RE: [PATCH]middle-end cse: Make sure duplicate elements are not entered into the equivalence set [PR103404]

[Tamar Christina via Gcc-patches]

Hi,

As discussed off-line this can only happen with a V1 mode, so here's a much 
simpler patch.

Bootstrapped Regtested on aarch64-none-linux-gnu,
x86_64-pc-linux-gnu and no regressions.


Ok for master?

Thanks,
Tamar

gcc/ChangeLog:

        PR rtl-optimization/103404
        * cse.c (find_sets_in_insn): Don't select elements out of a V1 mode
        subreg.

gcc/testsuite/ChangeLog:

        PR rtl-optimization/103404
        * gcc.target/i386/pr103404.c: New test.

--- inline copy of patch ---

diff --git a/gcc/cse.c b/gcc/cse.c
index 
c1c7d0ca27b73c4b944b4719f95fece74e0358d5..dc5d5aed047c7776f44b159a4286390d6499c18d
 100644
--- a/gcc/cse.c
+++ b/gcc/cse.c
@@ -4275,7 +4275,12 @@ find_sets_in_insn (rtx_insn *insn, vec<struct set> 
*psets)
       else if (GET_CODE (SET_SRC (x)) == CALL)
        ;
       else if (GET_CODE (SET_SRC (x)) == CONST_VECTOR
-              && GET_MODE_CLASS (GET_MODE (SET_SRC (x))) != MODE_VECTOR_BOOL)
+              && GET_MODE_CLASS (GET_MODE (SET_SRC (x))) != MODE_VECTOR_BOOL
+              /* Prevent duplicates from being generated if the type is a V1
+                 type and a subreg.  Folding this will result in the same
+                 element as folding x itself.  */
+              && !(SUBREG_P (SET_DEST (x))
+                   && known_eq (GET_MODE_NUNITS (GET_MODE (SET_SRC (x))), 1)))
        {
          /* First register the vector itself.  */
          add_to_set (psets, x);
diff --git a/gcc/testsuite/gcc.target/i386/pr103404.c 
b/gcc/testsuite/gcc.target/i386/pr103404.c
new file mode 100644
index 
0000000000000000000000000000000000000000..66f33645301db09503fc0977fd0f061a19e56ea5
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr103404.c
@@ -0,0 +1,32 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-Og -fcse-follow-jumps -fno-dce 
-fno-early-inlining -fgcse -fharden-conditional-branches -frerun-cse-after-loop 
-fno-tree-ccp -mavx5124fmaps -std=c99 -w" } */
+
+typedef unsigned __attribute__((__vector_size__ (4))) U;
+typedef unsigned __attribute__((__vector_size__ (16))) V;
+typedef unsigned __attribute__((__vector_size__ (64))) W;
+
+int x, y;
+
+V v;
+W w;
+
+inline
+int bar (U a)
+{
+  a |= x;
+  W k =
+    __builtin_shufflevector (v, 5 / a,
+                            2, 4, 0, 2, 4, 1, 0, 1,
+                            1, 2, 1, 3, 0, 4, 4, 0);
+  w = k;
+  y = 0;
+}
+
+int
+foo ()
+{
+  bar ((U){0xffffffff});
+  for (unsigned i; i < sizeof (foo);)
+    ;
+}
+

rb15109.patch
Description: rb15109.patch