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AArch64: use stable sorting in generating ldp/stp

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In some corner cases, we have code as below:
  [base + 0x310] = A
  [base + 0x320] = B
  [base + 0x330] = C
  [base + 0x320] = D
unstable sorting could result in wrong value in offset 0x320.  The
patch fixes it by using gcc_stablesort.

2021-07-28  Bin Cheng  <bin.cheng@linux.alibaba.com>

	* config/aarch64/aarch64.c (aarch64_gen_adjusted_ldpstp): use
	gcc_stablesort.
This commit is contained in:
Bin Cheng 2021-07-28 17:50:59 +08:00
parent 0f95c6b2f7
commit b662250c1f
1 changed files with 10 additions and 2 deletions
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12
gcc/config/aarch64/aarch64.c
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@ -24441,8 +24441,16 @@ aarch64_gen_adjusted_ldpstp (rtx *operands, bool load,
for (int i = 0; i < 8; i ++)
temp_operands[i] = operands[i];
/* Sort the operands. */
qsort (temp_operands, 4, 2 * sizeof (rtx *), aarch64_ldrstr_offset_compare);
/* Sort the operands. Note for cases as below:
[base + 0x310] = A
[base + 0x320] = B
[base + 0x330] = C
[base + 0x320] = D
We need stable sorting otherwise wrong data may be store to offset 0x320.
Also note the dead store in above case should be optimized away, but no
guarantees here. */
gcc_stablesort(temp_operands, 4, 2 * sizeof (rtx *),
aarch64_ldrstr_offset_compare);
/* Copy the memory operands so that if we have to bail for some
reason the original addresses are unchanged. */