[RISCV][compiler-rt] Add CFI directives to save-restore implementation

[edward-jones]

Summary

This adds CFI directives to compiler-rt's version of the -msave-restore runtime functions. This means it is possible to debug other frames even when execution is stopped in these functions.

[luismarques]

LGTM

compiler-rt/lib/builtins/riscv/restore.S

// alignment.
 
   .text
 
 #if __riscv_xlen == 32
 
   .globl  __riscv_restore_12
   .type   __riscv_restore_12,@function
 __riscv_restore_12:
+  .cfi_startproc
+  .cfi_def_cfa_offset 64
+  .cfi_offset s11, -64+12
+  .cfi_offset s10, -64+16
+  .cfi_offset s9, -64+20
+  .cfi_offset s8, -64+24
+  .cfi_offset s7, -64+28
+  .cfi_offset s6, -64+32
+  .cfi_offset s5, -64+36
+  .cfi_offset s4, -64+40
+  .cfi_offset s3, -64+44
+  .cfi_offset s2, -64+48
+  .cfi_offset s1, -64+52
+  .cfi_offset s0, -64+56
+  .cfi_offset ra, -64+60
   lw      s11, 12(sp)
+  .cfi_restore s11
   addi    sp, sp, 16
   // fallthrough into __riscv_restore_11/10/9/8
 
   .globl  __riscv_restore_11
   .type   __riscv_restore_11,@function
   .globl  __riscv_restore_10
   .type   __riscv_restore_10,@function
   .globl  __riscv_restore_9
   .type   __riscv_restore_9,@function
   .globl  __riscv_restore_8
   .type   __riscv_restore_8,@function
 __riscv_restore_11:
 __riscv_restore_10:
 __riscv_restore_9:
 __riscv_restore_8:
+  .cfi_restore s11
+  .cfi_def_cfa_offset 48
   lw      s10, 0(sp)
+  .cfi_restore s10
   lw      s9,  4(sp)
+  .cfi_restore s9
   lw      s8,  8(sp)
+  .cfi_restore s8
   lw      s7,  12(sp)
+  .cfi_restore s7
   addi    sp, sp, 16
   // fallthrough into __riscv_restore_7/6/5/4
 
   .globl  __riscv_restore_7
   .type   __riscv_restore_7,@function
   .globl  __riscv_restore_6
   .type   __riscv_restore_6,@function
   .globl  __riscv_restore_5
   .type   __riscv_restore_5,@function
   .globl  __riscv_restore_4
   .type   __riscv_restore_4,@function
 __riscv_restore_7:
 __riscv_restore_6:
 __riscv_restore_5:
 __riscv_restore_4:
+  .cfi_restore s7
+  .cfi_restore s8
+  .cfi_restore s9
+  .cfi_restore s10
+  .cfi_restore s11
+  .cfi_def_cfa_offset 32
   lw      s6,  0(sp)
+  .cfi_restore s6
   lw      s5,  4(sp)
+  .cfi_restore s5
   lw      s4,  8(sp)
+  .cfi_restore s4
   lw      s3,  12(sp)
+  .cfi_restore s3
   addi    sp, sp, 16
   // fallthrough into __riscv_restore_3/2/1/0
 
   .globl  __riscv_restore_3
   .type   __riscv_restore_3,@function
   .globl  __riscv_restore_2
   .type   __riscv_restore_2,@function
   .globl  __riscv_restore_1
   .type   __riscv_restore_1,@function
   .globl  __riscv_restore_0
   .type   __riscv_restore_0,@function
 __riscv_restore_3:
 __riscv_restore_2:
 __riscv_restore_1:
 __riscv_restore_0:
+  .cfi_restore s3
+  .cfi_restore s4
+  .cfi_restore s5
+  .cfi_restore s6
+  .cfi_restore s7
+  .cfi_restore s8
+  .cfi_restore s9
+  .cfi_restore s10
+  .cfi_restore s11
+  .cfi_def_cfa_offset 16
   lw      s2,  0(sp)
+  .cfi_restore s2
   lw      s1,  4(sp)
+  .cfi_restore s1
   lw      s0,  8(sp)
+  .cfi_restore s0
   lw      ra,  12(sp)
+  .cfi_restore ra
   addi    sp, sp, 16
+  .cfi_def_cfa_offset 0
   ret
+  .cfi_endproc
 
