[armel, neon] ICE in reload_cse_simplify_operands, at postreload.c:402

[Rafał Krypa]

Compilation with options "-c -mfloat-abi=softfp -mfpu=neon -O2" of the following code:

#include <arm_neon.h>

void test(int16_t *output)
{
 int16x4_t a, b;
 int16x4x4_t z;
 z.val[0] = vadd_s16(a, b);
 z.val[1] = vadd_s16(a, b);
 z.val[2] = vsub_s16(a, b);
 z.val[3] = vadd_s16(a, b);

 vst4_lane_s16(&output[0], z, 0);
 vst4_lane_s16(&output[8], z, 1);
}

Causes ICE:

insn-unsat-constr.c: In function ‘test’:
insn-unsat-constr.c:7:21: warning: ‘a’ is used uninitialized in this function
insn-unsat-constr.c:7:21: warning: ‘b’ is used uninitialized in this function
insn-unsat-constr.c:14:1: error: insn does not satisfy its constraints:
(insn 34 13 18 2 /usr/lib/gcc/arm-linux-gnueabi/4.5.2/include/arm_neon.h:10277 (set (reg:OI 95 d16 [orig:147 __b ] [147])
        (mem/s/c:OI (pre_dec:SI (reg/f:SI 3 r3 [146])) [3 __b+0 S32 A64])) 739 {*neon_movoi} (expr_list:REG_INC (reg/f:SI 3 r3 [146])
        (nil)))
insn-unsat-constr.c:14:1: internal compiler error: in reload_cse_simplify_operands, at postreload.c:402

The error doesn't occur when optimization is turned off (-O0).

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: gcc-4.5-arm-linux-gnueabi 4.5.2-3ubuntu3cross1.46
ProcVersionSignature:

Uname: Linux 2.6.37-iceberg1 x86_64
NonfreeKernelModules: nvidia
Architecture: amd64
Date: Tue Mar 29 12:37:50 2011
InstallationMedia: Mythbuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
SourcePackage: gcc-4.5-armel-cross

[Ira Rosen (irar)]

I am out of the office until 17/04/2011.

Note: This is an automated response to your message "[Bug 744884] Re:
[armel, neon] ICE in reload_cse_simplify_operands, at postreload.c:402"
sent on 15/4/2011 3:15:49.

This is the only notification you will receive while this person is away.

[Michael Hope (michaelh1)]

Confirmed in gcc-linaro-4.5+bzr99492:

michaelh@ursa1:~/linaro/bugs$ ../toolchains/gcc-linaro-4.5+bzr99492-armv7l-maverick-cbuild108-ursa3-cortexa9r1/bin/gcc -O2 -mfpu=neon -S insn-unsat-constr.i
insn-unsat-constr.c: In function 'test':
insn-unsat-constr.c:19:1: error: insn does not satisfy its constraints:
(insn 41 22 27 2 /usr/lib/gcc/arm-linux-gnueabi/4.5.2/include/arm_neon.h:10277 (set (reg:OI 95 d16 [orig:154 __b ] [154])
        (mem/s/c:OI (pre_dec:SI (reg/f:SI 3 r3 [153])) [5 __b+0 S32 A64])) 786 {*neon_movoi} (expr_list:REG_INC (reg/f:SI 3 r3 [153])
        (nil)))
insn-unsat-constr.c:19:1: internal compiler error: in reload_cse_simplify_operands, at postreload.c:402

Also occurs on the GCC 4.5 release branch:

michaelh@ursa1:~/linaro/bugs$ /tools/toolchains/gcc-4.5.2-armv7l-maverick-cbuild93-ursa1-cortexa8r1/bin/gcc -O2 -mfpu=neon -S insn-unsat-constr.i
insn-unsat-constr.c: In function 'test':
insn-unsat-constr.c:19:1: error: insn does not satisfy its constraints:
(insn 41 22 27 2 /usr/lib/gcc/arm-linux-gnueabi/4.5.2/include/arm_neon.h:10277 (set (reg:OI 95 d16 [orig:154 __b ] [154])
        (mem/s/c:OI (pre_dec:SI (reg/f:SI 3 r3 [153])) [5 __b+0 S32 A64])) 731 {*neon_movoi} (expr_list:REG_INC (reg/f:SI 3 r3 [153])
        (nil)))
insn-unsat-constr.c:19:1: internal compiler error: in reload_cse_simplify_operands, at postreload.c:396

Does not occur in the GCC 4.6.0 release:

michaelh@ursa1:~/linaro/bugs$ /tools/toolchains/gcc-4.6.0-armv7l-maverick-cbuild93-ursa1-cortexa8r1/bin/gcc -O2 -mfpu=neon -S insn-unsat-constr.i

[Michael Hope (michaelh1)]

Could you please also log a ticket in GCC bugzilla as this problem also occurs on the 4.5 branch?