[gcc r12-5395] middle-end/103248 - fix RDIV_EXPR handling with fixed point

[gcc r12-5395] middle-end/103248 - fix RDIV_EXPR handling with fixed point

[Richard Biener]

https://gcc.gnu.org/g:fb15abdc9b61a0b7fa24a37f85d19dc449cfd5bf

commit r12-5395-gfb15abdc9b61a0b7fa24a37f85d19dc449cfd5bf
Author: Richard Biener <rguenther@suse.de>
Date:   Tue Nov 16 11:47:26 2021 +0100

    middle-end/103248 - fix RDIV_EXPR handling with fixed point
    
    This fixes the previous 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.
    
    2021-11-16  Richard Biener  <rguenther@suse.de>
    
            PR middle-end/103248
            * tree-eh.c (operation_could_trap_helper_p): Properly handle
            fixed-point RDIV_EXPR.
    
            * gcc.dg/pr103248.c: New testcase.

Diff:
---
 gcc/testsuite/gcc.dg/pr103248.c |  8 ++++++++
 gcc/tree-eh.c                   | 12 +++++++++---
 2 files changed, 17 insertions(+), 3 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/tree-eh.c b/gcc/tree-eh.c
index 3eff07fc8fe..916da85af2e 100644
--- a/gcc/tree-eh.c
+++ b/gcc/tree-eh.c
@@ -2474,10 +2474,16 @@ operation_could_trap_helper_p (enum tree_code op,
       return false;
 
     case RDIV_EXPR:
-      if (honor_snans)
+      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;
-      gcc_assert (fp_operation);
-      return flag_trapping_math;
+      return false;
 
     case LT_EXPR:
     case LE_EXPR: