* What's wrong with this RTL?
@ 2022-01-10 4:48 Andras Tantos
2022-01-10 6:19 ` Andrew Pinski
0 siblings, 1 reply; 3+ messages in thread
From: Andras Tantos @ 2022-01-10 4:48 UTC (permalink / raw)
To: gcc
All!
I'm trying to port GCC to a new target, I call 'brew'. I've based it on
the Moxie target mostly because of it's simplicity.
I must be doing something horribly wrong as the following C code crokes
in the LRA path:
long long foo (long long a, long long *w)
{
return __builtin_add_overflow (a, a, w);
}
The error message I get is the following:
during RTL pass: reload
../brew-gcc-build/second.c: In function ‘foo’:
../brew-gcc-build/second.c:5:1: internal compiler error: maximum
number of generated reload insns per insn achieved (90)
5 | }
| ^
0xd23854 lra_constraints(bool)
../../brew-gcc/gcc/lra-constraints.c:5095
0xd10322 lra(_IO_FILE*)
../../brew-gcc/gcc/lra.c:2336
0xcc86d9 do_reload
../../brew-gcc/gcc/ira.c:5932
0xcc86d9 execute
../../brew-gcc/gcc/ira.c:6118
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
The repro seems to go away, if:
1. If I don't use the return value from __builtin_add_overflow
2. If I don't return a long long value
3. If I use some other function, which is not inlined
4. If I write and call some other (somewhat non-trivial) force-inline
function myself
In other words, this is pretty much the minimal repro, I've found so
far.
The initial RTL passed in to LRA appears to be:
(insn 2 4 3 2 (set (mem/f/c:SI (plus:SI (reg/f:SI 16 ?ap)
(const_int 12 [0xc])) [2 w+0 S4 A32])
(reg:SI 4 $r4)) "../brew-gcc-build/second.c":2:1 23
{*movsi_store}
(expr_list:REG_DEAD (reg:SI 4 $r4)
(nil)))
(note 3 2 8 2 NOTE_INSN_FUNCTION_BEG)
(insn 8 3 6 2 (clobber (reg:DI 27 [ _5+8 ])) "../brew-gcc-
build/second.c":3:10 -1
(nil))
(insn 6 8 7 2 (set (subreg:SI (reg:DI 27 [ _5+8 ]) 0)
(const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
{*movsi_immed}
(nil))
(insn 7 6 13 2 (set (subreg:SI (reg:DI 27 [ _5+8 ]) 4)
(const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
{*movsi_immed}
(nil))
(insn 13 7 18 2 (clobber (reg:DI 30)) "../brew-gcc-
build/second.c":3:10 -1
(nil))
(insn 18 13 19 2 (clobber (reg:DI 33)) "../brew-gcc-
build/second.c":3:10 -1
(nil))
(insn 19 18 20 2 (clobber (reg:DI 36)) "../brew-gcc-
build/second.c":3:10 -1
(nil))
(insn 20 19 21 2 (set (subreg:SI (reg:DI 36) 4)
(plus:SI (subreg:SI (reg:DI 30) 4)
(subreg:SI (reg:DI 33) 4))) "../brew-gcc-
build/second.c":3:10 2 {addsi3}
(nil))
(insn 21 20 22 2 (set (reg:SI 37)
(const_int 1 [0x1])) "../brew-gcc-build/second.c":3:10 20
{*movsi_immed}
(nil))
(jump_insn 22 21 83 2 (set (pc)
(if_then_else (ltu (subreg:SI (reg:DI 36) 4)
(subreg:SI (reg:DI 30) 4))
(label_ref 24)
(pc))) "../brew-gcc-build/second.c":3:10 38 {cbranchsi4}
(nil)
-> 24)
(note 83 22 23 3 [bb 3] NOTE_INSN_BASIC_BLOCK)
(insn 23 83 24 3 (set (reg:SI 37)
(const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
{*movsi_immed}
(nil))
(code_label 24 23 84 4 4 (nil) [1 uses])
(note 84 24 25 4 [bb 4] NOTE_INSN_BASIC_BLOCK)
(insn 25 84 26 4 (set (subreg:SI (reg:DI 36) 0)
(plus:SI (subreg:SI (reg:DI 30) 0)
(subreg:SI (reg:DI 33) 0))) "../brew-gcc-
build/second.c":3:10 2 {addsi3}
(expr_list:REG_DEAD (reg:DI 33)
(expr_list:REG_DEAD (reg:DI 30)
(nil))))
(insn 26 25 27 4 (set (reg:SI 38)
(plus:SI (reg:SI 37)
(subreg:SI (reg:DI 36) 0))) "../brew-gcc-
build/second.c":3:10 2 {addsi3}
(expr_list:REG_DEAD (reg:SI 37)
(nil)))
(insn 27 26 28 4 (set (subreg:SI (reg:DI 36) 0)
(reg:SI 38)) "../brew-gcc-build/second.c":3:10 21
{*movsi_move}
(expr_list:REG_DEAD (reg:SI 38)
(nil)))
(insn 28 27 29 4 (set (reg:SI 40)
(mem/c:SI (plus:SI (reg/f:SI 16 ?ap)
(const_int 4 [0x4])) [1 a+0 S4 A32])) "../brew-gcc-
build/second.c":3:10 22 {*movsi_load}
(nil))
(insn 29 28 30 4 (set (subreg:SI (reg:DI 39) 0)
(xor:SI (reg:SI 40)
(reg:SI 40))) "../brew-gcc-build/second.c":3:10 15
{xorsi3}
(expr_list:REG_DEAD (reg:SI 40)
(nil)))
(insn 30 29 31 4 (set (reg:SI 41)
(mem/c:SI (plus:SI (reg/f:SI 16 ?ap)
(const_int 8 [0x8])) [1 a+4 S4 A32])) "../brew-gcc-
build/second.c":3:10 22 {*movsi_load}
(nil))
(insn 31 30 32 4 (set (subreg:SI (reg:DI 39) 4)
(xor:SI (reg:SI 41)
(reg:SI 41))) "../brew-gcc-build/second.c":3:10 15
{xorsi3}
(expr_list:REG_DEAD (reg:SI 41)
(nil)))