 #elif __riscv_xlen == 64
 
   .globl  __riscv_restore_12
   .type   __riscv_restore_12,@function
 __riscv_restore_12:
+  .cfi_startproc
+  .cfi_def_cfa_offset 112
+  .cfi_offset s11, -112+8
+  .cfi_offset s10, -112+16
+  .cfi_offset s9, -112+24
+  .cfi_offset s8, -112+32
+  .cfi_offset s7, -112+40
+  .cfi_offset s6, -112+48
+  .cfi_offset s5, -112+56
+  .cfi_offset s4, -112+64
+  .cfi_offset s3, -112+72
+  .cfi_offset s2, -112+80
+  .cfi_offset s1, -112+88
+  .cfi_offset s0, -112+96
+  .cfi_offset ra, -112+104
   ld      s11, 8(sp)
+  .cfi_restore s11
   addi    sp, sp, 16
   // fallthrough into __riscv_restore_11/10
 
   .globl  __riscv_restore_11
   .type   __riscv_restore_11,@function
   .globl  __riscv_restore_10
   .type   __riscv_restore_10,@function
 __riscv_restore_11:
 __riscv_restore_10:
+  .cfi_restore s11
+  .cfi_def_cfa_offset 96
   ld      s10, 0(sp)
+  .cfi_restore s10
   ld      s9,  8(sp)
+  .cfi_restore s9
   addi    sp, sp, 16
   // fallthrough into __riscv_restore_9/8
 
   .globl  __riscv_restore_9
   .type   __riscv_restore_9,@function
   .globl  __riscv_restore_8
   .type   __riscv_restore_8,@function
 __riscv_restore_9:
 __riscv_restore_8:
+  .cfi_restore s9
+  .cfi_restore s10
+  .cfi_restore s11
+  .cfi_def_cfa_offset 80
   ld      s8,  0(sp)
+  .cfi_restore s8
   ld      s7,  8(sp)
+  .cfi_restore s7
   addi    sp, sp, 16
   // fallthrough into __riscv_restore_7/6
 
   .globl  __riscv_restore_7
   .type   __riscv_restore_7,@function
   .globl  __riscv_restore_6
   .type   __riscv_restore_6,@function
 __riscv_restore_7:
 __riscv_restore_6:
+  .cfi_restore s7
+  .cfi_restore s8
+  .cfi_restore s9
+  .cfi_restore s10
+  .cfi_restore s11
+  .cfi_def_cfa_offset 64
   ld      s6,  0(sp)
+  .cfi_restore s6
   ld      s5,  8(sp)
+  .cfi_restore s5
   addi    sp, sp, 16
   // fallthrough into __riscv_restore_5/4
 
   .globl  __riscv_restore_5
   .type   __riscv_restore_5,@function
   .globl  __riscv_restore_4
   .type   __riscv_restore_4,@function
 __riscv_restore_5:
 __riscv_restore_4:
+  .cfi_restore s5
+  .cfi_restore s6
+  .cfi_restore s7
+  .cfi_restore s8
+  .cfi_restore s9
+  .cfi_restore s10
+  .cfi_restore s11
+  .cfi_def_cfa_offset 48
   ld      s4,  0(sp)
+  .cfi_restore s4
   ld      s3,  8(sp)
+  .cfi_restore s3
   addi    sp, sp, 16
   // fallthrough into __riscv_restore_3/2
 
   .globl  __riscv_restore_3
   .type   __riscv_restore_3,@function
   .globl  __riscv_restore_2
   .type   __riscv_restore_2,@function
 __riscv_restore_3:
 __riscv_restore_2:
+  .cfi_restore s3
+  .cfi_restore s4
+  .cfi_restore s5
+  .cfi_restore s6
+  .cfi_restore s7
+  .cfi_restore s8
+  .cfi_restore s9
+  .cfi_restore s10
+  .cfi_restore s11
+  .cfi_def_cfa_offset 32
   ld      s2,  0(sp)
+  .cfi_restore s2
   ld      s1,  8(sp)
+  .cfi_restore s1
   addi    sp, sp, 16
   // fallthrough into __riscv_restore_1/0
 
   .globl  __riscv_restore_1
   .type   __riscv_restore_1,@function
   .globl  __riscv_restore_0
   .type   __riscv_restore_0,@function
 __riscv_restore_1:
 __riscv_restore_0:
+  .cfi_restore s1
+  .cfi_restore s2
+  .cfi_restore s3
+  .cfi_restore s4
+  .cfi_restore s5
+  .cfi_restore s6
+  .cfi_restore s7
+  .cfi_restore s8
+  .cfi_restore s9
+  .cfi_restore s10
+  .cfi_restore s11
+  .cfi_def_cfa_offset 16
   ld      s0,  0(sp)
+  .cfi_restore s0
   ld      ra,  8(sp)
+  .cfi_restore ra
   addi    sp, sp, 16
+  .cfi_def_cfa_offset 0
   ret
+  .cfi_endproc
 
 #else
 # error "xlen must be 32 or 64 for save-restore implementation
 #endif

compiler-rt/lib/builtins/riscv/save.S

// alignment.
 
