diff mbox

Fix PR80275

Message ID alpine.LSU.2.20.1704031114210.30715@zhemvz.fhfr.qr
State New
Headers show

Commit Message

Richard Biener April 3, 2017, 9:16 a.m. UTC 
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  <rguenther@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.
diff mbox

Patch

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" } }