(insn 32 31 33 4 (set (reg:SI 43)
(mem/c:SI (plus:SI (reg/f:SI 16 ?ap)
(const_int 4 [0x4])) [1 a+0 S4 A32])) "../brew-gcc-
build/second.c":3:10 22 {*movsi_load}
(nil))
(insn 33 32 34 4 (set (subreg:SI (reg:DI 42) 0)
(xor:SI (reg:SI 43)
(subreg:SI (reg:DI 36) 0))) "../brew-gcc-
build/second.c":3:10 15 {xorsi3}
(expr_list:REG_DEAD (reg:SI 43)
(nil)))
(insn 34 33 35 4 (set (reg:SI 44)
(mem/c:SI (plus:SI (reg/f:SI 16 ?ap)
(const_int 8 [0x8])) [1 a+4 S4 A32])) "../brew-gcc-
build/second.c":3:10 22 {*movsi_load}
(nil))
(insn 35 34 36 4 (set (subreg:SI (reg:DI 42) 4)
(xor:SI (reg:SI 44)
(subreg:SI (reg:DI 36) 4))) "../brew-gcc-
build/second.c":3:10 15 {xorsi3}
(expr_list:REG_DEAD (reg:SI 44)
(nil)))
(insn 36 35 37 4 (set (subreg:SI (reg:DI 45) 0)
(not:SI (subreg:SI (reg:DI 39) 0))) "../brew-gcc-
build/second.c":3:10 12 {one_cmplsi2}
(nil))
(insn 37 36 38 4 (set (subreg:SI (reg:DI 45) 4)
(not:SI (subreg:SI (reg:DI 39) 4))) "../brew-gcc-
build/second.c":3:10 12 {one_cmplsi2}
(expr_list:REG_DEAD (reg:DI 39)
(nil)))
(insn 38 37 39 4 (set (subreg:SI (reg:DI 46) 0)
(and:SI (subreg:SI (reg:DI 42) 0)
(subreg:SI (reg:DI 45) 0))) "../brew-gcc-
build/second.c":3:10 14 {andsi3}
(nil))
(insn 39 38 42 4 (set (subreg:SI (reg:DI 46) 4)
(and:SI (subreg:SI (reg:DI 42) 4)
(subreg:SI (reg:DI 45) 4))) "../brew-gcc-
build/second.c":3:10 14 {andsi3}
(expr_list:REG_DEAD (reg:DI 45)
(expr_list:REG_DEAD (reg:DI 42)
(nil))))
(jump_insn 42 39 85 4 (set (pc)
(if_then_else (ge (subreg:SI (reg:DI 46) 0)
(const_int 0 [0]))
(label_ref 50)
(pc))) "../brew-gcc-build/second.c":3:10 38 {cbranchsi4}
(expr_list:REG_DEAD (reg:DI 46)
(nil))
-> 50)
(note 85 42 49 5 [bb 5] NOTE_INSN_BASIC_BLOCK)
(insn 49 85 47 5 (clobber (reg:DI 27 [ _5+8 ])) "../brew-gcc-
build/second.c":3:10 -1
(nil))
(insn 47 49 48 5 (set (subreg:SI (reg:DI 27 [ _5+8 ]) 0)
(const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
{*movsi_immed}
(nil))
(insn 48 47 50 5 (set (subreg:SI (reg:DI 27 [ _5+8 ]) 4)
(const_int 1 [0x1])) "../brew-gcc-build/second.c":3:10 20
{*movsi_immed}
(nil))
(code_label 50 48 88 6 2 (nil) [1 uses])
(note 88 50 53 6 [bb 6] NOTE_INSN_BASIC_BLOCK)
(insn 53 88 51 6 (clobber (reg:DI 26 [ _5 ])) "../brew-gcc-
build/second.c":3:10 -1
(nil))
(insn 51 53 52 6 (set (subreg:SI (reg:DI 26 [ _5 ]) 0)
(subreg:SI (reg:DI 36) 0)) "../brew-gcc-build/second.c":3:10
21 {*movsi_move}
(nil))
(insn 52 51 56 6 (set (subreg:SI (reg:DI 26 [ _5 ]) 4)
(subreg:SI (reg:DI 36) 4)) "../brew-gcc-build/second.c":3:10
21 {*movsi_move}
(expr_list:REG_DEAD (reg:DI 36)
(nil)))
(insn 56 52 54 6 (clobber (reg:DI 23 [ _1 ])) "../brew-gcc-
build/second.c":3:10 -1
(nil))
(insn 54 56 55 6 (set (subreg:SI (reg:DI 23 [ _1 ]) 0)
(subreg:SI (reg:DI 26 [ _5 ]) 0)) "../brew-gcc-
build/second.c":3:10 21 {*movsi_move}
(nil))
(insn 55 54 57 6 (set (subreg:SI (reg:DI 23 [ _1 ]) 4)
(subreg:SI (reg:DI 26 [ _5 ]) 4)) "../brew-gcc-
build/second.c":3:10 21 {*movsi_move}
(expr_list:REG_DEAD (reg:DI 26 [ _5 ])
(nil)))
(insn 57 55 58 6 (set (reg/f:SI 47)
(mem/f/c:SI (plus:SI (reg/f:SI 16 ?ap)
(const_int 12 [0xc])) [2 w+0 S4 A32])) "../brew-gcc-
build/second.c":3:10 22 {*movsi_load}
(nil))
(insn 58 57 59 6 (set (reg:SI 48)
(subreg:SI (reg:DI 23 [ _1 ]) 0)) "../brew-gcc-
build/second.c":3:10 21 {*movsi_move}
(nil))
(insn 59 58 60 6 (set (mem:SI (reg/f:SI 47) [1 *w_7(D)+0 S4 A32])
(reg:SI 48)) "../brew-gcc-build/second.c":3:10 23
{*movsi_store}
(expr_list:REG_DEAD (reg:SI 48)
(nil)))
(insn 60 59 61 6 (set (reg:SI 49)
(subreg:SI (reg:DI 23 [ _1 ]) 4)) "../brew-gcc-
build/second.c":3:10 21 {*movsi_move}
(expr_list:REG_DEAD (reg:DI 23 [ _1 ])
(nil)))
(insn 61 60 64 6 (set (mem:SI (plus:SI (reg/f:SI 47)
(const_int 4 [0x4])) [1 *w_7(D)+4 S4 A32])
(reg:SI 49)) "../brew-gcc-build/second.c":3:10 23
{*movsi_store}
(expr_list:REG_DEAD (reg:SI 49)
(expr_list:REG_DEAD (reg/f:SI 47)
(nil))))
(insn 64 61 62 6 (clobber (reg:DI 24 [ _2 ])) "../brew-gcc-
build/second.c":3:10 -1
(nil))
(insn 62 64 63 6 (set (subreg:SI (reg:DI 24 [ _2 ]) 0)
(subreg:SI (reg:DI 27 [ _5+8 ]) 0)) "../brew-gcc-
build/second.c":3:10 21 {*movsi_move}
(nil))
(insn 63 62 65 6 (set (subreg:SI (reg:DI 24 [ _2 ]) 4)
(subreg:SI (reg:DI 27 [ _5+8 ]) 4)) "../brew-gcc-
build/second.c":3:10 21 {*movsi_move}
(expr_list:REG_DEAD (reg:DI 27 [ _5+8 ])
