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.
---
gcc/config/xtensa/xtensa.cc | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gcc/config/xtensa/xtensa.cc b/gcc/config/xtensa/xtensa.cc
index ff3801194fd..c2a6a161066 100644
--- a/gcc/config/xtensa/xtensa.cc
+++ b/gcc/config/xtensa/xtensa.cc
@@ -6028,7 +6028,7 @@ constantsynth_pass1 (rtx_insn *insn, constantsynth_info
&info)
constant. */
if (GET_CODE (pat = PATTERN (insn)) != SET
|| ! REG_P (dest = SET_DEST (pat)) || ! GP_REG_P (REGNO (dest))
- || GET_MODE (dest) != SImode
+ || GET_MODE (dest) != SImode || rtx_equal_p (dest, stack_pointer_rtx)
|| ! CONST_INT_P (src = avoid_constant_pool_reference (SET_SRC (pat))))
return false;
--
2.39.5
