[gcc r13-720] rs6000: Skip debug insns for union [PR105627]

[Kewen Lin <linkw@gcc.gnu.org>]

https://gcc.gnu.org/g:149d04ccbb908b3a251485b43faf204752942b9f

commit r13-720-g149d04ccbb908b3a251485b43faf204752942b9f
Author: Kewen Lin <linkw@linux.ibm.com>
Date:   Tue May 24 01:00:22 2022 -0500

    rs6000: Skip debug insns for union [PR105627]
    
    As PR105627 exposes, pass analyze_swaps should skip debug
    insn when doing unionfind_union.  One debug insn can use
    several pseudos, if we take debug insn into account, we can
    union those insns defining them and generate some unexpected
    unions.
    
    Based on the assumption that it's impossible to have one
    pseudo which is defined by one debug insn but is used by one
    nondebug insn, we just asserts debug insn never shows up in
    function union_defs.
    
            PR target/105627
    
    gcc/ChangeLog:
    
            * config/rs6000/rs6000-p8swap.cc (union_defs): Assert def_insn can't
            be a debug insn.
            (union_uses): Skip debug use_insn.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/powerpc/pr105627.c: New test.

Diff:
---
 gcc/config/rs6000/rs6000-p8swap.cc          | 10 ++++++----
 gcc/testsuite/gcc.target/powerpc/pr105627.c | 26 ++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/gcc/config/rs6000/rs6000-p8swap.cc b/gcc/config/rs6000/rs6000-p8swap.cc
index d301bc3fe59..275702fee1b 100644
--- a/gcc/config/rs6000/rs6000-p8swap.cc
+++ b/gcc/config/rs6000/rs6000-p8swap.cc
@@ -214,8 +214,9 @@ union_defs (swap_web_entry *insn_entry, rtx insn, df_ref use)
       if (DF_REF_INSN_INFO (link->ref))
 	{
 	  rtx def_insn = DF_REF_INSN (link->ref);
-	  (void)unionfind_union (insn_entry + INSN_UID (insn),
-				 insn_entry + INSN_UID (def_insn));
+	  gcc_assert (NONDEBUG_INSN_P (def_insn));
+	  unionfind_union (insn_entry + INSN_UID (insn),
+			   insn_entry + INSN_UID (def_insn));
 	}
 
       link = link->next;
@@ -242,8 +243,9 @@ union_uses (swap_web_entry *insn_entry, rtx insn, df_ref def)
       if (DF_REF_INSN_INFO (link->ref))
 	{
 	  rtx use_insn = DF_REF_INSN (link->ref);
-	  (void)unionfind_union (insn_entry + INSN_UID (insn),
-				 insn_entry + INSN_UID (use_insn));
+	  if (NONDEBUG_INSN_P (use_insn))
+	    unionfind_union (insn_entry + INSN_UID (insn),
+			     insn_entry + INSN_UID (use_insn));
 	}
 
       link = link->next;
diff --git a/gcc/testsuite/gcc.target/powerpc/pr105627.c b/gcc/testsuite/gcc.target/powerpc/pr105627.c
new file mode 100644
index 00000000000..bafb31ff061
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr105627.c
@@ -0,0 +1,26 @@
+/* Specify -w to disable some warnings, such as: -Wpsabi.  */
+/* { dg-options "-Og -fcompare-debug -mdejagnu-cpu=power8 -w" } */
+
+typedef unsigned char __attribute__ ((__vector_size__ (8))) U;
+typedef unsigned char __attribute__ ((__vector_size__ (64))) V;
+
+U u;
+char c;
+V v;
+
+V
+foo (void)
+{
+  V w = c
+	& __builtin_shufflevector (u, (V){0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+					  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+					  0, 0, 0, 0, 0, 0, 0, 5},
+				   24, 24, 41, 45, 53, 60, 22, 35, 45, 12, 61,
+				   9, 52, 15, 44, 46, 5, 5, 1, 0, 4, 9, 0, 8, 5,
+				   7, 2, 5, 9, 2, 7, 7, 5, 6, 0, 2, 6, 1, 7, 7,
+				   0, 4, 0, 1, 7, 2, 5, 3, 2, 3, 5, 6, 6, 6, 0,
+				   6, 1, 9, 0, 5, 4, 3, 5, 4);
+  w = w + v;
+  return w;
+}
+