(nil)))
(insn 65 63 66 6 (set (reg:QI 25 [ _3 ])
(subreg:QI (reg:DI 24 [ _2 ]) 7)) "../brew-gcc-
build/second.c":3:10 31 {*movqi_move}
(expr_list:REG_DEAD (reg:DI 24 [ _2 ])
(nil)))
(insn 66 65 67 6 (set (reg:SI 50)
(and:SI (subreg:SI (reg:QI 25 [ _3 ]) 0)
(const_int 1 [0x1]))) "../brew-gcc-build/second.c":3:10
14 {andsi3}
(expr_list:REG_DEAD (reg:QI 25 [ _3 ])
(nil)))
(insn 67 66 68 6 (set (reg:QI 25 [ _3 ])
(subreg:QI (reg:SI 50) 3)) "../brew-gcc-build/second.c":3:10
31 {*movqi_move}
(expr_list:REG_DEAD (reg:SI 50)
(nil)))
(insn 68 67 69 6 (set (reg:SI 51)
(zero_extend:SI (reg:QI 25 [ _3 ]))) "../brew-gcc-
build/second.c":3:10 35 {zero_extendqisi2}
(expr_list:REG_DEAD (reg:QI 25 [ _3 ])
(nil)))
(insn 69 68 70 6 (set (subreg:SI (reg:DI 28 [ _9 ]) 4)
(reg:SI 51)) "../brew-gcc-build/second.c":3:10 21
{*movsi_move}
(expr_list:REG_DEAD (reg:SI 51)
(nil)))
(insn 70 69 75 6 (set (subreg:SI (reg:DI 28 [ _9 ]) 0)
(const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
{*movsi_immed}
(nil))
(insn 75 70 73 6 (clobber (reg:DI 29 [ <retval> ])) "../brew-gcc-
build/second.c":3:10 -1
(nil))
(insn 73 75 74 6 (set (subreg:SI (reg:DI 29 [ <retval> ]) 0)
(subreg:SI (reg:DI 28 [ _9 ]) 0)) "../brew-gcc-
build/second.c":3:10 21 {*movsi_move}
(nil))
(insn 74 73 79 6 (set (subreg:SI (reg:DI 29 [ <retval> ]) 4)
(subreg:SI (reg:DI 28 [ _9 ]) 4)) "../brew-gcc-
build/second.c":3:10 21 {*movsi_move}
(expr_list:REG_DEAD (reg:DI 28 [ _9 ])
(nil)))
(insn 79 74 80 6 (set (reg:SI 4 $r4)
(subreg:SI (reg:DI 29 [ <retval> ]) 0)) "../brew-gcc-
build/second.c":5:1 21 {*movsi_move}
(nil))
(insn 80 79 81 6 (set (reg:SI 5 $r5 [orig:4+4 ] [4])
(subreg:SI (reg:DI 29 [ <retval> ]) 4)) "../brew-gcc-
build/second.c":5:1 21 {*movsi_move}
(expr_list:REG_DEAD (reg:DI 29 [ <retval> ])
(nil)))
(insn 81 80 89 6 (use (reg/i:DI 4 $r4)) "../brew-gcc-
build/second.c":5:1 -1
(nil))
(note 89 81 0 NOTE_INSN_DELETED)
What I've noticed when I dump the RTL from LRA during each of its
iterations is the following:
In the first several iterations, LRA proceeds to delete the first
several instructions (all the below gets deleted):
(insn 2 4 3 2 (set (mem/f/c:SI (plus:SI (reg/f:SI 16 ?ap)
(const_int 12 [0xc])) [2 w+0 S4 A32])
(reg:SI 4 $r4)) "../brew-gcc-build/second.c":2:1 23
{*movsi_store}
(expr_list:REG_DEAD (reg:SI 4 $r4)
(nil)))
(note 3 2 8 2 NOTE_INSN_FUNCTION_BEG)
(insn 8 3 6 2 (clobber (reg:DI 27 [ _5+8 ])) "../brew-gcc-
build/second.c":3:10 -1
(nil))
(insn 6 8 7 2 (set (subreg:SI (reg:DI 27 [ _5+8 ]) 0)
(const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
{*movsi_immed}
(nil))
(insn 7 6 13 2 (set (subreg:SI (reg:DI 27 [ _5+8 ]) 4)
(const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
{*movsi_immed}
(nil))
(insn 13 7 18 2 (clobber (reg:DI 30)) "../brew-gcc-
build/second.c":3:10 -1
(nil))
(insn 18 13 19 2 (clobber (reg:DI 33)) "../brew-gcc-
build/second.c":3:10 -1
(nil))
(insn 19 18 20 2 (clobber (reg:DI 36)) "../brew-gcc-
build/second.c":3:10 -1
(nil))
(insn 20 19 21 2 (set (subreg:SI (reg:DI 36) 4)
(plus:SI (subreg:SI (reg:DI 30) 4)
(subreg:SI (reg:DI 33) 4))) "../brew-gcc-
build/second.c":3:10 2 {addsi3}
(nil))
(insn 21 20 22 2 (set (reg:SI 37)
(const_int 1 [0x1])) "../brew-gcc-build/second.c":3:10 20
{*movsi_immed}
(nil))
(jump_insn 22 21 83 2 (set (pc)
(if_then_else (ltu (subreg:SI (reg:DI 36) 4)
(subreg:SI (reg:DI 30) 4))
(label_ref 24)
(pc))) "../brew-gcc-build/second.c":3:10 38 {cbranchsi4}
(nil)
-> 24)
(note 83 22 23 3 [bb 3] NOTE_INSN_BASIC_BLOCK)
(insn 23 83 24 3 (set (reg:SI 37)
(const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
{*movsi_immed}
(nil))
(code_label 24 23 84 4 4 (nil) [1 uses])
(note 84 24 25 4 [bb 4] NOTE_INSN_BASIC_BLOCK)
(insn 25 84 26 4 (set (subreg:SI (reg:DI 36) 0)
(plus:SI (subreg:SI (reg:DI 30) 0)
(subreg:SI (reg:DI 33) 0))) "../brew-gcc-
build/second.c":3:10 2 {addsi3}
(expr_list:REG_DEAD (reg:DI 33)
(expr_list:REG_DEAD (reg:DI 30)
(nil))))
(insn 26 25 27 4 (set (reg:SI 38)
(plus:SI (reg:SI 37)
(subreg:SI (reg:DI 36) 0))) "../brew-gcc-
build/second.c":3:10 2 {addsi3}
(expr_list:REG_DEAD (reg:SI 37)
(nil)))
(insn 27 26 28 4 (set (subreg:SI (reg:DI 36) 0)
(reg:SI 38)) "../brew-gcc-build/second.c":3:10 21
{*movsi_move}
(expr_list:REG_DEAD (reg:SI 38)
(nil)))
