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| author | Cuong Manh Le <cuong.manhle.vn@gmail.com> | 2019-09-03 23:24:35 +0700 |
|---|---|---|
| committer | Matthew Dempsky <mdempsky@google.com> | 2019-09-03 19:33:04 +0000 |
| commit | d2f958d8d11bcf62fe572885133bfaef41307a14 (patch) | |
| tree | 043de28a03afa2f716e8bdfb8e226f8bc9e31c53 /src | |
| parent | 9da7abd2ebd07d32484277adac75c45b66f504c1 (diff) | |
| download | go-d2f958d8d11bcf62fe572885133bfaef41307a14.tar.xz | |
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 <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/cmd/compile/internal/gc/ssa.go | 20 |
1 files changed, 17 insertions, 3 deletions
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 +} |