Hi!
The following testcase ICEs, because copyprop_hardreg_forward_1 decides
to DCE asm goto with REG_UNUSED notes (because the output is unused and
asm isn't volatile). But that DCE just removes the asm goto, leaving
a bb with two successors and no insn at the end that would allow that.
The following patch makes sure we drop that way only INSNs and not
JUMP_INSNs or CALL_INSNs.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2021-05-18 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/100590
* regcprop.c (copyprop_hardreg_forward_1): Only DCE dead sets if
they are NONJUMP_INSN_P.
* gcc.dg/pr100590.c: New test.
--- gcc/regcprop.c.jj 2021-05-15 10:12:04.000000000 +0200
+++ gcc/regcprop.c 2021-05-17 20:38:26.993109935 +0200
@@ -808,6 +808,7 @@ copyprop_hardreg_forward_1 (basic_block
/* Detect obviously dead sets (via REG_UNUSED notes) and remove them. */
if (set
&& !RTX_FRAME_RELATED_P (insn)
+ && NONJUMP_INSN_P (insn)
&& !may_trap_p (set)
&& find_reg_note (insn, REG_UNUSED, SET_DEST (set))
&& !side_effects_p (SET_SRC (set))
--- gcc/testsuite/gcc.dg/pr100590.c.jj 2021-05-17 20:43:37.261699508 +0200
+++ gcc/testsuite/gcc.dg/pr100590.c 2021-05-17 20:43:12.988966308 +0200
@@ -0,0 +1,13 @@
+/* PR rtl-optimization/100590 */
+/* { dg-do compile } */
+/* { dg-options "-O1 -fno-dce -w" } */
+
+int
+foo (void)
+{
+ int x;
+ asm goto ("" : "+r" (x) : : : lab);
+ return 0;
+ lab:
+ return 1;
+}
Jakub
