1 /* -----------------------------------------------------------------------------
3 * (c) The GHC Team, 1998-2004
5 * Code to perform updates.
7 * This file is written in a subset of C--, extended with various
8 * features specific to GHC. It is compiled by GHC directly. For the
9 * syntax of .cmm files, see the parser in ghc/compiler/cmm/CmmParse.y.
11 * ---------------------------------------------------------------------------*/
16 #include "StgLdvProf.h"
19 The update frame return address must be *polymorphic*, that means
20 we have to cope with both vectored and non-vectored returns. This
21 is done by putting the return vector right before the info table, and
22 having a standard direct return address after the info table (pointed
23 to by the return address itself, as usual).
25 Each entry in the vector table points to a specialised entry code fragment
26 that knows how to return after doing the update. It would be possible to
27 use a single generic piece of code that simply entered the return value
28 to return, but it's quicker this way. The direct return code of course
29 just does another direct return when it's finished.
32 /* on entry to the update code
33 (1) R1 points to the closure being returned
34 (2) Sp points to the update frame
37 /* The update fragment has been tuned so as to generate good
38 code with gcc, which accounts for some of the strangeness in the
41 In particular, the JMP_(ret) bit is passed down and pinned on the
42 end of each branch (there end up being two major branches in the
43 code), since we don't mind duplicating this jump.
46 #define UPD_FRAME_ENTRY_TEMPLATE(label,ind_info,ret) \
51 updatee = StgUpdateFrame_updatee(Sp); \
53 /* remove the update frame from the stack */ \
54 Sp = Sp + SIZEOF_StgUpdateFrame; \
56 /* ToDo: it might be a PAP, so we should check... */ \
57 TICK_UPD_CON_IN_NEW(sizeW_fromITBL(%GET_STD_INFO(updatee))); \
59 UPD_SPEC_IND(updatee, ind_info, R1, jump (ret)); \
62 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_0_ret,stg_IND_0_info,%RET_VEC(Sp(0),0))
63 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_1_ret,stg_IND_1_info,%RET_VEC(Sp(0),1))
64 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_2_ret,stg_IND_2_info,%RET_VEC(Sp(0),2))
65 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_3_ret,stg_IND_3_info,%RET_VEC(Sp(0),3))
66 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_4_ret,stg_IND_4_info,%RET_VEC(Sp(0),4))
67 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_5_ret,stg_IND_5_info,%RET_VEC(Sp(0),5))
68 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_6_ret,stg_IND_6_info,%RET_VEC(Sp(0),6))
69 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_7_ret,stg_IND_7_info,%RET_VEC(Sp(0),7))
71 #if MAX_VECTORED_RTN > 8
72 #error MAX_VECTORED_RTN has changed: please modify stg_upd_frame too.
76 Make sure this table is big enough to handle the maximum vectored
80 #if defined(PROFILING)
81 #define UPD_FRAME_BITMAP 3
82 #define UPD_FRAME_WORDS 3
84 #define UPD_FRAME_BITMAP 0
85 #define UPD_FRAME_WORDS 1
88 /* this bitmap indicates that the first word of an update frame is a
89 * non-pointer - this is the update frame link. (for profiling,
90 * there's a cost-centre-stack in there too).
93 INFO_TABLE_RET( stg_upd_frame,
94 UPD_FRAME_WORDS, UPD_FRAME_BITMAP, UPDATE_FRAME,
104 UPD_FRAME_ENTRY_TEMPLATE(,stg_IND_direct_info,%ENTRY_CODE(Sp(0)))
107 INFO_TABLE_RET( stg_marked_upd_frame,
108 UPD_FRAME_WORDS, UPD_FRAME_BITMAP, UPDATE_FRAME,
118 UPD_FRAME_ENTRY_TEMPLATE(,stg_IND_direct_info,%ENTRY_CODE(Sp(0)))
120 /*-----------------------------------------------------------------------------
123 We don't have a primitive seq# operator: it is just a 'case'
124 expression whose scrutinee has either a polymorphic or function type
125 (constructor types can be handled by normal 'case' expressions).
127 To handle a polymorphic/function typed seq, we push a SEQ frame on
128 the stack. This is a polymorphic activation record that just pops
129 itself and returns (in a non-vectored way) when entered. The
130 purpose of the SEQ frame is to avoid having to make a polymorphic return
131 point for each polymorphic case expression.
133 Another way of looking at it: the SEQ frame turns a vectored return
135 -------------------------------------------------------------------------- */
137 #if MAX_VECTORED_RTN > 8
138 #error MAX_VECTORED_RTN has changed: please modify stg_seq_frame too.
141 INFO_TABLE_RET( stg_seq_frame, 0/* words */, 0/* bitmap */, RET_SMALL,
142 RET_LBL(stg_seq_frame), /* 0 */
143 RET_LBL(stg_seq_frame), /* 1 */
144 RET_LBL(stg_seq_frame), /* 2 */
145 RET_LBL(stg_seq_frame), /* 3 */
146 RET_LBL(stg_seq_frame), /* 4 */
147 RET_LBL(stg_seq_frame), /* 5 */
148 RET_LBL(stg_seq_frame), /* 6 */
149 RET_LBL(stg_seq_frame) /* 7 */
153 jump %ENTRY_CODE(Sp(0));