[gcc r13-6409] vect: Fix voluntarily-masked negative conditionals [PR108430]

[gcc r13-6409] vect: Fix voluntarily-masked negative conditionals [PR108430]

[Richard Sandiford]

https://gcc.gnu.org/g:2a8ce4b52f5892a10a02b94d7be689e59a444ff6

commit r13-6409-g2a8ce4b52f5892a10a02b94d7be689e59a444ff6
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Thu Mar 2 10:30:20 2023 +0000

    vect: Fix voluntarily-masked negative conditionals [PR108430]
    
    vectorizable_condition checks whether a COND_EXPR condition is used
    elsewhere with a loop mask.  If so, it applies the loop mask to the
    COND_EXPR too, to reduce the number of live masks and to increase the
    chance of combining the AND with the comparison.
    
    There is also code to do this for inverted conditions.  E.g. if
    we have a < b ? c : d and something else is conditional on !(a < b)
    (such as a load in d), we use !(a < b) ? d : c and apply the loop
    mask to !(a < b).
    
    This inversion relied on the function's bitop1/bitop2 mechanism.
    However, that mechanism is skipped if the condition is split out of
    the COND_EXPR as a separate statement.  This meant that we could end
    up using the inverse of the intended condition.
    
    There is a separate way of negating the condition when a mask
    is being applied (which is also used for EXTRACT_LAST reductions).
    This patch uses that instead.
    
    As well as the testcase, this fixes aarch64/sve/vcond_{4,17}_run.c.
    
    gcc/
            PR tree-optimization/108430
            * tree-vect-stmts.cc (vectorizable_condition): Fix handling
            of inverted condition.
    
    gcc/testsuite/
            PR tree-optimization/108430
            * gcc.target/aarch64/sve/pr108430.c: New test.

Diff:
---
 gcc/testsuite/gcc.target/aarch64/sve/pr108430.c | 21 +++++++++++++++++++++
 gcc/tree-vect-stmts.cc                          |  3 +--
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/gcc/testsuite/gcc.target/aarch64/sve/pr108430.c b/gcc/testsuite/gcc.target/aarch64/sve/pr108430.c
new file mode 100644
index 00000000000..e7ce0f6d793
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/pr108430.c
@@ -0,0 +1,21 @@
+/* { dg-do run { target aarch64_sve512_hw } } */
+/* { dg-options "-O3 -msve-vector-bits=512" } */
+
+long d = 1;
+static int i = 37;
+static unsigned long a[22];
+static unsigned short c[22];
+static unsigned g[80];
+static unsigned short *h = c;
+static unsigned long *j = a;
+int main() {
+  for (long m = 0; m < 8; ++m)
+    d = 1;
+  for (unsigned char p = 0; p < 17; p += 2)
+  {
+    long t = h[p] ? i : j[p];
+    g[p] = t;
+  }
+  if (g[0])
+    __builtin_abort ();
+}
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index 9e5ffbe252e..77ad8b78506 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -10756,11 +10756,10 @@ vectorizable_condition (vec_info *vinfo,
 		  cond.code = orig_code;
 		  if (loop_vinfo->scalar_cond_masked_set.contains (cond))
 		    {
-		      bitop1 = orig_code;
-		      bitop2 = BIT_NOT_EXPR;
 		      masks = &LOOP_VINFO_MASKS (loop_vinfo);
 		      cond_code = cond.code;
 		      swap_cond_operands = true;
+		      must_invert_cmp_result = true;
 		    }
 		}
 	    }