diff options
| -rw-r--r-- | src/synth/synth-expr.adb | 56 |
1 files changed, 32 insertions, 24 deletions
diff --git a/src/synth/synth-expr.adb b/src/synth/synth-expr.adb index 82b7766a8..408845d3a 100644 --- a/src/synth/synth-expr.adb +++ b/src/synth/synth-expr.adb @@ -1273,6 +1273,7 @@ package body Synth.Expr is Off : out Uns32; Wd : out Width) is + Is_Null : Boolean; Len : Uns32; begin if Pfx_Bnd.Dir /= Dir then @@ -1282,34 +1283,41 @@ package body Synth.Expr is return; end if; - if not In_Bounds (Pfx_Bnd, Int32 (L)) - or else not In_Bounds (Pfx_Bnd, Int32 (R)) - then - Error_Msg_Synth (+Name, "index not within bounds"); - Synth.Debugger.Debug_Error (Syn_Inst, Expr); - Wd := 0; - Off := 0; - return; - end if; - + -- Might be a null slice. case Pfx_Bnd.Dir is when Iir_To => - Len := Uns32 (R - L + 1); - Res_Bnd := (Dir => Iir_To, - Wbounds => Pfx_Bnd.Wbounds, - Len => Len, - Left => Int32 (L), - Right => Int32 (R)); - Off := Uns32 (Pfx_Bnd.Right - Res_Bnd.Right) * El_Wd; + Is_Null := L > R; when Iir_Downto => - Len := Uns32 (L - R + 1); - Res_Bnd := (Dir => Iir_Downto, - Wbounds => Pfx_Bnd.Wbounds, - Len => Len, - Left => Int32 (L), - Right => Int32 (R)); - Off := Uns32 (Res_Bnd.Right - Pfx_Bnd.Right) * El_Wd; + Is_Null := L < R; end case; + if Is_Null then + Len := 0; + Off := 0; + else + if not In_Bounds (Pfx_Bnd, Int32 (L)) + or else not In_Bounds (Pfx_Bnd, Int32 (R)) + then + Error_Msg_Synth (+Name, "index not within bounds"); + Synth.Debugger.Debug_Error (Syn_Inst, Expr); + Wd := 0; + Off := 0; + return; + end if; + + case Pfx_Bnd.Dir is + when Iir_To => + Len := Uns32 (R - L + 1); + Off := Uns32 (Pfx_Bnd.Right - Int32 (R)) * El_Wd; + when Iir_Downto => + Len := Uns32 (L - R + 1); + Off := Uns32 (Int32 (R) - Pfx_Bnd.Right) * El_Wd; + end case; + end if; + Res_Bnd := (Dir => Pfx_Bnd.Dir, + Wbounds => Pfx_Bnd.Wbounds, + Len => Len, + Left => Int32 (L), + Right => Int32 (R)); Wd := Len * El_Wd; end Synth_Slice_Const_Suffix; |