https://llvm.org/bugs/show_bug.cgi?id=25028
Bug ID: 25028
Summary: [mips64] Incorrect dwarf info
Product: new-bugs
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: new bugs
Assignee: unassignedb...@nondot.org
Reporter: d...@codeplay.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
Created attachment 14983
--> https://llvm.org/bugs/attachment.cgi?id=14983&action=edit
Bitcode
Hi,
I have got a case where the mips64el compiler creates incorrect dwarf info, as
far as I can understand. The bitcode is originally generated from an Android
RenderScript source file, attached for reference. It contains two functions
(test1 and test2), both marked with the attribute no-frame-pointer-elim, which
should keep the usage of the register $fp (r30). I am building the final object
with:
llc -relocation-model=pic -filetype=obj -mtriple=mips64el-none-linux-android -o
dummy.o dummy.bc
Looking into the generated assembler for the function test2:
test2:
98: 60 fd bd 67 daddiu $sp, $sp, -672
9c: 98 02 bf ff sd $ra, 664($sp)
a0: 90 02 be ff sd $fp, 656($sp)
a4: 88 02 bc ff sd $gp, 648($sp)
a8: 80 02 b7 ff sd $23, 640($sp)
ac: 78 02 b6 ff sd $22, 632($sp)
b0: 70 02 b5 ff sd $21, 624($sp)
b4: 68 02 b4 ff sd $20, 616($sp)
b8: 60 02 b3 ff sd $19, 608($sp)
bc: 58 02 b2 ff sd $18, 600($sp)
c0: 50 02 b1 ff sd $17, 592($sp)
c4: 48 02 b0 ff sd $16, 584($sp)
c8: 25 f0 a0 03 move $fp, $sp
cc: e0 ff 1c 64 daddiu $gp, $zero, -32
d0: 24 e8 bc 03 and $sp, $sp, $gp
d4: 00 08 04 00 sll $1, $4, 0
d8: 44 02 a1 af sw $1, 580($sp)
dc: 44 02 a1 93 lbu $1, 580($sp)
e0: 45 02 a2 93 lbu $2, 581($sp)
e4: 46 02 a3 93 lbu $3, 582($sp)
e8: 47 02 a4 93 lbu $4, 583($sp)
ec: 43 02 a4 a3 sb $4, 579($sp)
f0: 42 02 a3 a3 sb $3, 578($sp)
f4: 41 02 a2 a3 sb $2, 577($sp)
f8: 40 02 a1 a3 sb $1, 576($sp)
fc: 01 00 01 64 daddiu $1, $zero, 1
100: 3c 0c 01 00 dsll32 $1, $1, 16
104: 18 00 02 3c lui $2, 24
108: 02 00 03 3c lui $3, 2
10c: 03 00 04 3c lui $4, 3
110: 61 00 05 24 addiu $5, $zero, 97
114: 3c 02 a5 a3 sb $5, 572($sp)
...
The address 110 in .text should correspond to the assignment in the source file
char_local = 'a';. Its value is subsequently stored at the position $sp + 572 .
Note that the $fp and $sp match at the address c8, however the $sp is further
moved at the address d0, potentially implying $sp != $fp hereafter.
Looking at the dwarf info, it says that the base address for the function test2
is the $fp:
<1><46>: Abbrev Number: 3 (DW_TAG_subprogram)
<47> DW_AT_low_pc : 0x0
<4f> DW_AT_high_pc : 0x94
<53> DW_AT_frame_base : 1 byte block: 6e (DW_OP_reg30 (r30))
<55> DW_AT_name : (indirect string, offset: 0xc6): test1
<59> DW_AT_decl_file : 1
<5a> DW_AT_decl_line : 5
<5b> DW_AT_prototyped : 1
<5b> DW_AT_type : <0x36d>
<5f> DW_AT_external : 1
and that the local variable char_local is at $fp + 572:
<2><c0>: Abbrev Number: 5 (DW_TAG_variable)
<c1> DW_AT_location : 3 byte block: 91 bc 4 (DW_OP_fbreg: 572)
<c5> DW_AT_name : (indirect string, offset: 0x111): char_local
<c9> DW_AT_decl_file : 1
<ca> DW_AT_decl_line : 17
<cb> DW_AT_type : <0x2a>
which is wrong as the $fp != $sp.
Tested with the tip of LLVM.
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