(insn 28 27 29 4 (set (reg:SI 40)
(mem/c:SI (plus:SI (reg/f:SI 16 ?ap)
(const_int 4 [0x4])) [1 a+0 S4 A32])) "../brew-gcc-
build/second.c":3:10 22 {*movsi_load}
(nil))
After that, it replaces the XOR with a move:
(insn 29 28 30 4 (set (subreg:SI (reg:DI 39) 0)
(xor:SI (reg:SI 40)
(reg:SI 40))) "../brew-gcc-build/second.c":3:10 15
{xorsi3}
(expr_list:REG_DEAD (reg:SI 40)
(nil)))
to:
(insn 90 29 30 4 (set (subreg:SI (reg:DI 39) 0)
(reg:SI 54)) "../brew-gcc-build/second.c":3:10 21
{*movsi_move}
(nil))
After this, all that's happening is LRA keeps replaceing reg:SI 54 with
newer and newer soft-regs (reg:SI 55, then 56, then 57 etc.) until it
runs out of iterations and blows up.
Now, I'm certain that I'm doing something wrong and it's not a bug in
LRA. But what could the problem be? And how can I get closer to said
problem? Why delete so much of the beginning of the function? And,
while I understand why an xor(something, same thing) can be replaced by
a zeroing of a register, that's not what's done here.
The (hopefully) relevant pieces of machine definition:
(define_constraint "O"
"The constant zero"
(and
(match_code "const_int")
(match_test "ival == 0")
)
)
(define_insn "xorsi3"
[(set
(match_operand:SI 0 "register_operand" "=r,r,r,r")
(xor:SI
(match_operand:SI 1 "register_operand" "r,r,r,r")
(match_operand:SI 2 "nonmemory_operand" "1,O,r,i")
)
)]
""
"@
%0 <- %1 - %1
%0 <- %1
%0 <- %1 ^ %2
%0 <- %1 ^ (%2)"
)
(define_insn "*movsi_move"
[(set
(match_operand:SI 0 "register_operand" "=r")
(match_operand:SI 1 "register_operand" "r")
)]
""
"%0 <- %1"
[(set_attr "length" "2")]
)
(define_insn "*movsi_immed"
[(set
(match_operand:SI 0 "register_operand" "=r,r")
(match_operand:SI 1 "immediate_operand" "O,i")
)]
""
"@
%0 <- %0 - %0
%0 <- %1"
[(set_attr "length" "2,6")]
)
This is quite possibly not enough information for anyone to figure this
out, so please tell me what else should I include to make things more
clear?
Thanks a lot!
Andras
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: What's wrong with this RTL?
2022-01-10 4:48 What's wrong with this RTL? Andras Tantos
@ 2022-01-10 6:19 ` Andrew Pinski
2022-01-11 4:15 ` Andras Tantos
0 siblings, 1 reply; 3+ messages in thread
From: Andrew Pinski @ 2022-01-10 6:19 UTC (permalink / raw)
To: Andras Tantos; +Cc: gcc
On Sun, Jan 9, 2022 at 8:49 PM Andras Tantos <andras@tantosonline.com> wrote:
>
> All!
>
> I'm trying to port GCC to a new target, I call 'brew'. I've based it on
> the Moxie target mostly because of it's simplicity.
>
> I must be doing something horribly wrong as the following C code crokes
> in the LRA path:
>
> long long foo (long long a, long long *w)
> {
> return __builtin_add_overflow (a, a, w);
> }
>
> The error message I get is the following:
>
> during RTL pass: reload
> ../brew-gcc-build/second.c: In function ‘foo’:
> ../brew-gcc-build/second.c:5:1: internal compiler error: maximum
> number of generated reload insns per insn achieved (90)
> 5 | }
> | ^
> 0xd23854 lra_constraints(bool)
> ../../brew-gcc/gcc/lra-constraints.c:5095
> 0xd10322 lra(_IO_FILE*)
> ../../brew-gcc/gcc/lra.c:2336
> 0xcc86d9 do_reload
> ../../brew-gcc/gcc/ira.c:5932
> 0xcc86d9 execute
> ../../brew-gcc/gcc/ira.c:6118
> Please submit a full bug report,
> with preprocessed source if appropriate.
> Please include the complete backtrace with any bug report.
> See <https://gcc.gnu.org/bugs/> for instructions.
This usually means the move instruction is being reloaded over and
over again as you describe below.
I think you should have one merged movsi instruction which handles all
of the constraints together. mov is "special" in that it needs to be
done that way otherwise this happens.
But really there seems to be another issue where (subreg:SI (reg:DI))
is not being accepted for the xor set too.
What regclasses are being chosen for the reg DI mode? Etc.
Thanks,
Andrew Pinski
>
> The repro seems to go away, if:
>
> 1. If I don't use the return value from __builtin_add_overflow
> 2. If I don't return a long long value
> 3. If I use some other function, which is not inlined
> 4. If I write and call some other (somewhat non-trivial) force-inline
> function myself
>
> In other words, this is pretty much the minimal repro, I've found so
> far.
