compiler-rt/lib/builtins/hexagon/common_entry_exit_legacy.S

   1 //===----------------------Hexagon builtin routine ------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9
  10 // Functions that implement common sequences in function prologues and epilogues
  11 // used to save code size
  12
  13         .macro FUNCTION_BEGIN name
  14         .text
  15         .globl \name
  16         .type  \name, @function
  17         .falign
  18 \name:
  19         .endm
  20
  21         .macro FUNCTION_END name
  22         .size  \name, . - \name
  23         .endm
  24
  25         .macro FALLTHROUGH_TAIL_CALL name0 name1
  26         .size \name0, . - \name0
  27         .globl \name1
  28         .type \name1, @function
  29         .falign
  30 \name1:
  31         .endm
  32
  33
  34
  35
  36 // Save r27:26 at fp+#-8, r25:24 at fp+#-16, r23:22 at fp+#-24, r21:20 at
  37 // fp+#-32, r19:18 at fp+#-40, and r17:16 at fp+#-48.
  38
  39
  40
  41
  42 // The compiler knows that the __save_* functions clobber LR.  No other
  43 // registers should be used without informing the compiler.
  44
  45 // Since we can only issue one store per packet, we don't hurt performance by
  46 // simply jumping to the right point in this sequence of stores.
  47
  48 FUNCTION_BEGIN __save_r27_through_r16
  49                 memd(fp+#-48) = r17:16
  50 FALLTHROUGH_TAIL_CALL __save_r27_through_r16 __save_r27_through_r18
  51                 memd(fp+#-40) = r19:18
  52 FALLTHROUGH_TAIL_CALL __save_r27_through_r18 __save_r27_through_r20
  53                 memd(fp+#-32) = r21:20
  54 FALLTHROUGH_TAIL_CALL __save_r27_through_r20 __save_r27_through_r22
  55                 memd(fp+#-24) = r23:22
  56 FALLTHROUGH_TAIL_CALL __save_r27_through_r22 __save_r27_through_r24
  57                 memd(fp+#-16) = r25:24
  58         {
  59                 memd(fp+#-8) = r27:26
  60                 jumpr lr
  61         }
  62 FUNCTION_END __save_r27_through_r24
  63
  64
  65
  66
  67 // For each of the *_before_sibcall functions, jumpr lr is executed in parallel
  68 // with deallocframe.  That way, the return gets the old value of lr, which is
  69 // where these functions need to return, and at the same time, lr gets the value
  70 // it needs going into the sibcall.
  71
  72 FUNCTION_BEGIN __restore_r27_through_r20_and_deallocframe_before_sibcall
  73         {
  74                 r21:20 = memd(fp+#-32)
  75                 r23:22 = memd(fp+#-24)
  76         }
  77 FALLTHROUGH_TAIL_CALL __restore_r27_through_r20_and_deallocframe_before_sibcall __restore_r27_through_r24_and_deallocframe_before_sibcall
  78         {
  79                 r25:24 = memd(fp+#-16)
  80                 jump __restore_r27_through_r26_and_deallocframe_before_sibcall
  81         }
  82 FUNCTION_END __restore_r27_through_r24_and_deallocframe_before_sibcall
  83
  84
  85
  86
  87 FUNCTION_BEGIN __restore_r27_through_r16_and_deallocframe_before_sibcall
  88                 r17:16 = memd(fp+#-48)
  89 FALLTHROUGH_TAIL_CALL __restore_r27_through_r16_and_deallocframe_before_sibcall __restore_r27_through_r18_and_deallocframe_before_sibcall
  90         {
  91                 r19:18 = memd(fp+#-40)
  92                 r21:20 = memd(fp+#-32)
  93         }
  94 FALLTHROUGH_TAIL_CALL __restore_r27_through_r18_and_deallocframe_before_sibcall __restore_r27_through_r22_and_deallocframe_before_sibcall
  95         {
  96                 r23:22 = memd(fp+#-24)
  97                 r25:24 = memd(fp+#-16)
  98         }
  99 FALLTHROUGH_TAIL_CALL __restore_r27_through_r22_and_deallocframe_before_sibcall __restore_r27_through_r26_and_deallocframe_before_sibcall
 100         {
 101                 r27:26 = memd(fp+#-8)
 102                 deallocframe
 103                 jumpr lr
 104         }
 105 FUNCTION_END __restore_r27_through_r26_and_deallocframe_before_sibcall
 106
 107
 108
 109
 110 // Here we use the extra load bandwidth to restore LR early, allowing the return
 111 // to occur in parallel with the deallocframe.
 112
 113 FUNCTION_BEGIN __restore_r27_through_r16_and_deallocframe
 114         {
 115                 r17:16 = memd(fp+#-48)
 116                 r19:18 = memd(fp+#-40)
 117         }
 118 FALLTHROUGH_TAIL_CALL __restore_r27_through_r16_and_deallocframe __restore_r27_through_r20_and_deallocframe
 119         {
 120                 r21:20 = memd(fp+#-32)
 121                 r23:22 = memd(fp+#-24)
 122         }
 123 FALLTHROUGH_TAIL_CALL __restore_r27_through_r20_and_deallocframe __restore_r27_through_r24_and_deallocframe
 124         {
 125                 lr = memw(fp+#4)
 126                 r25:24 = memd(fp+#-16)
 127         }
 128         {
 129                 r27:26 = memd(fp+#-8)
 130                 deallocframe
 131                 jumpr lr
 132         }
 133 FUNCTION_END __restore_r27_through_r24_and_deallocframe
 134
 135
 136
 137
 138 // Here the load bandwidth is maximized for all three functions.
 139
 140 FUNCTION_BEGIN __restore_r27_through_r18_and_deallocframe
 141         {
 142                 r19:18 = memd(fp+#-40)
 143                 r21:20 = memd(fp+#-32)
 144         }
 145 FALLTHROUGH_TAIL_CALL __restore_r27_through_r18_and_deallocframe __restore_r27_through_r22_and_deallocframe
 146         {
 147                 r23:22 = memd(fp+#-24)
 148                 r25:24 = memd(fp+#-16)
 149         }
 150 FALLTHROUGH_TAIL_CALL __restore_r27_through_r22_and_deallocframe __restore_r27_through_r26_and_deallocframe
 151         {
 152                 r27:26 = memd(fp+#-8)
 153                 deallocframe
 154         }
 155                 jumpr lr
 156 FUNCTION_END __restore_r27_through_r26_and_deallocframe