1 /* -----------------------------------------------------------------------------
2 * $Id: Updates.hc,v 1.41 2003/07/28 15:57:40 simonmar Exp $
4 * (c) The GHC Team, 1998-2002
6 * Code to perform updates.
8 * ---------------------------------------------------------------------------*/
15 #if defined(GRAN) || defined(PAR)
20 The update frame return address must be *polymorphic*, that means
21 we have to cope with both vectored and non-vectored returns. This
22 is done by putting the return vector right before the info table, and
23 having a standard direct return address after the info table (pointed
24 to by the return address itself, as usual).
26 Each entry in the vector table points to a specialised entry code fragment
27 that knows how to return after doing the update. It would be possible to
28 use a single generic piece of code that simply entered the return value
29 to return, but it's quicker this way. The direct return code of course
30 just does another direct return when it's finished.
33 /* on entry to the update code
34 (1) R1 points to the closure being returned
35 (2) Sp points to the update frame
38 /* The update fragment has been tuned so as to generate reasonable
39 code with gcc, which accounts for some of the strangeness in the
42 In particular, the JMP_(ret) bit is passed down and pinned on the
43 end of each branch (there end up being two major branches in the
44 code), since we don't mind duplicating this jump.
47 #define UPD_FRAME_ENTRY_TEMPLATE(label,ind_info,ret) \
51 StgClosure *updatee; \
54 updatee = ((StgUpdateFrame *)Sp)->updatee; \
56 /* remove the update frame from the stack */ \
57 Sp += sizeofW(StgUpdateFrame); \
59 /* ToDo: it might be a PAP, so we should check... */ \
60 TICK_UPD_CON_IN_NEW(sizeW_fromITBL(get_itbl(updatee))); \
62 UPD_SPEC_IND(updatee, ind_info, R1.cl, JMP_(ret)); \
66 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_ret,&stg_IND_direct_info,ENTRY_CODE(Sp[0]));
67 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_0_ret,&stg_IND_0_info,RET_VEC(Sp[0],0));
68 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_1_ret,&stg_IND_1_info,RET_VEC(Sp[0],1));
69 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_2_ret,&stg_IND_2_info,RET_VEC(Sp[0],2));
70 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_3_ret,&stg_IND_3_info,RET_VEC(Sp[0],3));
71 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_4_ret,&stg_IND_4_info,RET_VEC(Sp[0],4));
72 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_5_ret,&stg_IND_5_info,RET_VEC(Sp[0],5));
73 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_6_ret,&stg_IND_6_info,RET_VEC(Sp[0],6));
74 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_7_ret,&stg_IND_7_info,RET_VEC(Sp[0],7));
77 Make sure this table is big enough to handle the maximum vectored
81 #if defined(PROFILING)
82 #define UPD_FRAME_BITMAP 3
83 #define UPD_FRAME_WORDS 3
85 #define UPD_FRAME_BITMAP 0
86 #define UPD_FRAME_WORDS 1
89 /* this bitmap indicates that the first word of an update frame is a
90 * non-pointer - this is the update frame link. (for profiling,
91 * there's a cost-centre-stack in there too).
94 VEC_POLY_INFO_TABLE( stg_upd_frame,
95 MK_SMALL_BITMAP(UPD_FRAME_WORDS, UPD_FRAME_BITMAP),
96 0/*srt*/, 0/*srt_off*/, 0/*srt_bitmap*/,
99 /*-----------------------------------------------------------------------------
102 We don't have a primitive seq# operator: it is just a 'case'
103 expression whose scrutinee has either a polymorphic or function type
104 (constructor types can be handled by normal 'case' expressions).
106 To handle a polymorphic/function typed seq, we push a SEQ frame on
107 the stack. This is a polymorphic activation record that just pops
108 itself and returns (in a non-vectored way) when entered. The
109 purpose of the SEQ frame is to avoid having to make a polymorphic return
110 point for each polymorphic case expression.
112 Another way of looking at it: the SEQ frame turns a vectored return
114 -------------------------------------------------------------------------- */
116 IF_(stg_seq_frame_ret);
118 #define stg_seq_frame_0_ret stg_seq_frame_ret
119 #define stg_seq_frame_1_ret stg_seq_frame_ret
120 #define stg_seq_frame_2_ret stg_seq_frame_ret
121 #define stg_seq_frame_3_ret stg_seq_frame_ret
122 #define stg_seq_frame_4_ret stg_seq_frame_ret
123 #define stg_seq_frame_5_ret stg_seq_frame_ret
124 #define stg_seq_frame_6_ret stg_seq_frame_ret
125 #define stg_seq_frame_7_ret stg_seq_frame_ret
127 VEC_POLY_INFO_TABLE( stg_seq_frame,
128 MK_SMALL_BITMAP(0, 0),
129 0/*srt*/, 0/*srt_off*/, 0/*srt_bitmap*/,
132 IF_(stg_seq_frame_ret)
136 JMP_(ENTRY_CODE(Sp[0]));