diff options
Diffstat (limited to 'src/cmd/compile/internal/ssa/_gen/generic.rules')
| -rw-r--r-- | src/cmd/compile/internal/ssa/_gen/generic.rules | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ssa/_gen/generic.rules b/src/cmd/compile/internal/ssa/_gen/generic.rules index ccdb1d8a77..0fc0f54433 100644 --- a/src/cmd/compile/internal/ssa/_gen/generic.rules +++ b/src/cmd/compile/internal/ssa/_gen/generic.rules @@ -2539,6 +2539,13 @@ (SelectN [0] call:(StaticLECall {sym} a x)) && needRaceCleanup(sym, call) && clobber(call) => x (SelectN [0] call:(StaticLECall {sym} x)) && needRaceCleanup(sym, call) && clobber(call) => x +// When rewriting append to growslice, we use as the the new length the result of +// growslice so that we don't have to spill/restore the new length around the growslice call. +// The exception here is that if the new length is a constant, avoiding spilling it +// is pointless and its constantness is sometimes useful for subsequent optimizations. +// See issue 56440. +(SliceLen (SelectN [0] (StaticLECall {sym} _ newLen:(Const(64|32)) _ _ _ _))) && isSameCall(sym, "runtime.growslice") => newLen + // Collapse moving A -> B -> C into just A -> C. // Later passes (deadstore, elim unread auto) will remove the A -> B move, if possible. // This happens most commonly when B is an autotmp inserted earlier |