>
> The initial RTL passed in to LRA appears to be:
>
> (insn 2 4 3 2 (set (mem/f/c:SI (plus:SI (reg/f:SI 16 ?ap)
> (const_int 12 [0xc])) [2 w+0 S4 A32])
> (reg:SI 4 $r4)) "../brew-gcc-build/second.c":2:1 23
> {*movsi_store}
> (expr_list:REG_DEAD (reg:SI 4 $r4)
> (nil)))
>
> (note 3 2 8 2 NOTE_INSN_FUNCTION_BEG)
>
> (insn 8 3 6 2 (clobber (reg:DI 27 [ _5+8 ])) "../brew-gcc-
> build/second.c":3:10 -1
> (nil))
>
> (insn 6 8 7 2 (set (subreg:SI (reg:DI 27 [ _5+8 ]) 0)
> (const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
> {*movsi_immed}
> (nil))
>
> (insn 7 6 13 2 (set (subreg:SI (reg:DI 27 [ _5+8 ]) 4)
> (const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
> {*movsi_immed}
> (nil))
>
> (insn 13 7 18 2 (clobber (reg:DI 30)) "../brew-gcc-
> build/second.c":3:10 -1
> (nil))
>
> (insn 18 13 19 2 (clobber (reg:DI 33)) "../brew-gcc-
> build/second.c":3:10 -1
> (nil))
>
> (insn 19 18 20 2 (clobber (reg:DI 36)) "../brew-gcc-
> build/second.c":3:10 -1
> (nil))
>
> (insn 20 19 21 2 (set (subreg:SI (reg:DI 36) 4)
> (plus:SI (subreg:SI (reg:DI 30) 4)
> (subreg:SI (reg:DI 33) 4))) "../brew-gcc-
> build/second.c":3:10 2 {addsi3}
> (nil))
>
> (insn 21 20 22 2 (set (reg:SI 37)
> (const_int 1 [0x1])) "../brew-gcc-build/second.c":3:10 20
> {*movsi_immed}
> (nil))
>
> (jump_insn 22 21 83 2 (set (pc)
> (if_then_else (ltu (subreg:SI (reg:DI 36) 4)
> (subreg:SI (reg:DI 30) 4))
> (label_ref 24)
> (pc))) "../brew-gcc-build/second.c":3:10 38 {cbranchsi4}
> (nil)
> -> 24)
>
> (note 83 22 23 3 [bb 3] NOTE_INSN_BASIC_BLOCK)
>
> (insn 23 83 24 3 (set (reg:SI 37)
> (const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
> {*movsi_immed}
> (nil))
>
> (code_label 24 23 84 4 4 (nil) [1 uses])
>
> (note 84 24 25 4 [bb 4] NOTE_INSN_BASIC_BLOCK)
>
> (insn 25 84 26 4 (set (subreg:SI (reg:DI 36) 0)
> (plus:SI (subreg:SI (reg:DI 30) 0)
> (subreg:SI (reg:DI 33) 0))) "../brew-gcc-
> build/second.c":3:10 2 {addsi3}
> (expr_list:REG_DEAD (reg:DI 33)
> (expr_list:REG_DEAD (reg:DI 30)
> (nil))))
>
> (insn 26 25 27 4 (set (reg:SI 38)
> (plus:SI (reg:SI 37)
> (subreg:SI (reg:DI 36) 0))) "../brew-gcc-
> build/second.c":3:10 2 {addsi3}
> (expr_list:REG_DEAD (reg:SI 37)
> (nil)))
>
> (insn 27 26 28 4 (set (subreg:SI (reg:DI 36) 0)
> (reg:SI 38)) "../brew-gcc-build/second.c":3:10 21
> {*movsi_move}
> (expr_list:REG_DEAD (reg:SI 38)
> (nil)))
>
> (insn 28 27 29 4 (set (reg:SI 40)
> (mem/c:SI (plus:SI (reg/f:SI 16 ?ap)
> (const_int 4 [0x4])) [1 a+0 S4 A32])) "../brew-gcc-
> build/second.c":3:10 22 {*movsi_load}
> (nil))
>
> (insn 29 28 30 4 (set (subreg:SI (reg:DI 39) 0)
> (xor:SI (reg:SI 40)
> (reg:SI 40))) "../brew-gcc-build/second.c":3:10 15
> {xorsi3}
> (expr_list:REG_DEAD (reg:SI 40)
> (nil)))
>
> (insn 30 29 31 4 (set (reg:SI 41)
> (mem/c:SI (plus:SI (reg/f:SI 16 ?ap)
> (const_int 8 [0x8])) [1 a+4 S4 A32])) "../brew-gcc-
> build/second.c":3:10 22 {*movsi_load}
> (nil))
>
> (insn 31 30 32 4 (set (subreg:SI (reg:DI 39) 4)
> (xor:SI (reg:SI 41)
> (reg:SI 41))) "../brew-gcc-build/second.c":3:10 15
> {xorsi3}
> (expr_list:REG_DEAD (reg:SI 41)
> (nil)))
>
> (insn 32 31 33 4 (set (reg:SI 43)
> (mem/c:SI (plus:SI (reg/f:SI 16 ?ap)
> (const_int 4 [0x4])) [1 a+0 S4 A32])) "../brew-gcc-
> build/second.c":3:10 22 {*movsi_load}
> (nil))
>
> (insn 33 32 34 4 (set (subreg:SI (reg:DI 42) 0)
> (xor:SI (reg:SI 43)
> (subreg:SI (reg:DI 36) 0))) "../brew-gcc-
> build/second.c":3:10 15 {xorsi3}
> (expr_list:REG_DEAD (reg:SI 43)
> (nil)))
>
> (insn 34 33 35 4 (set (reg:SI 44)
> (mem/c:SI (plus:SI (reg/f:SI 16 ?ap)
> (const_int 8 [0x8])) [1 a+4 S4 A32])) "../brew-gcc-
> build/second.c":3:10 22 {*movsi_load}
> (nil))
>
> (insn 35 34 36 4 (set (subreg:SI (reg:DI 42) 4)
> (xor:SI (reg:SI 44)
> (subreg:SI (reg:DI 36) 4))) "../brew-gcc-
> build/second.c":3:10 15 {xorsi3}
> (expr_list:REG_DEAD (reg:SI 44)
> (nil)))
>
> (insn 36 35 37 4 (set (subreg:SI (reg:DI 45) 0)
> (not:SI (subreg:SI (reg:DI 39) 0))) "../brew-gcc-
> build/second.c":3:10 12 {one_cmplsi2}
> (nil))
>
> (insn 37 36 38 4 (set (subreg:SI (reg:DI 45) 4)
> (not:SI (subreg:SI (reg:DI 39) 4))) "../brew-gcc-
> build/second.c":3:10 12 {one_cmplsi2}
> (expr_list:REG_DEAD (reg:DI 39)
> (nil)))
>
