From d2f958d8d11bcf62fe572885133bfaef41307a14 Mon Sep 17 00:00:00 2001 From: Cuong Manh Le Date: Tue, 3 Sep 2019 23:24:35 +0700 Subject: cmd/compile: extend ssa.go to handle 1-element array and 1-field struct Assinging to 1-element array/1-field struct variable is considered clobbering the whole variable. By emitting OpVarDef in this case, liveness analysis can now know the variable is redefined. Also, the isfat is not necessary anymore, and will be removed in follow up CL. Fixes #33916 Change-Id: Iece0d90b05273f333d59d6ee5b12ee7dc71908c2 Reviewed-on: https://go-review.googlesource.com/c/go/+/192979 Run-TryBot: Cuong Manh Le TryBot-Result: Gobot Gobot Reviewed-by: Matthew Dempsky --- src/cmd/compile/internal/gc/ssa.go | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) (limited to 'src') diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go index ac7f3eb22b..0706d95937 100644 --- a/src/cmd/compile/internal/gc/ssa.go +++ b/src/cmd/compile/internal/gc/ssa.go @@ -2767,10 +2767,14 @@ func (s *state) assign(left *Node, right *ssa.Value, deref bool, skip skipMask) s.addNamedValue(left, right) return } - // Left is not ssa-able. Compute its address. - if left.Op == ONAME && left.Class() != PEXTERN && skip == 0 { - s.vars[&memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, left, s.mem(), !left.IsAutoTmp()) + + // If this assignment clobbers an entire local variable, then emit + // OpVarDef so liveness analysis knows the variable is redefined. + if base := clobberBase(left); base.Op == ONAME && base.Class() != PEXTERN && skip == 0 { + s.vars[&memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, base, s.mem(), !base.IsAutoTmp()) } + + // Left is not ssa-able. Compute its address. addr := s.addr(left, false) if isReflectHeaderDataField(left) { // Package unsafe's documentation says storing pointers into @@ -6210,3 +6214,13 @@ func (n *Node) StorageClass() ssa.StorageClass { return 0 } } + +func clobberBase(n *Node) *Node { + if n.Op == ODOT && n.Left.Type.NumFields() == 1 { + return clobberBase(n.Left) + } + if n.Op == OINDEX && n.Left.Type.IsArray() && n.Left.Type.NumElem() == 1 { + return clobberBase(n.Left) + } + return n +} -- cgit v1.3-5-g9baa