were not always landing where they should. Updates #40724. Change-Id: I0b7c3279a2f6270577481c252bae4568cbb6e796 Reviewed-on: https://go-review.googlesource.com/c/go/+/308510 Trust: David Chase Run-TryBot: David Chase Reviewed-by: Cherry Zhang --- src/cmd/compile/internal/ssa/stackalloc.go | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/src/cmd/compile/internal/ssa/stackalloc.go b/src/cmd/compile/internal/ssa/stackalloc.go index 45058d4e720..025396f335e 100644 --- a/src/cmd/compile/internal/ssa/stackalloc.go +++ b/src/cmd/compile/internal/ssa/stackalloc.go @@ -218,8 +218,15 @@ func (s *stackAllocState) stackalloc() { // If this is a named value, try to use the name as // the spill location. var name LocalSlot + interfere := false if v.Op == OpStoreReg { - name = names[v.Args[0].ID] + a := v.Args[0] + name = names[a.ID] + if name.N == nil && (a.Op == OpArgIntReg || a.Op == OpArgFloatReg) { + // Try harder to spill to the abi-provided spill slot, even if the names are messed up. + nameOff := a.Aux.(*AuxNameOffset) + name = LocalSlot{N: nameOff.Name, Type: v.Type, Off: nameOff.Offset} + } } else { name = names[v.ID] } @@ -230,6 +237,7 @@ func (s *stackAllocState) stackalloc() { // A variable can interfere with itself. // It is rare, but it can happen. s.nSelfInterfere++ + interfere = true goto noname } } @@ -271,7 +279,11 @@ func (s *stackAllocState) stackalloc() { // Use the stack variable at that index for v. loc := locs[i] if f.pass.debug > stackDebug { - fmt.Printf("stackalloc %s to %s\n", v, loc) + reason := "noname" + if interfere { + reason = "interfere" + } + fmt.Printf("stackalloc (%s) %s to %s\n", reason, v, loc) } f.setHome(v, loc) slots[v.ID] = i