[gcc r11-8488] regcprop: Avoid DCE of asm goto [PR100590]

[gcc r11-8488] regcprop: Avoid DCE of asm goto [PR100590]

[Jakub Jelinek]

https://gcc.gnu.org/g:490ffb47ad10df1793c4894c7c888d7a10576f1a

commit r11-8488-g490ffb47ad10df1793c4894c7c888d7a10576f1a
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue May 18 10:26:45 2021 +0200

    regcprop: Avoid DCE of asm goto [PR100590]
    
    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.
    
    2021-05-18  Jakub Jelinek  <jakub@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.
    
    (cherry picked from commit c81704b359283bb54696755ead881ab04136da94)

Diff:
---
 gcc/regcprop.c                  |  1 +
 gcc/testsuite/gcc.dg/pr100590.c | 13 +++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/gcc/regcprop.c b/gcc/regcprop.c
index 7c271e22f47..44f6295b516 100644
--- a/gcc/regcprop.c
+++ b/gcc/regcprop.c
@@ -808,6 +808,7 @@ copyprop_hardreg_forward_1 (basic_block bb, struct value_data *vd)
       /* 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))
diff --git a/gcc/testsuite/gcc.dg/pr100590.c b/gcc/testsuite/gcc.dg/pr100590.c
new file mode 100644
index 00000000000..5cd36877fa1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr100590.c
@@ -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;
+}