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[dev.regabi] cmd/compile: fix reporting of overflow
In the previous CL, I had incorrectly removed one of the error messages from issue20232.go, because I thought go/constant was just handling it. But actually the compiler was panicking in nodlit, because it didn't handle constant.Unknown. So this CL makes it leave n.Type == nil for unknown constant.Values. While here, also address #42732 by making sure to report an error message when origConst is called with an unknown constant.Value (as can happen when multiplying two floating-point constants overflows). Finally, add OXOR and OBITNOT to the list of operations to report errors about, since they're also constant expressions that can produce a constant with a greater bit length than their operands. Fixes #42732. Change-Id: I4a538fbae9b3ac4c553d7de5625dc0c87d9acce3 Reviewed-on: https://go-review.googlesource.com/c/go/+/272928 Trust: Matthew Dempsky <mdempsky@google.com> Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Russ Cox <rsc@golang.org>
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@ -718,11 +718,14 @@ func square(x constant.Value) constant.Value {
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}
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// For matching historical "constant OP overflow" error messages.
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// TODO(mdempsky): Replace with error messages like go/types uses.
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var overflowNames = [...]string{
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OADD: "addition",
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OSUB: "subtraction",
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OMUL: "multiplication",
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OLSH: "shift",
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OADD: "addition",
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OSUB: "subtraction",
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OMUL: "multiplication",
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OLSH: "shift",
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OXOR: "bitwise XOR",
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OBITNOT: "bitwise complement",
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}
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// origConst returns an OLITERAL with orig n and value v.
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@ -732,32 +735,24 @@ func origConst(n *Node, v constant.Value) *Node {
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lineno = lno
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switch v.Kind() {
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case constant.Unknown:
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// If constant folding was attempted (we were called)
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// but it produced an invalid constant value,
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// mark n as broken and give up.
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if Errors() == 0 {
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Fatalf("should have reported an error")
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case constant.Int:
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if constant.BitLen(v) <= Mpprec {
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break
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}
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fallthrough
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case constant.Unknown:
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what := overflowNames[n.Op]
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if what == "" {
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Fatalf("unexpected overflow: %v", n.Op)
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}
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yyerrorl(n.Pos, "constant %v overflow", what)
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n.Type = nil
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return n
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case constant.Int:
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if constant.BitLen(v) > Mpprec {
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what := overflowNames[n.Op]
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if what == "" {
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Fatalf("unexpected overflow: %v", n.Op)
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}
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yyerror("constant %v overflow", what)
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n.Type = nil
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return n
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}
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}
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orig := n
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n = nod(OLITERAL, nil, nil)
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n = nodl(orig.Pos, OLITERAL, nil, nil)
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n.Orig = orig
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n.Pos = orig.Pos
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n.Type = orig.Type
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n.SetVal(v)
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return n
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@ -800,8 +795,10 @@ func origIntConst(n *Node, v int64) *Node {
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// nodlit returns a new untyped constant with value v.
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func nodlit(v constant.Value) *Node {
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n := nod(OLITERAL, nil, nil)
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n.Type = idealType(v.Kind())
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n.SetVal(v)
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if k := v.Kind(); k != constant.Unknown {
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n.Type = idealType(k)
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n.SetVal(v)
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}
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return n
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}
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@ -19,3 +19,14 @@ const LargeB = LargeA * LargeA * LargeA
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const LargeC = LargeB * LargeB * LargeB // GC_ERROR "constant multiplication overflow"
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const AlsoLargeA = LargeA << 400 << 400 >> 400 >> 400 // GC_ERROR "constant shift overflow"
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// Issue #42732.
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const a = 1e+500000000
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const b = a * a // ERROR "constant multiplication overflow"
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const c = b * b
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const MaxInt512 = (1<<256 - 1) * (1<<256 + 1)
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const _ = MaxInt512 + 1 // ERROR "constant addition overflow"
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const _ = MaxInt512 ^ -1 // ERROR "constant bitwise XOR overflow"
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const _ = ^MaxInt512 // ERROR "constant bitwise complement overflow"
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@ -6,6 +6,7 @@
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package main
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const _ = 6e5518446744 // ERROR "malformed constant: 6e5518446744"
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const x = 6e5518446744 // ERROR "malformed constant: 6e5518446744"
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const _ = x * x
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const _ = 1e-1000000000
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const _ = 1e+1000000000
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const _ = 1e+1000000000 // ERROR "malformed constant: 1e\+1000000000"
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