The following should fix PR37242.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2019-08-20 Richard Biener <rguent...@suse.de>
PR tree-optimization/37242
* tree-ssa-sccvn.c (visit_nary_op): Also CSE (T)(a + b)
to (T)a + (T)b if we know that a + b does not overflow.
* gcc.dg/tree-ssa/ssa-fre-80.c: New testcase.
Index: gcc/tree-ssa-sccvn.c
===================================================================
--- gcc/tree-ssa-sccvn.c (revision 274672)
+++ gcc/tree-ssa-sccvn.c (working copy)
@@ -4312,8 +4312,12 @@ visit_nary_op (tree lhs, gassign *stmt)
operation. */
if (INTEGRAL_TYPE_P (type)
&& TREE_CODE (rhs1) == SSA_NAME
- /* We only handle sign-changes or zero-extension -> & mask. */
- && ((TYPE_UNSIGNED (TREE_TYPE (rhs1))
+ /* We only handle sign-changes, zero-extension -> & mask or
+ sign-extension if we know the inner operation doesn't
+ overflow. */
+ && (((TYPE_UNSIGNED (TREE_TYPE (rhs1))
+ || (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
+ && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (rhs1))))
&& TYPE_PRECISION (type) > TYPE_PRECISION (TREE_TYPE (rhs1)))
|| TYPE_PRECISION (type) == TYPE_PRECISION (TREE_TYPE (rhs1))))
{
@@ -4347,7 +4351,9 @@ visit_nary_op (tree lhs, gassign *stmt)
{
unsigned lhs_prec = TYPE_PRECISION (type);
unsigned rhs_prec = TYPE_PRECISION (TREE_TYPE (rhs1));
- if (lhs_prec == rhs_prec)
+ if (lhs_prec == rhs_prec
+ || (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
+ && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (rhs1))))
{
gimple_match_op match_op (gimple_match_cond::UNCOND,
NOP_EXPR, type, ops[0]);
Index: gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-80.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-80.c (nonexistent)
+++ gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-80.c (working copy)
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-fre1" } */
+
+unsigned long a, b;
+void foo (int m, int f)
+{
+ unsigned long tem = (unsigned long)m;
+ a = tem + 1;
+ if (f)
+ {
+ int tem2 = m + 1;
+ b = (unsigned long)tem2; /* Eliminated to a. */
+ }
+}
+
+/* { dg-final { scan-tree-dump-times "\\(long unsigned int\\)" 1 "fre1" } } */