> (insn 38 37 39 4 (set (subreg:SI (reg:DI 46) 0)
> (and:SI (subreg:SI (reg:DI 42) 0)
> (subreg:SI (reg:DI 45) 0))) "../brew-gcc-
> build/second.c":3:10 14 {andsi3}
> (nil))
>
> (insn 39 38 42 4 (set (subreg:SI (reg:DI 46) 4)
> (and:SI (subreg:SI (reg:DI 42) 4)
> (subreg:SI (reg:DI 45) 4))) "../brew-gcc-
> build/second.c":3:10 14 {andsi3}
> (expr_list:REG_DEAD (reg:DI 45)
> (expr_list:REG_DEAD (reg:DI 42)
> (nil))))
>
> (jump_insn 42 39 85 4 (set (pc)
> (if_then_else (ge (subreg:SI (reg:DI 46) 0)
> (const_int 0 [0]))
> (label_ref 50)
> (pc))) "../brew-gcc-build/second.c":3:10 38 {cbranchsi4}
> (expr_list:REG_DEAD (reg:DI 46)
> (nil))
> -> 50)
>
> (note 85 42 49 5 [bb 5] NOTE_INSN_BASIC_BLOCK)
>
> (insn 49 85 47 5 (clobber (reg:DI 27 [ _5+8 ])) "../brew-gcc-
> build/second.c":3:10 -1
> (nil))
>
> (insn 47 49 48 5 (set (subreg:SI (reg:DI 27 [ _5+8 ]) 0)
> (const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
> {*movsi_immed}
> (nil))
>
> (insn 48 47 50 5 (set (subreg:SI (reg:DI 27 [ _5+8 ]) 4)
> (const_int 1 [0x1])) "../brew-gcc-build/second.c":3:10 20
> {*movsi_immed}
> (nil))
>
> (code_label 50 48 88 6 2 (nil) [1 uses])
>
> (note 88 50 53 6 [bb 6] NOTE_INSN_BASIC_BLOCK)
>
> (insn 53 88 51 6 (clobber (reg:DI 26 [ _5 ])) "../brew-gcc-
> build/second.c":3:10 -1
> (nil))
>
> (insn 51 53 52 6 (set (subreg:SI (reg:DI 26 [ _5 ]) 0)
> (subreg:SI (reg:DI 36) 0)) "../brew-gcc-build/second.c":3:10
> 21 {*movsi_move}
> (nil))
>
> (insn 52 51 56 6 (set (subreg:SI (reg:DI 26 [ _5 ]) 4)
> (subreg:SI (reg:DI 36) 4)) "../brew-gcc-build/second.c":3:10
> 21 {*movsi_move}
> (expr_list:REG_DEAD (reg:DI 36)
> (nil)))
>
> (insn 56 52 54 6 (clobber (reg:DI 23 [ _1 ])) "../brew-gcc-
> build/second.c":3:10 -1
> (nil))
>
> (insn 54 56 55 6 (set (subreg:SI (reg:DI 23 [ _1 ]) 0)
> (subreg:SI (reg:DI 26 [ _5 ]) 0)) "../brew-gcc-
> build/second.c":3:10 21 {*movsi_move}
> (nil))
>
> (insn 55 54 57 6 (set (subreg:SI (reg:DI 23 [ _1 ]) 4)
> (subreg:SI (reg:DI 26 [ _5 ]) 4)) "../brew-gcc-
> build/second.c":3:10 21 {*movsi_move}
> (expr_list:REG_DEAD (reg:DI 26 [ _5 ])
> (nil)))
>
> (insn 57 55 58 6 (set (reg/f:SI 47)
> (mem/f/c:SI (plus:SI (reg/f:SI 16 ?ap)
> (const_int 12 [0xc])) [2 w+0 S4 A32])) "../brew-gcc-
> build/second.c":3:10 22 {*movsi_load}
> (nil))
>
> (insn 58 57 59 6 (set (reg:SI 48)
> (subreg:SI (reg:DI 23 [ _1 ]) 0)) "../brew-gcc-
> build/second.c":3:10 21 {*movsi_move}
> (nil))
>
> (insn 59 58 60 6 (set (mem:SI (reg/f:SI 47) [1 *w_7(D)+0 S4 A32])
> (reg:SI 48)) "../brew-gcc-build/second.c":3:10 23
> {*movsi_store}
> (expr_list:REG_DEAD (reg:SI 48)
> (nil)))
>
> (insn 60 59 61 6 (set (reg:SI 49)
> (subreg:SI (reg:DI 23 [ _1 ]) 4)) "../brew-gcc-
> build/second.c":3:10 21 {*movsi_move}
> (expr_list:REG_DEAD (reg:DI 23 [ _1 ])
> (nil)))
>
> (insn 61 60 64 6 (set (mem:SI (plus:SI (reg/f:SI 47)
> (const_int 4 [0x4])) [1 *w_7(D)+4 S4 A32])
> (reg:SI 49)) "../brew-gcc-build/second.c":3:10 23
> {*movsi_store}
> (expr_list:REG_DEAD (reg:SI 49)
> (expr_list:REG_DEAD (reg/f:SI 47)
> (nil))))
>
> (insn 64 61 62 6 (clobber (reg:DI 24 [ _2 ])) "../brew-gcc-
> build/second.c":3:10 -1
> (nil))
>
> (insn 62 64 63 6 (set (subreg:SI (reg:DI 24 [ _2 ]) 0)
> (subreg:SI (reg:DI 27 [ _5+8 ]) 0)) "../brew-gcc-
> build/second.c":3:10 21 {*movsi_move}
> (nil))
>
> (insn 63 62 65 6 (set (subreg:SI (reg:DI 24 [ _2 ]) 4)
> (subreg:SI (reg:DI 27 [ _5+8 ]) 4)) "../brew-gcc-
> build/second.c":3:10 21 {*movsi_move}
> (expr_list:REG_DEAD (reg:DI 27 [ _5+8 ])
> (nil)))
>
> (insn 65 63 66 6 (set (reg:QI 25 [ _3 ])
> (subreg:QI (reg:DI 24 [ _2 ]) 7)) "../brew-gcc-
> build/second.c":3:10 31 {*movqi_move}
> (expr_list:REG_DEAD (reg:DI 24 [ _2 ])
> (nil)))
>
> (insn 66 65 67 6 (set (reg:SI 50)
> (and:SI (subreg:SI (reg:QI 25 [ _3 ]) 0)
> (const_int 1 [0x1]))) "../brew-gcc-build/second.c":3:10
> 14 {andsi3}
> (expr_list:REG_DEAD (reg:QI 25 [ _3 ])
> (nil)))
>
> (insn 67 66 68 6 (set (reg:QI 25 [ _3 ])
> (subreg:QI (reg:SI 50) 3)) "../brew-gcc-build/second.c":3:10
> 31 {*movqi_move}
> (expr_list:REG_DEAD (reg:SI 50)
> (nil)))
>
> (insn 68 67 69 6 (set (reg:SI 51)
> (zero_extend:SI (reg:QI 25 [ _3 ]))) "../brew-gcc-
> build/second.c":3:10 35 {zero_extendqisi2}
