Hi!
We ICE on the following testcase, because handle_cast was incorrectly
testing !m_first to see whether it should use m_data[m_bitfld_load + 1]
or fresh SSA_NAME for a PHI result.
Now, m_first is in the routine sometimes temporarily cleared in between
doing prepare_data_in_out and the !m_first check and only before returning
restored from the save_first copy.
Without this patch, we try to use the same SSA_NAME (_12 here) in 2
different PHI results which is obviously invalid IL and ICEs very quickly.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2024-03-23 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/114433
* gimple-lower-bitint.cc (bitint_large_huge::handle_cast): For
m_bitfld_load check save_first rather than m_first.
* gcc.dg/torture/bitint-68.c: New test.
--- gcc/gimple-lower-bitint.cc.jj 2024-03-22 14:54:41.767972684 +0100
+++ gcc/gimple-lower-bitint.cc 2024-03-22 17:13:43.702249666 +0100
@@ -1506,7 +1506,7 @@ bitint_large_huge::handle_cast (tree lhs
if (m_bitfld_load)
{
tree t4;
- if (!m_first)
+ if (!save_first)
t4 = m_data[m_bitfld_load + 1];
else
t4 = make_ssa_name (m_limb_type);
--- gcc/testsuite/gcc.dg/torture/bitint-68.c.jj 2024-03-22 17:26:29.841713520
+0100
+++ gcc/testsuite/gcc.dg/torture/bitint-68.c 2024-03-22 17:26:51.941409603
+0100
@@ -0,0 +1,28 @@
+/* PR tree-optimization/114433 */
+/* { dg-do run { target bitint } } */
+/* { dg-options "-std=c23" } */
+/* { dg-skip-if "" { ! run_expensive_tests } { "*" } { "-O0" "-O2" } } */
+/* { dg-skip-if "" { ! run_expensive_tests } { "-flto" } { "" } } */
+
+#if __BITINT_MAXWIDTH__ >= 511
+struct S { int : 31; _BitInt(511) b : 300; } s;
+
+__attribute__((noipa)) _BitInt(511)
+foo (void)
+{
+ return s.b << 1;
+}
+#endif
+
+int
+main ()
+{
+#if __BITINT_MAXWIDTH__ >= 511
+ s.b =
642460398785925402356009598661384732715767737595497615767135001949421105426024498988100867wb;
+ if (foo () != ((_BitInt(511))
642460398785925402356009598661384732715767737595497615767135001949421105426024498988100867wb)
<< 1)
+ __builtin_abort ();
+ s.b =
2655156766298562299560755420298083843774074962786295887660222690220887wb;
+ if (foo () != ((_BitInt(511))
2655156766298562299560755420298083843774074962786295887660222690220887wb) << 1)
+ __builtin_abort ();
+#endif
+}
Jakub
