https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99217
--- Comment #5 from huangpei at loongson dot cn <huangpei at loongson dot cn>
---
Hi, with this fix and bug 93242 fixed, a.c with mips16 is OK,
ambrosehua@3A1000-800M:~$ gcc -fpatchable-function-entry=3 -mips16 -mabi=32
-c a.c -S -o a.1.s
ambrosehua@3A1000-800M:~$ cat a.1.s
.file 1 "a.c"
.section .mdebug.abi32
.previous
.nan legacy
.module fp=xx
.module nooddspreg
.abicalls
.text
.align 2
.globl f
.set mips16
.set nomicromips
.ent f
.type f, @function
f:
.section __patchable_function_entries,"a",@progbits
.4byte $LPFE1
.text
$LPFE1:
.set noreorder
nop
.set reorder
.set noreorder
nop
.set reorder
.set noreorder
nop
.set reorder
.frame $17,8,$31 # vars= 0, regs= 1/0, args= 0, gp= 0
.mask 0x00020000,-4
.fmask 0x00000000,0
save 8,$17
move $17,$sp
.set noreorder
nop
.set reorder
move $sp,$17
restore 8,$17
jr $31
.end f
.size f, .-f
.ident "GCC: (Debian 8.3.0-8.lnd.4) 8.3.0"
ambrosehua@3A1000-800M:~$ objdump -tdr a.1.o
a.1.o: file format elf32-tradlittlemips
SYMBOL TABLE:
00000000 l df *ABS* 00000000 a.c
00000000 l d .text 00000000 .text
00000000 l d .data 00000000 .data
00000000 l d .bss 00000000 .bss
00000000 l d .mdebug.abi32 00000000 .mdebug.abi32
00000000 l d __patchable_function_entries 00000000
__patchable_function_entries
00000000 l .text 00000000 0xf0 $LPFE1
00000000 l d .reginfo 00000000 .reginfo
00000000 l d .MIPS.abiflags 00000000 .MIPS.abiflags
00000000 l d .pdr 00000000 .pdr
00000000 l d .comment 00000000 .comment
00000000 l d .gnu.attributes 00000000 .gnu.attributes
00000000 g F .text 00000012 f
Disassembly of section .text:
00000000 <f>:
0: 6500 nop
2: 6500 nop
4: 6500 nop
6: 6491 save 8,s1
8: 673d move s1,sp
a: 6500 nop
c: 65b9 move sp,s1
e: 6411 restore 8,s1
10: e8a0 jrc ra
12: 6500 nop
14: 6500 nop
16: 6500 nop
18: 6500 nop
1a: 6500 nop
1c: 6500 nop
1e: 6500 nop
but， with b.c,
ambrosehua@3A1000-800M:~$ cat b.c
void f(float a, float b)
{
}
it is much more complicated.
ambrosehua@3A1000-800M:~$ gcc -fpatchable-function-entry=3 -mips16 -mabi=32
-c b.c -S -o b.1.s
ambrosehua@3A1000-800M:~$ cat b.1.s
.section .mdebug.abi32
.previous
.nan legacy
.module fp=xx
.module nooddspreg
.abicalls
.text
.align 2
.globl f
.set mips16
.set nomicromips
.ent f
.type f, @function
f:
.section __patchable_function_entries,"a",@progbits
.4byte $LPFE1
.text
$LPFE1:
.set noreorder
nop
.set reorder
.set noreorder
nop
.set reorder
.set noreorder
nop
.set reorder
# Stub function for f (float, float)
.section .mips16.fn.f,"ax",@progbits
.align 2
.set mips16
.set nomicromips
.ent __fn_stub_f
.type __fn_stub_f, @function
__fn_stub_f:
.section __patchable_function_entries
.4byte $LPFE2
.section .mips16.fn.f
$LPFE2:
.set noreorder
nop
.set reorder
.set noreorder
nop
.set reorder
.set noreorder
nop
.set reorder
.set nomips16
.set nomicromips
.ent __fn_stub_f
.type __fn_stub_f, @function
__fn_stub_f:
.set noreorder
.cpload $25
.set reorder
.reloc 0,R_MIPS_NONE,f
