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 * ---------------------------------------------------------------------------*/
15 #include "StgLdvProf.h"
18 The update frame return address must be *polymorphic*, that means
19 we have to cope with both vectored and non-vectored returns. This
20 is done by putting the return vector right before the info table, and
21 having a standard direct return address after the info table (pointed
22 to by the return address itself, as usual).
24 Each entry in the vector table points to a specialised entry code fragment
25 that knows how to return after doing the update. It would be possible to
26 use a single generic piece of code that simply entered the return value
27 to return, but it's quicker this way. The direct return code of course
28 just does another direct return when it's finished.
31 /* on entry to the update code
32 (1) R1 points to the closure being returned
33 (2) Sp points to the update frame
36 /* The update fragment has been tuned so as to generate good
37 code with gcc, which accounts for some of the strangeness in the
40 In particular, the JMP_(ret) bit is passed down and pinned on the
41 end of each branch (there end up being two major branches in the
42 code), since we don't mind duplicating this jump.
45 #define UPD_FRAME_ENTRY_TEMPLATE(label,ind_info,ret) \
50 updatee = StgUpdateFrame_updatee(Sp); \
52 /* remove the update frame from the stack */ \
53 Sp = Sp + SIZEOF_StgUpdateFrame; \
55 /* ToDo: it might be a PAP, so we should check... */ \
56 TICK_UPD_CON_IN_NEW(sizeW_fromITBL(%GET_STD_INFO(updatee))); \
58 NOBH_UPD_SPEC_IND(updatee, ind_info, R1, jump (ret)); \
61 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_0_ret,stg_IND_0_info,%RET_VEC(Sp(0),0))
62 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_1_ret,stg_IND_1_info,%RET_VEC(Sp(0),1))
63 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_2_ret,stg_IND_2_info,%RET_VEC(Sp(0),2))
64 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_3_ret,stg_IND_3_info,%RET_VEC(Sp(0),3))
65 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_4_ret,stg_IND_4_info,%RET_VEC(Sp(0),4))
66 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_5_ret,stg_IND_5_info,%RET_VEC(Sp(0),5))
67 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_6_ret,stg_IND_6_info,%RET_VEC(Sp(0),6))
68 UPD_FRAME_ENTRY_TEMPLATE(stg_upd_frame_7_ret,stg_IND_7_info,%RET_VEC(Sp(0),7))
70 #if MAX_VECTORED_RTN > 8
71 #error MAX_VECTORED_RTN has changed: please modify stg_upd_frame too.
75 Make sure this table is big enough to handle the maximum vectored
79 #if defined(PROFILING)
80 #define UPD_FRAME_BITMAP 3
81 #define UPD_FRAME_WORDS 3
83 #define UPD_FRAME_BITMAP 0
84 #define UPD_FRAME_WORDS 1
87 /* this bitmap indicates that the first word of an update frame is a
88 * non-pointer - this is the update frame link. (for profiling,
89 * there's a cost-centre-stack in there too).
92 INFO_TABLE_RET( stg_upd_frame,
93 UPD_FRAME_WORDS, UPD_FRAME_BITMAP, UPDATE_FRAME,
103 UPD_FRAME_ENTRY_TEMPLATE(,stg_IND_direct_info,%ENTRY_CODE(Sp(0)))
105 /* -----------------------------------------------------------------------------
106 * Update frames that check for BLACKHOLE_BQ
108 * A normal update frame doesn't check whether the closure has been
109 * overwritten with BLACKHOLE_BQ, because it can't until lazy blackholing
110 * has happened. Lazy blackholing overwrites the update frames pointing
111 * to BLACKHOLE with stg_bh_upd_frame_info.
