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5cc1d83209
When updating the value of the stack pointer through a sequence of instruc-
tions, only the last instruction in the sequence must modify the stack
pointer, because the stack pointer may be referenced by an interrupt or
other event during the sequence:
/* example */
register void *stack_ptr asm ("a1");
void test(void) {
stack_ptr = (void *)0x04000000;
}
;; before (-O -mabi=call0)
test:
movi.n sp, 1 ;; An interrupt may occur
slli sp, sp, 26 ;; between these instructions
ret.n
This patch avoids this problem by excluding constant value assignments to
the stack pointer from 'constantsynth'.
;; after (-O -mabi=call0)
.literal_position
.literal .LC0, 67108864
test:
l32r sp, .LC0
ret.n
gcc/ChangeLog:
* config/xtensa/xtensa.cc (constantsynth_pass1):
Add the case where the assignment destination is a stack pointer
to the exclusion criteria for processing.
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