la $25,__fn_local_f
mfc1 $4,$f12
mfc1 $5,$f14
jr $25
.end __fn_stub_f
__fn_local_f = f
.text
.frame $17,8,$31 # vars= 0, regs= 1/0, args= 0, gp= 0
.mask 0x00020000,-4
.fmask 0x00000000,0
save 8,$17
move $17,$sp
sw $4,8($17)
sw $5,12($17)
.set noreorder
nop
.set reorder
move $sp,$17
restore 8,$17
jr $31
.end f
.size f, .-f
.ident "GCC: (Debian 8.3.0-8.lnd.4) 8.3.0"
for comparison， without -fpatchable-function-entry=3
ambrosehua@3A1000-800M:~$ gcc -mips16 -mabi=32 -c b.c -S -o b.2.s
ambrosehua@3A1000-800M:~$ cat b.2.s
.file 1 "b.c"
.section .mdebug.abi32
.previous
.nan legacy
.module fp=xx
.module nooddspreg
.abicalls
.text
.align 2
.globl f
.set mips16
.set nomicromips
.ent f
.type f, @function
f:
# Stub function for f (float, float)
.section .mips16.fn.f,"ax",@progbits
.align 2
.set mips16
.set nomicromips
.ent __fn_stub_f
.type __fn_stub_f, @function
__fn_stub_f:
.set nomips16
.set nomicromips
.ent __fn_stub_f
.type __fn_stub_f, @function
__fn_stub_f:
.set noreorder
.cpload $25
.set reorder
.reloc 0,R_MIPS_NONE,f
la $25,__fn_local_f
mfc1 $4,$f12
mfc1 $5,$f14
jr $25
.end __fn_stub_f
__fn_local_f = f
.text
.frame $17,8,$31 # vars= 0, regs= 1/0, args= 0, gp= 0
.mask 0x00020000,-4
.fmask 0x00000000,0
save 8,$17
move $17,$sp
sw $4,8($17)
sw $5,12($17)
.set noreorder
nop
.set reorder
move $sp,$17
restore 8,$17
jr $31
.end f
.size f, .-f
.ident "GCC: (Debian 8.3.0-8.lnd.4) 8.3.0"
with original gcc 8.3 in Debian10,
depaulose@3A1000-800M:/home/ambrosehua$ gcc -mabi=32 -c b.c -S -o b.3.s
-mips16
depaulose@3A1000-800M:/home/ambrosehua$ cat b.3.s
.file 1 "b.c"
.section .mdebug.abi32
.previous
.nan legacy
.module fp=xx
.module nooddspreg
.abicalls
.text
.align 2
.globl f
# Stub function for f (float, float)
.section .mips16.fn.f,"ax",@progbits
.align 2
.set nomips16
.set nomicromips
.ent __fn_stub_f
.type __fn_stub_f, @function
__fn_stub_f:
.set noreorder
.cpload $25
.set reorder
.reloc 0,R_MIPS_NONE,f
la $25,__fn_local_f
mfc1 $4,$f12
mfc1 $5,$f14
jr $25
.end __fn_stub_f
__fn_local_f = f
.text
.set mips16
.set nomicromips
.ent f
.type f, @function
f:
.frame $17,8,$31 # vars= 0, regs= 1/0, args= 0, gp= 0
.mask 0x00020000,-4
.fmask 0x00000000,0
save 8,$17
move $17,$sp
sw $4,8($17)
sw $5,12($17)
.set noreorder
nop
.set reorder
move $sp,$17
restore 8,$17
jr $31
.end f
.size f, .-f
.ident "GCC: (Debian 8.3.0-6) 8.3.0"
I think there is somthing wrong here with handling stub for O32 MIPS16 floating
parameter.
+. Point 1, with b.3.s, the func entry should be __fn_stub_f instead of f,
which I mean the f in symbol table should point to the __fn_stub_f in the b.3.s
, and __fn_local_f in symbol table should point to the f in the b.3.s ;
+. Point 2, if Point 1 is right, the b.2.s should be just like Point 1, but it
is not right now, and we need fix this at first;
+. Point 3, if Point 1 is right, b.1.s should has only 3 nops in the mip32 32
stub code, instead of both in mips32 stub code and mip16 code.
Did I get it right?
