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cmd/compile: crash if we try to generate a truncated AMD64 const shift

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This turn misscompilations like #79182 into ICEs which are
immensely easier to catch and less silently problematic.

Change-Id: Ifaa136d3f36734abdfad9e204b5d713274f6bb4e
Reviewed-on: https://go-review.googlesource.com/c/go/+/774041
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Jorropo <jorropo.pgm@gmail.com>
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Jorropo 2026-05-05 00:39:28 +02:00 • committed by Gopher Robot
parent c3bfc824a5
commit f2b1b38293
1 changed files with 24 additions and 2 deletions
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26
src/cmd/compile/internal/amd64/ssa.go
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@ -700,11 +700,33 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
case ssa.OpAMD64SUBQconst, ssa.OpAMD64SUBLconst,
ssa.OpAMD64ANDLconst,
ssa.OpAMD64ORQconst, ssa.OpAMD64ORLconst,
ssa.OpAMD64XORQconst, ssa.OpAMD64XORLconst,
ssa.OpAMD64SHLQconst, ssa.OpAMD64SHLLconst,
ssa.OpAMD64XORQconst, ssa.OpAMD64XORLconst:
p := s.Prog(v.Op.Asm())
p.From.Type = obj.TYPE_CONST
p.From.Offset = v.AuxInt
p.To.Type = obj.TYPE_REG
p.To.Reg = v.Reg()
case ssa.OpAMD64SHLQconst, ssa.OpAMD64SHLLconst,
ssa.OpAMD64SHRQconst, ssa.OpAMD64SHRLconst, ssa.OpAMD64SHRWconst, ssa.OpAMD64SHRBconst,
ssa.OpAMD64SARQconst, ssa.OpAMD64SARLconst, ssa.OpAMD64SARWconst, ssa.OpAMD64SARBconst,
ssa.OpAMD64ROLQconst, ssa.OpAMD64ROLLconst, ssa.OpAMD64ROLWconst, ssa.OpAMD64ROLBconst:
var maxShift int64
switch v.Op {
case ssa.OpAMD64SHLQconst, ssa.OpAMD64SHRQconst, ssa.OpAMD64SARQconst, ssa.OpAMD64ROLQconst:
maxShift = 63
case ssa.OpAMD64SHLLconst, ssa.OpAMD64SHRLconst, ssa.OpAMD64SARLconst, ssa.OpAMD64ROLLconst:
maxShift = 31
case ssa.OpAMD64SHRWconst, ssa.OpAMD64SARWconst, ssa.OpAMD64ROLWconst:
maxShift = 15
case ssa.OpAMD64SHRBconst, ssa.OpAMD64SARBconst, ssa.OpAMD64ROLBconst:
maxShift = 7
default:
panic("unreachable")
}
if v.AuxInt < 0 || v.AuxInt > maxShift {
v.Fatalf("shift amount out of range [0,%d]: %d", maxShift, v.AuxInt)
}
p := s.Prog(v.Op.Asm())
p.From.Type = obj.TYPE_CONST
p.From.Offset = v.AuxInt