[gcc r10-10464] middle-end/103181 - fix operation_could_trap_p for vector division

[Richard Biener]

https://gcc.gnu.org/g:5f5c26a2f02572996efd2b2de0dd5600ad7e91e7

commit r10-10464-g5f5c26a2f02572996efd2b2de0dd5600ad7e91e7
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Nov 11 09:40:36 2021 +0100

    middle-end/103181 - fix operation_could_trap_p for vector division
    
    For integer vector division we only checked for all zero vector
    constants rather than checking whether any element in the constant
    vector is zero.
    
    It also fixes the adjustment to operation_could_trap_helper_p
    where I failed to realize that RDIV_EXPR is also used for
    fixed-point types.  It also fixes that handling by properly
    checking for a fixed_zerop divisor.
    
    2021-11-11  Richard Biener  <rguenther@suse.de>
    
            PR middle-end/103181
            PR middle-end/103248
            * tree-eh.c (operation_could_trap_helper_p): Properly
            check vector constants for a zero element for integer
            division.  Separate floating point and integer division code.
            Properly handle fixed-point RDIV_EXPR.
    
            * gcc.dg/torture/pr103181.c: New testcase.
            * gcc.dg/pr103248.c: Likewise.
    
    (cherry picked from commit 2f0c8f74daef93c0c7b33294213e7db6df58c4d1)

Diff:
---
 gcc/testsuite/gcc.dg/pr103248.c         |  8 ++++++++
 gcc/testsuite/gcc.dg/torture/pr103181.c | 24 ++++++++++++++++++++++++
 gcc/tree-eh.c                           | 32 +++++++++++++++++++++++++++-----
 3 files changed, 59 insertions(+), 5 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/pr103248.c b/gcc/testsuite/gcc.dg/pr103248.c
new file mode 100644
index 00000000000..da6232d21ee
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr103248.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target fixed_point } */
+/* { dg-options "-fnon-call-exceptions" } */
+
+_Accum sa;
+int c;
+
+void div_csa() { c /= sa; }
diff --git a/gcc/testsuite/gcc.dg/torture/pr103181.c b/gcc/testsuite/gcc.dg/torture/pr103181.c
new file mode 100644
index 00000000000..6bc705ab52e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr103181.c
@@ -0,0 +1,24 @@
+/* { dg-do run } */
+
+typedef unsigned char __attribute__((__vector_size__ (2))) U;
+typedef unsigned short S;
+typedef unsigned int __attribute__((__vector_size__ (64))) V;
+
+V v;
+U a, b, c;
+
+U
+foo (S s)
+{
+  v += __builtin_bswap16 (s) || (S) (a / ((U){3, 0}));
+  return b + c;
+}
+
+int
+main (void)
+{
+  U x = foo (4);
+  if (x[0] || x[1])
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/tree-eh.c b/gcc/tree-eh.c
index 90e335ac74d..3917d00cc9c 100644
--- a/gcc/tree-eh.c
+++ b/gcc/tree-eh.c
@@ -2462,13 +2462,35 @@ operation_could_trap_helper_p (enum tree_code op,
     case FLOOR_MOD_EXPR:
     case ROUND_MOD_EXPR:
     case TRUNC_MOD_EXPR:
-    case RDIV_EXPR:
-      if (honor_snans)
-	return true;
-      if (fp_operation)
-	return flag_trapping_math;
       if (!TREE_CONSTANT (divisor) || integer_zerop (divisor))
         return true;
+      if (TREE_CODE (divisor) == VECTOR_CST)
+	{
+	  /* Inspired by initializer_each_zero_or_onep.  */
+	  unsigned HOST_WIDE_INT nelts = vector_cst_encoded_nelts (divisor);
+	  if (VECTOR_CST_STEPPED_P (divisor)
+	      && !TYPE_VECTOR_SUBPARTS (TREE_TYPE (divisor))
+		    .is_constant (&nelts))
+	    return true;
+	  for (unsigned int i = 0; i < nelts; ++i)
+	    {
+	      tree elt = vector_cst_elt (divisor, i);
+	      if (integer_zerop (elt))
+		return true;
+	    }
+	}
+      return false;
+
+    case RDIV_EXPR:
+      if (fp_operation)
+	{
+	  if (honor_snans)
+	    return true;
+	  return flag_trapping_math;
+	}
+      /* Fixed point operations also use RDIV_EXPR.  */
+      if (!TREE_CONSTANT (divisor) || fixed_zerop (divisor))
+	return true;
       return false;
 
     case LT_EXPR: