From: Jakub Jelinek <jakub@redhat.com>
To: Richard Biener <rguenther@suse.de>, Jeff Law <law@redhat.com>
Cc: gcc-patches@gcc.gnu.org
Subject: [PATCH] Fix ICE with widen_mult and -ftrapv (PR tree-optimization/83523)
Date: Thu, 21 Dec 2017 17:54:00 -0000 [thread overview]
Message-ID: <20171221175451.GB2353@tucnak> (raw)
Hi!
Converting widening mult, or widen_{plus,minus}_expr, or integral mult to
fma is IMNSHO undesirable with -ftrapv for signed types - the expansion of
those doesn't detect overflows and by giving up we don't need to worry about
formerly trapping MULT_EXPR becoming something that isn't trapping and
performing EH cleanups etc.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2017-12-21 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/83523
* tree-ssa-math-opts.c (is_widening_mult_p): Return false if
for INTEGER_TYPE TYPE_OVERFLOW_TRAPS.
(convert_mult_to_fma): Likewise.
* g++.dg/tree-ssa/pr83523.C: New test.
--- gcc/tree-ssa-math-opts.c.jj 2017-12-21 09:43:19.000000000 +0100
+++ gcc/tree-ssa-math-opts.c 2017-12-21 12:22:10.576488270 +0100
@@ -2196,8 +2196,12 @@ is_widening_mult_p (gimple *stmt,
{
tree type = TREE_TYPE (gimple_assign_lhs (stmt));
- if (TREE_CODE (type) != INTEGER_TYPE
- && TREE_CODE (type) != FIXED_POINT_TYPE)
+ if (TREE_CODE (type) == INTEGER_TYPE)
+ {
+ if (TYPE_OVERFLOW_TRAPS (type))
+ return false;
+ }
+ else if (TREE_CODE (type) != FIXED_POINT_TYPE)
return false;
if (!is_widening_mult_rhs_p (type, gimple_assign_rhs1 (stmt), type1_out,
@@ -2656,7 +2660,7 @@ convert_mult_to_fma (gimple *mul_stmt, t
/* We don't want to do bitfield reduction ops. */
if (INTEGRAL_TYPE_P (type)
- && !type_has_mode_precision_p (type))
+ && (!type_has_mode_precision_p (type) || TYPE_OVERFLOW_TRAPS (type)))
return false;
/* If the target doesn't support it, don't generate it. We assume that
--- gcc/testsuite/g++.dg/tree-ssa/pr83523.C.jj 2017-12-21 12:20:56.555403891 +0100
+++ gcc/testsuite/g++.dg/tree-ssa/pr83523.C 2017-12-21 12:20:02.000000000 +0100
@@ -0,0 +1,25 @@
+// PR tree-optimization/83523
+// { dg-do compile }
+// { dg-options "-O2 -fexceptions -fnon-call-exceptions -ftrapv" }
+
+#ifdef __SIZEOF_INT128__
+typedef __int128 T;
+typedef long long int U;
+#else
+typedef long long int T;
+typedef int U;
+#endif
+
+struct S { S (); ~S (); };
+void bar ();
+
+T
+foo (U x, U y)
+{
+ T z = x;
+ S s;
+ bar ();
+ z *= y;
+ bar ();
+ return z;
+}
Jakub
next reply other threads:[~2017-12-21 17:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-21 17:54 Jakub Jelinek [this message]
2017-12-21 18:57 ` Richard Biener
2017-12-21 23:09 ` Jeff Law
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