tree-optimization/116585 - SSA corruption with split_constant_offset

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)

diff --git a/gcc/testsuite/gcc.dg/torture/pr116585.c b/gcc/testsuite/gcc.dg/torture/pr116585.c
new file mode 100644 (file)
index 0000000..108c481
--- /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 706a49f226ed4a84b5e994cc9525ded1d23ae5d2..b7bca6a9d06412504c709f53e44c85e5cbb4f736 100644 (file)
--- a/gcc/tree-data-ref.cc
+++ b/gcc/tree-data-ref.cc
@@ -761,6 +761,14 @@ 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:
@@ -853,9 +861,6 @@ 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;