> (expr_list:REG_DEAD (reg:QI 25 [ _3 ])
> (nil)))
>
> (insn 69 68 70 6 (set (subreg:SI (reg:DI 28 [ _9 ]) 4)
> (reg:SI 51)) "../brew-gcc-build/second.c":3:10 21
> {*movsi_move}
> (expr_list:REG_DEAD (reg:SI 51)
> (nil)))
>
> (insn 70 69 75 6 (set (subreg:SI (reg:DI 28 [ _9 ]) 0)
> (const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
> {*movsi_immed}
> (nil))
>
> (insn 75 70 73 6 (clobber (reg:DI 29 [ <retval> ])) "../brew-gcc-
> build/second.c":3:10 -1
> (nil))
>
> (insn 73 75 74 6 (set (subreg:SI (reg:DI 29 [ <retval> ]) 0)
> (subreg:SI (reg:DI 28 [ _9 ]) 0)) "../brew-gcc-
> build/second.c":3:10 21 {*movsi_move}
> (nil))
>
> (insn 74 73 79 6 (set (subreg:SI (reg:DI 29 [ <retval> ]) 4)
> (subreg:SI (reg:DI 28 [ _9 ]) 4)) "../brew-gcc-
> build/second.c":3:10 21 {*movsi_move}
> (expr_list:REG_DEAD (reg:DI 28 [ _9 ])
> (nil)))
>
> (insn 79 74 80 6 (set (reg:SI 4 $r4)
> (subreg:SI (reg:DI 29 [ <retval> ]) 0)) "../brew-gcc-
> build/second.c":5:1 21 {*movsi_move}
> (nil))
>
> (insn 80 79 81 6 (set (reg:SI 5 $r5 [orig:4+4 ] [4])
> (subreg:SI (reg:DI 29 [ <retval> ]) 4)) "../brew-gcc-
> build/second.c":5:1 21 {*movsi_move}
> (expr_list:REG_DEAD (reg:DI 29 [ <retval> ])
> (nil)))
>
> (insn 81 80 89 6 (use (reg/i:DI 4 $r4)) "../brew-gcc-
> build/second.c":5:1 -1
> (nil))
>
> (note 89 81 0 NOTE_INSN_DELETED)
>
> What I've noticed when I dump the RTL from LRA during each of its
> iterations is the following:
>
> In the first several iterations, LRA proceeds to delete the first
> several instructions (all the below gets deleted):
>
> (insn 2 4 3 2 (set (mem/f/c:SI (plus:SI (reg/f:SI 16 ?ap)
> (const_int 12 [0xc])) [2 w+0 S4 A32])
> (reg:SI 4 $r4)) "../brew-gcc-build/second.c":2:1 23
> {*movsi_store}
> (expr_list:REG_DEAD (reg:SI 4 $r4)
> (nil)))
>
> (note 3 2 8 2 NOTE_INSN_FUNCTION_BEG)
>
> (insn 8 3 6 2 (clobber (reg:DI 27 [ _5+8 ])) "../brew-gcc-
> build/second.c":3:10 -1
> (nil))
>
> (insn 6 8 7 2 (set (subreg:SI (reg:DI 27 [ _5+8 ]) 0)
> (const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
> {*movsi_immed}
> (nil))
>
> (insn 7 6 13 2 (set (subreg:SI (reg:DI 27 [ _5+8 ]) 4)
> (const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
> {*movsi_immed}
> (nil))
>
> (insn 13 7 18 2 (clobber (reg:DI 30)) "../brew-gcc-
> build/second.c":3:10 -1
> (nil))
>
> (insn 18 13 19 2 (clobber (reg:DI 33)) "../brew-gcc-
> build/second.c":3:10 -1
> (nil))
>
> (insn 19 18 20 2 (clobber (reg:DI 36)) "../brew-gcc-
> build/second.c":3:10 -1
> (nil))
>
> (insn 20 19 21 2 (set (subreg:SI (reg:DI 36) 4)
> (plus:SI (subreg:SI (reg:DI 30) 4)
> (subreg:SI (reg:DI 33) 4))) "../brew-gcc-
> build/second.c":3:10 2 {addsi3}
> (nil))
>
> (insn 21 20 22 2 (set (reg:SI 37)
> (const_int 1 [0x1])) "../brew-gcc-build/second.c":3:10 20
> {*movsi_immed}
> (nil))
>
> (jump_insn 22 21 83 2 (set (pc)
> (if_then_else (ltu (subreg:SI (reg:DI 36) 4)
> (subreg:SI (reg:DI 30) 4))
> (label_ref 24)
> (pc))) "../brew-gcc-build/second.c":3:10 38 {cbranchsi4}
> (nil)
> -> 24)
>
> (note 83 22 23 3 [bb 3] NOTE_INSN_BASIC_BLOCK)
>
> (insn 23 83 24 3 (set (reg:SI 37)
> (const_int 0 [0])) "../brew-gcc-build/second.c":3:10 20
> {*movsi_immed}
> (nil))
>
> (code_label 24 23 84 4 4 (nil) [1 uses])
>
> (note 84 24 25 4 [bb 4] NOTE_INSN_BASIC_BLOCK)
>
> (insn 25 84 26 4 (set (subreg:SI (reg:DI 36) 0)
> (plus:SI (subreg:SI (reg:DI 30) 0)
> (subreg:SI (reg:DI 33) 0))) "../brew-gcc-
> build/second.c":3:10 2 {addsi3}
> (expr_list:REG_DEAD (reg:DI 33)
> (expr_list:REG_DEAD (reg:DI 30)
> (nil))))
>
> (insn 26 25 27 4 (set (reg:SI 38)
> (plus:SI (reg:SI 37)
> (subreg:SI (reg:DI 36) 0))) "../brew-gcc-
> build/second.c":3:10 2 {addsi3}
> (expr_list:REG_DEAD (reg:SI 37)
> (nil)))
>
> (insn 27 26 28 4 (set (subreg:SI (reg:DI 36) 0)
> (reg:SI 38)) "../brew-gcc-build/second.c":3:10 21
> {*movsi_move}
> (expr_list:REG_DEAD (reg:SI 38)
> (nil)))
>
> (insn 28 27 29 4 (set (reg:SI 40)
> (mem/c:SI (plus:SI (reg/f:SI 16 ?ap)
> (const_int 4 [0x4])) [1 a+0 S4 A32])) "../brew-gcc-
> build/second.c":3:10 22 {*movsi_load}
> (nil))
>
> After that, it replaces the XOR with a move:
>
> (insn 29 28 30 4 (set (subreg:SI (reg:DI 39) 0)
> (xor:SI (reg:SI 40)
> (reg:SI 40))) "../brew-gcc-build/second.c":3:10 15
