[PATCH][Backport][GCC13] tree-optimization/116585 - SSA corruption with split_constant_offset

[Qing Zhao]

From: Richard Biener <rguent...@suse.de>

Hi, this is the backport of the fix for PR116585 to GCC13.
bootstrapped and regress tested on both X86 and aarch64.

Okay for committing?

thanks.

Qing.

=======
split_constant_offset when looking through SSA defs can end up
picking SSA leafs that are subject to abnormal coalescing.  This
can lead to downstream consumers to insert code based on the
result (like from dataref analysis) in places that violate constraints
for abnormal coalescing.  It's best to not expand defs whose operands
are subject to abnormal coalescing - and not either do something when
a subexpression has operands like that already.

        PR tree-optimization/116585
        * tree-data-ref.cc (split_constant_offset_1): When either
        operand is subject to abnormal coalescing do no further
        processing.

        * gcc.dg/torture/pr116585.c: New testcase.

(cherry picked from commit 1d0cb3b5fca69b81e69cfdb4aea0eebc1ac04750)
---
 gcc/testsuite/gcc.dg/torture/pr116585.c | 32 +++++++++++++++++++++++++
 gcc/tree-data-ref.cc                    | 11 ++++++---
 2 files changed, 40 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/torture/pr116585.c

diff --git a/gcc/testsuite/gcc.dg/torture/pr116585.c 
b/gcc/testsuite/gcc.dg/torture/pr116585.c
new file mode 100644
index 00000000000..108c481e104
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr116585.c
@@ -0,0 +1,32 @@
+/* { dg-do compile } */
+
+char *s1, *s2;
+extern int* my_alloc (int);
+extern int _setjmp ();
+extern void bar();
+void foo(int s1len, int s2len)
+{
+  int e;
+  e = _setjmp ();
+    {
+      int l, i;
+      int *md = my_alloc(((sizeof(int)) * (s1len + 1) * (s2len)));
+      s1len++;
+      for (; s1len; l)
+       for (; s2len; l)
+         for (; s1len; i)
+           {
+             int j = 1;
+             for (; j < s2len; j++)
+               {
+                 int cost;
+                 if (s1[1] == s2[1])
+                   cost = 0;
+                 else
+                   cost = 1;
+                 md[j * s1len ] = ((cost));
+               }
+           }
+      bar();
+    }
+}
diff --git a/gcc/tree-data-ref.cc b/gcc/tree-data-ref.cc
index 96934addff1..7657eeaf9e6 100644
--- a/gcc/tree-data-ref.cc
+++ b/gcc/tree-data-ref.cc
@@ -763,6 +763,14 @@ split_constant_offset_1 (tree type, tree op0, enum 
tree_code code, tree op1,
   if (INTEGRAL_TYPE_P (type) && TYPE_OVERFLOW_TRAPS (type))
     return false;
 
+  if (TREE_CODE (op0) == SSA_NAME
+      && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op0))
+    return false;
+  if (op1
+      && TREE_CODE (op1) == SSA_NAME
+      && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op1))
+    return false;
+
   switch (code)
     {
     case INTEGER_CST:
@@ -855,9 +863,6 @@ split_constant_offset_1 (tree type, tree op0, enum 
tree_code code, tree op1,
 
     case SSA_NAME:
       {
-       if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op0))
-         return false;
-
        gimple *def_stmt = SSA_NAME_DEF_STMT (op0);
        enum tree_code subcode;
 
-- 
2.31.1