   .text
 
 #if __riscv_xlen == 32
 
   .globl  __riscv_save_12
   .type   __riscv_save_12,@function
 __riscv_save_12:
+  .cfi_startproc
+  .cfi_return_column t0  # return through t0 not ra
   addi   sp, sp, -64
+  .cfi_def_cfa_offset 64
   mv     t1, zero
   sw     s11, 12(sp)
+  .cfi_offset s11, -64+12
   j      .Lriscv_save_11_8
 
   .globl  __riscv_save_11
   .type   __riscv_save_11,@function
   .globl  __riscv_save_10
   .type   __riscv_save_10,@function
   .globl  __riscv_save_9
   .type   __riscv_save_9,@function
   .globl  __riscv_save_8
   .type   __riscv_save_8,@function
 __riscv_save_11:
 __riscv_save_10:
 __riscv_save_9:
 __riscv_save_8:
+  .cfi_restore s11
   addi   sp, sp, -64
+  .cfi_def_cfa_offset 64
   li     t1, 16
 .Lriscv_save_11_8:
   sw     s10, 16(sp)
+  .cfi_offset s10, -64+16
   sw     s9,  20(sp)
+  .cfi_offset s9, -64+20
   sw     s8,  24(sp)
+  .cfi_offset s8, -64+24
   sw     s7,  28(sp)
+  .cfi_offset s7, -64+28
   j      .Lriscv_save_7_4
 
   .globl  __riscv_save_7
   .type   __riscv_save_7,@function
   .globl  __riscv_save_6
   .type   __riscv_save_6,@function
   .globl  __riscv_save_5
   .type   __riscv_save_5,@function
   .globl  __riscv_save_4
   .type   __riscv_save_4,@function
 __riscv_save_7:
 __riscv_save_6:
 __riscv_save_5:
 __riscv_save_4:
+  .cfi_restore s7
+  .cfi_restore s8
+  .cfi_restore s9
+  .cfi_restore s10
+  .cfi_restore s11
   addi   sp, sp, -64
+  .cfi_def_cfa_offset 64
   li     t1, 32
 .Lriscv_save_7_4:
   sw     s6, 32(sp)
+  .cfi_offset s6, -64+32
   sw     s5, 36(sp)
+  .cfi_offset s5, -64+36
   sw     s4, 40(sp)
+  .cfi_offset s4, -64+40
   sw     s3, 44(sp)
+  .cfi_offset s3, -64+44
   sw     s2, 48(sp)
+  .cfi_offset s2, -64+48
   sw     s1, 52(sp)
+  .cfi_offset s1, -64+52
   sw     s0, 56(sp)
+  .cfi_offset s0, -64+56
   sw     ra, 60(sp)
+  .cfi_offset ra, -64+60
   add    sp, sp, t1
   jr     t0
+  .cfi_endproc
 
   .globl  __riscv_save_3
   .type   __riscv_save_3,@function
   .globl  __riscv_save_2
   .type   __riscv_save_2,@function
   .globl  __riscv_save_1
   .type   __riscv_save_1,@function
   .globl  __riscv_save_0
   .type   __riscv_save_0,@function
 __riscv_save_3:
 __riscv_save_2:
 __riscv_save_1:
 __riscv_save_0:
+  .cfi_startproc
+  .cfi_return_column t0  # return through t0 not ra
   addi    sp, sp, -16
+  .cfi_def_cfa_offset 16
   sw      s2,  0(sp)
+  .cfi_offset s2, -16+0
   sw      s1,  4(sp)
+  .cfi_offset s1, -16+4
   sw      s0,  8(sp)
+  .cfi_offset s0, -16+8
   sw      ra,  12(sp)
+  .cfi_offset ra, -16+12
   jr      t0
+  .cfi_endproc
 
 #elif __riscv_xlen == 64
 
   .globl  __riscv_save_12
   .type   __riscv_save_12,@function
 __riscv_save_12:
+  .cfi_startproc
+  .cfi_return_column t0  # return through t0 not ra
   addi   sp, sp, -112
+  .cfi_def_cfa_offset 112
   mv     t1, zero
   sd     s11, 8(sp)
+  .cfi_offset s11, -112+8
   j      .Lriscv_save_11_10
 
