Hi!
The following testcase shows different behavior between -g and -g0
in constprop_register, if a flags register setter is separated
from a conditional jump using those flags with -g by a DEBUG_INSN.
As it uses just NEXT_INSN, for -g it will look at the DEBUG_INSN which is
not a conditional jump, while otherwise it would look at the conditional
jump and call cprop_jump.
Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux,
ok for trunk/11.2/10.4?
2021-04-20 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/100148
* cprop.c (constprop_register): Use next_nondebug_insn instead of
NEXT_INSN.
* g++.dg/opt/pr100148.C: New test.
--- gcc/cprop.c.jj 2021-01-04 10:25:39.000000000 +0100
+++ gcc/cprop.c 2021-04-20 13:48:28.691450016 +0200
@@ -1007,16 +1007,18 @@ static int
constprop_register (rtx from, rtx src, rtx_insn *insn)
{
rtx sset;
+ rtx_insn *next_insn;
/* Check for reg or cc0 setting instructions followed by
conditional branch instructions first. */
if ((sset = single_set (insn)) != NULL
- && NEXT_INSN (insn)
- && any_condjump_p (NEXT_INSN (insn)) && onlyjump_p (NEXT_INSN (insn)))
+ && (next_insn = next_nondebug_insn (insn)) != NULL
+ && any_condjump_p (next_insn)
+ && onlyjump_p (next_insn))
{
rtx dest = SET_DEST (sset);
if ((REG_P (dest) || CC0_P (dest))
- && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn),
+ && cprop_jump (BLOCK_FOR_INSN (insn), insn, next_insn,
from, src))
return 1;
}
--- gcc/testsuite/g++.dg/opt/pr100148.C.jj 2021-04-20 15:32:31.820489909
+0200
+++ gcc/testsuite/g++.dg/opt/pr100148.C 2021-04-20 15:32:06.376770658 +0200
@@ -0,0 +1,27 @@
+// PR rtl-optimization/100148
+// { dg-do compile }
+// { dg-options "-O2 -fno-dce -fno-tree-dce -fno-tree-dominator-opts
-fno-tree-sink -fcompare-debug" }
+
+int i;
+enum E { } e, ee;
+
+bool
+baz (int)
+{
+ return ee;
+}
+
+bool bar ();
+bool a, b;
+
+void
+foo ()
+{
+ switch (ee)
+ {
+ case 0:
+ e = E (a ? : i);
+ case 1:
+ !(b || baz (0) && bar ());
+ }
+}
Jakub
