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cmd/compile,runtime: provide index information on bounds check failure

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A few examples (for accessing a slice of length 3):

   s[-1]    runtime error: index out of range [-1]
   s[3]     runtime error: index out of range [3] with length 3
   s[-1:0]  runtime error: slice bounds out of range [-1:]
   s[3:0]   runtime error: slice bounds out of range [3:0]
   s[3:-1]  runtime error: slice bounds out of range [:-1]
   s[3:4]   runtime error: slice bounds out of range [:4] with capacity 3
   s[0:3:4] runtime error: slice bounds out of range [::4] with capacity 3

Note that in cases where there are multiple things wrong with the
indexes (e.g. s[3:-1]), we report one of those errors kind of
arbitrarily, currently the rightmost one.

An exhaustive set of examples is in issue30116[u].out in the CL.

The message text has the same prefix as the old message text. That
leads to slightly awkward phrasing but hopefully minimizes the chance
that code depending on the error text will break.

Increases the size of the go binary by 0.5% (amd64). The panic functions
take arguments in registers in order to keep the size of the compiled code
as small as possible.

Fixes #30116

Change-Id: Idb99a827b7888822ca34c240eca87b7e44a04fdd
Reviewed-on: https://go-review.googlesource.com/c/go/+/161477
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
This commit is contained in:
Keith Randall 2019-02-06 14:12:36 -08:00 • committed by Keith Randall
parent b48bda9c6f
commit 2c423f063b
59 changed files with 4464 additions and 355 deletions
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14
src/cmd/compile/internal/x86/ssa.go
View file

@ -758,6 +758,20 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
p.To.Name = obj.NAME_EXTERN
p.To.Sym = v.Aux.(*obj.LSym)
case ssa.Op386LoweredPanicBoundsA, ssa.Op386LoweredPanicBoundsB, ssa.Op386LoweredPanicBoundsC:
p := s.Prog(obj.ACALL)
p.To.Type = obj.TYPE_MEM
p.To.Name = obj.NAME_EXTERN
p.To.Sym = gc.BoundsCheckFunc[v.AuxInt]
s.UseArgs(8) // space used in callee args area by assembly stubs
case ssa.Op386LoweredPanicExtendA, ssa.Op386LoweredPanicExtendB, ssa.Op386LoweredPanicExtendC:
p := s.Prog(obj.ACALL)
p.To.Type = obj.TYPE_MEM
p.To.Name = obj.NAME_EXTERN
p.To.Sym = gc.ExtendCheckFunc[v.AuxInt]
s.UseArgs(12) // space used in callee args area by assembly stubs
case ssa.Op386CALLstatic, ssa.Op386CALLclosure, ssa.Op386CALLinter:
s.Call(v)
case ssa.Op386NEGL,