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* [gcc r14-1507] Fix PR 110042: ifcvt regression due to paradoxical subregs
@ 2023-06-02 19:30 Andrew Pinski
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From: Andrew Pinski @ 2023-06-02 19:30 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:df0853d72d38247aed577a4511450c91794f2f06
commit r14-1507-gdf0853d72d38247aed577a4511450c91794f2f06
Author: Andrew Pinski <apinski@marvell.com>
Date: Tue May 30 15:54:32 2023 -0700
Fix PR 110042: ifcvt regression due to paradoxical subregs
After r14-1014-gc5df248509b489364c573e8, GCC started to emit
directly a zero_extract for `(t1&0x8)!=0`. This introduced
a small regression where ifcvt would not do the ifconversion
as there is now a paradoxical subreg in the dest which
was being rejected. Since paradoxical subreg set the whole
register, we can treat it as the same as a reg in the two places.
OK? Bootstrapped and tested on x86_64-linux-gnu and aarch64-linux-gnu.
gcc/ChangeLog:
PR rtl-optimization/110042
* ifcvt.cc (bbs_ok_for_cmove_arith): Allow paradoxical subregs.
(bb_valid_for_noce_process_p): Strip the subreg for the SET_DEST.
gcc/testsuite/ChangeLog:
PR rtl-optimization/110042
* gcc.target/aarch64/csel_bfx_2.c: New test.
Diff:
---
gcc/ifcvt.cc | 14 +++++++++-----
gcc/testsuite/gcc.target/aarch64/csel_bfx_2.c | 27 +++++++++++++++++++++++++++
2 files changed, 36 insertions(+), 5 deletions(-)
diff --git a/gcc/ifcvt.cc b/gcc/ifcvt.cc
index 868eda93251..0b180b4568f 100644
--- a/gcc/ifcvt.cc
+++ b/gcc/ifcvt.cc
@@ -2022,7 +2022,7 @@ bbs_ok_for_cmove_arith (basic_block bb_a, basic_block bb_b, rtx to_rename)
}
/* Make sure this is a REG and not some instance
- of ZERO_EXTRACT or SUBREG or other dangerous stuff.
+ of ZERO_EXTRACT or non-paradoxical SUBREG or other dangerous stuff.
If we have a memory destination then we have a pair of simple
basic blocks performing an operation of the form [addr] = c ? a : b.
bb_valid_for_noce_process_p will have ensured that these are
@@ -2030,7 +2030,8 @@ bbs_ok_for_cmove_arith (basic_block bb_a, basic_block bb_b, rtx to_rename)
to be renamed. Assert that the callers set this up properly. */
if (MEM_P (SET_DEST (sset_b)))
gcc_assert (rtx_equal_p (SET_DEST (sset_b), to_rename));
- else if (!REG_P (SET_DEST (sset_b)))
+ else if (!REG_P (SET_DEST (sset_b))
+ && !paradoxical_subreg_p (SET_DEST (sset_b)))
{
BITMAP_FREE (bba_sets);
return false;
@@ -3136,14 +3137,17 @@ bb_valid_for_noce_process_p (basic_block test_bb, rtx cond,
rtx sset = single_set (insn);
gcc_assert (sset);
+ rtx dest = SET_DEST (sset);
+ if (SUBREG_P (dest))
+ dest = SUBREG_REG (dest);
if (contains_mem_rtx_p (SET_SRC (sset))
- || !REG_P (SET_DEST (sset))
- || reg_overlap_mentioned_p (SET_DEST (sset), cond))
+ || !REG_P (dest)
+ || reg_overlap_mentioned_p (dest, cond))
goto free_bitmap_and_fail;
potential_cost += pattern_cost (sset, speed_p);
- bitmap_set_bit (test_bb_temps, REGNO (SET_DEST (sset)));
+ bitmap_set_bit (test_bb_temps, REGNO (dest));
}
}
diff --git a/gcc/testsuite/gcc.target/aarch64/csel_bfx_2.c b/gcc/testsuite/gcc.target/aarch64/csel_bfx_2.c
new file mode 100644
index 00000000000..c3b8a6f45cc
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/csel_bfx_2.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+unsigned
+f1(int t, int t1)
+{
+ int tt = 0;
+ if(t)
+ tt = (t1&0x8)!=0;
+ return tt;
+}
+struct f
+{
+ unsigned t:3;
+ unsigned t1:4;
+};
+unsigned
+f2(int t, struct f y)
+{
+ int tt = 0;
+ if(t)
+ tt = y.t1;
+ return tt;
+}
+/* Both f1 and f2 should produce a csel and not a cbz on the argument. */
+/* { dg-final { scan-assembler-times "csel\t" 2 } } */
+/* { dg-final { scan-assembler-times "ubfx\t" 2 } } */
+/* { dg-final { scan-assembler-not "cbz\t" } } */
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