The following extends split_address_to_core_and_offset to handle
POINTER_PLUS_EXPR to be able to simplify
(unsigned long) &MEM[(void *)&D.15512 + 12B] - (unsigned long) ((const int
*) &D.15512 + 4) which appears during niter analysis.
We seem to have various copies of similar code but refactoring didn't
seem appropriate at this stage so I went for the minimal fix.
Bootstrap and regtest running on x86_64-unknown-linux-gnu.
Richard.
2017-04-03 Richard Biener <rguent...@suse.de>
PR tree-optimization/80275
* fold-const.c (split_address_to_core_and_offset): Handle
POINTER_PLUS_EXPR.
* g++.dg/opt/pr80275.C: New testcase.
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c (revision 246642)
+++ gcc/fold-const.c (working copy)
@@ -14341,6 +14341,24 @@ split_address_to_core_and_offset (tree e
&volatilep);
core = build_fold_addr_expr_loc (loc, core);
}
+ else if (TREE_CODE (exp) == POINTER_PLUS_EXPR)
+ {
+ core = TREE_OPERAND (exp, 0);
+ STRIP_NOPS (core);
+ *pbitpos = 0;
+ *poffset = TREE_OPERAND (exp, 1);
+ if (TREE_CODE (*poffset) == INTEGER_CST)
+ {
+ offset_int tem = wi::sext (wi::to_offset (*poffset),
+ TYPE_PRECISION (TREE_TYPE (*poffset)));
+ tem <<= LOG2_BITS_PER_UNIT;
+ if (wi::fits_shwi_p (tem))
+ {
+ *pbitpos = tem.to_shwi ();
+ *poffset = NULL_TREE;
+ }
+ }
+ }
else
{
core = exp;
Index: gcc/testsuite/g++.dg/opt/pr80275.C
===================================================================
--- gcc/testsuite/g++.dg/opt/pr80275.C (nonexistent)
+++ gcc/testsuite/g++.dg/opt/pr80275.C (working copy)
@@ -0,0 +1,16 @@
+// { dg-do compile { target c++14 } }
+// { dg-options "-O2 -fdump-tree-optimized" }
+
+#include <algorithm>
+
+int g()
+{
+ return 1234;
+}
+
+int f2()
+{
+ return std::min({1, g(), 4});
+}
+
+// { dg-final { scan-tree-dump "return 1;" "optimized" } }
