http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60663
Bug ID: 60663
Summary: Errors out on valid inline asm
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: zhenqiang.chen at linaro dot org
Found while building an arm32 kernel
//fail.c
int g(void)
{
unsigned i, j;
asm("// %0 %1" : "=r" (i), "=r"(j));
return i;
}
arm-linux-gnueabihf-gcc -march=armv7-a -O2 -c fail.c
fail.c: In function ‘g’:
fail.c:4:3: error: invalid 'asm': operand number out of range
Root cause: "cse1" generates illegal asm instruction since check_asm_operands
does not check the number of expected operands.
i.e. "cse1" changes code from
(insn 5 2 6 2 (parallel [
(set (reg:SI 114 [ i ])
(asm_operands:SI ("// %0 %1") ("=r") 0 []
[]
[] fail.c:4))
(set (reg:SI 115 [ j ])
(asm_operands:SI ("// %0 %1") ("=r") 1 []
[]
[] fail.c:4))
]) fail.c:4 -1
(nil))
(insn 6 5 8 2 (set (reg/v:SI 110 [ i ])
(reg:SI 114 [ i ])) fail.c:4 664 {*thumb2_movsi_vfp}
(nil))
to
(insn 12 2 13 2 (set (reg/i:SI 0 r0)
(asm_operands:SI ("// %0 %1") ("=r") 0 []
[]
[] fail.c:4)) fail.c:6 -1
(nil))
No error for x86-64 and arm gcc-4.8. ARM rtx_cost changes in 4.9 trigger this
optimization.
A patch to enhance check_asm_operands is sent out for review.