112 * -------------------------------------------------------------------------- */
114 #define BH_UPD_FRAME_ENTRY_TEMPLATE(label,ind_info,ret) \
119 updatee = StgUpdateFrame_updatee(Sp); \
121 /* remove the update frame from the stack */ \
122 Sp = Sp + SIZEOF_StgUpdateFrame; \
124 /* ToDo: it might be a PAP, so we should check... */ \
125 TICK_UPD_CON_IN_NEW(sizeW_fromITBL(%GET_STD_INFO(updatee))); \
127 UPD_SPEC_IND(updatee, ind_info, R1, jump (ret)); \
130 BH_UPD_FRAME_ENTRY_TEMPLATE(stg_bh_upd_frame_0_ret,stg_IND_0_info,%RET_VEC(Sp(0),0))
131 BH_UPD_FRAME_ENTRY_TEMPLATE(stg_bh_upd_frame_1_ret,stg_IND_1_info,%RET_VEC(Sp(0),1))
132 BH_UPD_FRAME_ENTRY_TEMPLATE(stg_bh_upd_frame_2_ret,stg_IND_2_info,%RET_VEC(Sp(0),2))
133 BH_UPD_FRAME_ENTRY_TEMPLATE(stg_bh_upd_frame_3_ret,stg_IND_3_info,%RET_VEC(Sp(0),3))
134 BH_UPD_FRAME_ENTRY_TEMPLATE(stg_bh_upd_frame_4_ret,stg_IND_4_info,%RET_VEC(Sp(0),4))
135 BH_UPD_FRAME_ENTRY_TEMPLATE(stg_bh_upd_frame_5_ret,stg_IND_5_info,%RET_VEC(Sp(0),5))
136 BH_UPD_FRAME_ENTRY_TEMPLATE(stg_bh_upd_frame_6_ret,stg_IND_6_info,%RET_VEC(Sp(0),6))
137 BH_UPD_FRAME_ENTRY_TEMPLATE(stg_bh_upd_frame_7_ret,stg_IND_7_info,%RET_VEC(Sp(0),7))
139 #if MAX_VECTORED_RTN > 8
140 #error MAX_VECTORED_RTN has changed: please modify stg_bh_upd_frame too.
143 /* this bitmap indicates that the first word of an update frame is a
144 * non-pointer - this is the update frame link. (for profiling,
145 * there's a cost-centre-stack in there too).
148 INFO_TABLE_RET( stg_bh_upd_frame,
149 UPD_FRAME_WORDS, UPD_FRAME_BITMAP, UPDATE_FRAME,
150 stg_bh_upd_frame_0_ret,
151 stg_bh_upd_frame_1_ret,
152 stg_bh_upd_frame_2_ret,
153 stg_bh_upd_frame_3_ret,
154 stg_bh_upd_frame_4_ret,
155 stg_bh_upd_frame_5_ret,
156 stg_bh_upd_frame_6_ret,
157 stg_bh_upd_frame_7_ret
159 UPD_FRAME_ENTRY_TEMPLATE(,stg_IND_direct_info,%ENTRY_CODE(Sp(0)))
161 /*-----------------------------------------------------------------------------
164 We don't have a primitive seq# operator: it is just a 'case'
165 expression whose scrutinee has either a polymorphic or function type
166 (constructor types can be handled by normal 'case' expressions).
168 To handle a polymorphic/function typed seq, we push a SEQ frame on
169 the stack. This is a polymorphic activation record that just pops
170 itself and returns (in a non-vectored way) when entered. The
171 purpose of the SEQ frame is to avoid having to make a polymorphic return
172 point for each polymorphic case expression.
174 Another way of looking at it: the SEQ frame turns a vectored return
176 -------------------------------------------------------------------------- */
178 #if MAX_VECTORED_RTN > 8
179 #error MAX_VECTORED_RTN has changed: please modify stg_seq_frame too.
182 INFO_TABLE_RET( stg_seq_frame, 0/* words */, 0/* bitmap */, RET_SMALL,
183 RET_LBL(stg_seq_frame), /* 0 */
184 RET_LBL(stg_seq_frame), /* 1 */
185 RET_LBL(stg_seq_frame), /* 2 */
186 RET_LBL(stg_seq_frame), /* 3 */
187 RET_LBL(stg_seq_frame), /* 4 */
188 RET_LBL(stg_seq_frame), /* 5 */
189 RET_LBL(stg_seq_frame), /* 6 */
190 RET_LBL(stg_seq_frame) /* 7 */
194 jump %ENTRY_CODE(Sp(0));