   .globl  __riscv_save_11
   .type   __riscv_save_11,@function
   .globl  __riscv_save_10
   .type   __riscv_save_10,@function
 __riscv_save_11:
 __riscv_save_10:
+  .cfi_restore s11
   addi   sp, sp, -112
+  .cfi_def_cfa_offset 112
   li     t1, 16
 .Lriscv_save_11_10:
   sd     s10, 16(sp)
+  .cfi_offset s10, -112+16
   sd     s9,  24(sp)
+  .cfi_offset s9, -112+24
   j      .Lriscv_save_9_8
 
   .globl  __riscv_save_9
   .type   __riscv_save_9,@function
   .globl  __riscv_save_8
   .type   __riscv_save_8,@function
 __riscv_save_9:
 __riscv_save_8:
+  .cfi_restore s9
+  .cfi_restore s10
+  .cfi_restore s11
   addi   sp, sp, -112
+  .cfi_def_cfa_offset 112
   li     t1, 32
 .Lriscv_save_9_8:
   sd     s8,  32(sp)
+  .cfi_offset s8, -112+32
   sd     s7,  40(sp)
+  .cfi_offset s7, -112+40
   j      .Lriscv_save_7_6
 
   .globl  __riscv_save_7
   .type   __riscv_save_7,@function
   .globl  __riscv_save_6
   .type   __riscv_save_6,@function
 __riscv_save_7:
 __riscv_save_6:
+  .cfi_restore s7
+  .cfi_restore s8
+  .cfi_restore s9
+  .cfi_restore s10
+  .cfi_restore s11
   addi   sp, sp, -112
+  .cfi_def_cfa_offset 112
   li     t1, 48
 .Lriscv_save_7_6:
   sd     s6,  48(sp)
+  .cfi_offset s6, -112+48
   sd     s5,  56(sp)
+  .cfi_offset s5, -112+56
   j      .Lriscv_save_5_4
 
   .globl  __riscv_save_5
   .type   __riscv_save_5,@function
   .globl  __riscv_save_4
   .type   __riscv_save_4,@function
 __riscv_save_5:
 __riscv_save_4:
+  .cfi_restore s5
+  .cfi_restore s6
+  .cfi_restore s7
+  .cfi_restore s8
+  .cfi_restore s9
+  .cfi_restore s10
+  .cfi_restore s11
   addi   sp, sp, -112
+  .cfi_def_cfa_offset 112
   li     t1, 64
 .Lriscv_save_5_4:
   sd     s4, 64(sp)
+  .cfi_offset s4, -112+64
   sd     s3, 72(sp)
+  .cfi_offset s3, -112+72
   j      .Lriscv_save_3_2
 
   .globl  __riscv_save_3
   .type   __riscv_save_3,@function
   .globl  __riscv_save_2
   .type   __riscv_save_2,@function
 __riscv_save_3:
 __riscv_save_2:
+  .cfi_restore s3
+  .cfi_restore s4
+  .cfi_restore s5
+  .cfi_restore s6
+  .cfi_restore s7
+  .cfi_restore s8
+  .cfi_restore s9
+  .cfi_restore s10
+  .cfi_restore s11
   addi   sp, sp, -112
+  .cfi_def_cfa_offset 112
   li     t1, 80
 .Lriscv_save_3_2:
   sd     s2, 80(sp)
+  .cfi_offset s2, -112+80
   sd     s1, 88(sp)
+  .cfi_offset s1, -112+88
   sd     s0, 96(sp)
+  .cfi_offset s0, -112+96
   sd     ra, 104(sp)
+  .cfi_offset ra, -112+104
   add    sp, sp, t1
   jr     t0
+  .cfi_endproc
 
   .globl  __riscv_save_1
   .type   __riscv_save_1,@function
   .globl  __riscv_save_0
   .type   __riscv_save_0,@function
 __riscv_save_1:
 __riscv_save_0:
+  .cfi_startproc
+  .cfi_return_column t0  # return through t0 not ra
   addi   sp, sp, -16
+  .cfi_def_cfa_offset 16
   sd     s0, 0(sp)
+  .cfi_offset s0, -16+0
   sd     ra, 8(sp)
+  .cfi_offset ra, -16+8
   jr     t0
+  .cfi_endproc
 
 #else
 # error "xlen must be 32 or 64 for save-restore implementation
 #endif