diff options
Diffstat (limited to 'src/cmd/compile/internal/ssa/gen/AMD64Ops.go')
| -rw-r--r-- | src/cmd/compile/internal/ssa/gen/AMD64Ops.go | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ssa/gen/AMD64Ops.go b/src/cmd/compile/internal/ssa/gen/AMD64Ops.go index de5372670b..a87581b68f 100644 --- a/src/cmd/compile/internal/ssa/gen/AMD64Ops.go +++ b/src/cmd/compile/internal/ssa/gen/AMD64Ops.go @@ -358,6 +358,11 @@ func init() { {name: "BTSQconst", argLength: 1, reg: gp11, asm: "BTSQ", resultInArg0: true, clobberFlags: true, aux: "Int8"}, // set bit auxint in arg0, 0 <= auxint < 64 // direct bit operation on memory operand + // + // Note that these operations do not mask the bit offset (arg1), and will write beyond their expected + // bounds if that argument is larger than 64/32 (for BT*Q and BT*L, respectively). If the compiler + // cannot prove that arg1 is in range, it must be explicitly masked (see e.g. the patterns that produce + // BT*modify from (MOVstore (BT* (MOVLload ptr mem) x) mem)). {name: "BTCQmodify", argLength: 3, reg: gpstore, asm: "BTCQ", aux: "SymOff", typ: "Mem", clobberFlags: true, faultOnNilArg0: true, symEffect: "Read,Write"}, // complement bit arg1 in 64-bit arg0+auxint+aux, arg2=mem {name: "BTCLmodify", argLength: 3, reg: gpstore, asm: "BTCL", aux: "SymOff", typ: "Mem", clobberFlags: true, faultOnNilArg0: true, symEffect: "Read,Write"}, // complement bit arg1 in 32-bit arg0+auxint+aux, arg2=mem {name: "BTSQmodify", argLength: 3, reg: gpstore, asm: "BTSQ", aux: "SymOff", typ: "Mem", clobberFlags: true, faultOnNilArg0: true, symEffect: "Read,Write"}, // set bit arg1 in 64-bit arg0+auxint+aux, arg2=mem |