> {xorsi3}
> (expr_list:REG_DEAD (reg:SI 40)
> (nil)))
>
> to:
>
> (insn 90 29 30 4 (set (subreg:SI (reg:DI 39) 0)
> (reg:SI 54)) "../brew-gcc-build/second.c":3:10 21
> {*movsi_move}
> (nil))
>
> After this, all that's happening is LRA keeps replaceing reg:SI 54 with
> newer and newer soft-regs (reg:SI 55, then 56, then 57 etc.) until it
> runs out of iterations and blows up.
>
> Now, I'm certain that I'm doing something wrong and it's not a bug in
> LRA. But what could the problem be? And how can I get closer to said
> problem? Why delete so much of the beginning of the function? And,
> while I understand why an xor(something, same thing) can be replaced by
> a zeroing of a register, that's not what's done here.
>
> The (hopefully) relevant pieces of machine definition:
>
> (define_constraint "O"
> "The constant zero"
> (and
> (match_code "const_int")
> (match_test "ival == 0")
> )
> )
>
> (define_insn "xorsi3"
> [(set
> (match_operand:SI 0 "register_operand" "=r,r,r,r")
> (xor:SI
> (match_operand:SI 1 "register_operand" "r,r,r,r")
> (match_operand:SI 2 "nonmemory_operand" "1,O,r,i")
> )
> )]
> ""
> "@
> %0 <- %1 - %1
> %0 <- %1
> %0 <- %1 ^ %2
> %0 <- %1 ^ (%2)"
> )
>
> (define_insn "*movsi_move"
> [(set
> (match_operand:SI 0 "register_operand" "=r")
> (match_operand:SI 1 "register_operand" "r")
> )]
> ""
> "%0 <- %1"
> [(set_attr "length" "2")]
> )
>
>
> (define_insn "*movsi_immed"
> [(set
> (match_operand:SI 0 "register_operand" "=r,r")
> (match_operand:SI 1 "immediate_operand" "O,i")
> )]
> ""
> "@
> %0 <- %0 - %0
> %0 <- %1"
> [(set_attr "length" "2,6")]
> )
>
> This is quite possibly not enough information for anyone to figure this
> out, so please tell me what else should I include to make things more
> clear?
>
> Thanks a lot!
> Andras
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: What's wrong with this RTL?
2022-01-10 6:19 ` Andrew Pinski
@ 2022-01-11 4:15 ` Andras Tantos
0 siblings, 0 replies; 3+ messages in thread
From: Andras Tantos @ 2022-01-11 4:15 UTC (permalink / raw)
To: Andrew Pinski; +Cc: gcc
On Sun, 2022-01-09 at 22:19 -0800, Andrew Pinski wrote:
> On Sun, Jan 9, 2022 at 8:49 PM Andras Tantos <andras@tantosonline.com
> > wrote:
> > All!
> >
> > I'm trying to port GCC to a new target, I call 'brew'. I've based
> > it on
> > the Moxie target mostly because of it's simplicity.
> >
> > I must be doing something horribly wrong as the following C code
> > crokes
> > in the LRA path:
> >
> > long long foo (long long a, long long *w)
> > {
> > return __builtin_add_overflow (a, a, w);
> > }
> >
> > The error message I get is the following:
> >
> > during RTL pass: reload
> > ../brew-gcc-build/second.c: In function ‘foo’:
> > ../brew-gcc-build/second.c:5:1: internal compiler error: maximum
> > number of generated reload insns per insn achieved (90)
> > 5 | }
> > | ^
> > 0xd23854 lra_constraints(bool)
> > ../../brew-gcc/gcc/lra-constraints.c:5095
> > 0xd10322 lra(_IO_FILE*)
> > ../../brew-gcc/gcc/lra.c:2336
> > 0xcc86d9 do_reload
> > ../../brew-gcc/gcc/ira.c:5932
> > 0xcc86d9 execute
> > ../../brew-gcc/gcc/ira.c:6118
> > Please submit a full bug report,
> > with preprocessed source if appropriate.
> > Please include the complete backtrace with any bug report.
> > See <https://gcc.gnu.org/bugs/> for instructions.
>
> This usually means the move instruction is being reloaded over and
> over again as you describe below.
> I think you should have one merged movsi instruction which handles
> all
> of the constraints together. mov is "special" in that it needs to be
> done that way otherwise this happens.
> But really there seems to be another issue where (subreg:SI (reg:DI))
> is not being accepted for the xor set too.
> What regclasses are being chosen for the reg DI mode? Etc.
>
> Thanks,
> Andrew Pinski
>
That's what it was: after merging all my movsi variants, the problem
went away.
Thanks for the help!
Andras
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-01-10 4:48 What's wrong with this RTL? Andras Tantos
2022-01-10 6:19 ` Andrew Pinski
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This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).