SCEV analysis requires us to be in loop-closed SSA form to be able
to compute overall effects of inner loops when required. Unfortunately
we have too many places it is used where we are not in loop-closed SSA
form. The following patch makes us more conservative in two places
where we previously ICEd.
I'm not 100% sure we'll get away w/ not being in loop-closed SSA form
(code correctness wise) but unless we get a testcase showing this the
following is a sane approach (esp. on release branches).
Bootstrap and regtest in progress on x86_64-unknown-linux-gnu.
Richard.
2017-04-27 Richard Biener <rguent...@suse.de>
PR middle-end/80539
* tree-chrec.c (chrec_fold_plus_poly_poly): Deal with not
being in loop-closed SSA form conservatively.
(chrec_fold_multiply_poly_poly): Likewise.
* gcc.dg/torture/pr80539.c: New testcase.
Index: gcc/tree-chrec.c
===================================================================
--- gcc/tree-chrec.c (revision 247293)
+++ gcc/tree-chrec.c (working copy)
@@ -149,7 +149,12 @@ chrec_fold_plus_poly_poly (enum tree_cod
/* This function should never be called for chrecs of loops that
do not belong to the same loop nest. */
- gcc_assert (loop0 == loop1);
+ if (loop0 != loop1)
+ {
+ /* It still can happen if we are not in loop-closed SSA form. */
+ gcc_assert (! loops_state_satisfies_p (LOOP_CLOSED_SSA));
+ return chrec_dont_know;
+ }
if (code == PLUS_EXPR || code == POINTER_PLUS_EXPR)
{
@@ -211,7 +216,12 @@ chrec_fold_multiply_poly_poly (tree type
chrec_fold_multiply (type, CHREC_LEFT (poly0), poly1),
CHREC_RIGHT (poly0));
- gcc_assert (loop0 == loop1);
+ if (loop0 != loop1)
+ {
+ /* It still can happen if we are not in loop-closed SSA form. */
+ gcc_assert (! loops_state_satisfies_p (LOOP_CLOSED_SSA));
+ return chrec_dont_know;
+ }
/* poly0 and poly1 are two polynomials in the same variable,
{a, +, b}_x * {c, +, d}_x -> {a*c, +, a*d + b*c + b*d, +, 2*b*d}_x. */
Index: gcc/testsuite/gcc.dg/torture/pr80539.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr80539.c (nonexistent)
+++ gcc/testsuite/gcc.dg/torture/pr80539.c (working copy)
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+
+signed char a, b;
+void fn1()
+{
+ signed char c, e;
+ short d;
+ if (0) {
+ for (; d;) {
+l1:
+ for (c = 7; a; c++)
+ ;
+ e = 6;
+ for (; b; e++)
+ ;
+ }
+ c -= e;
+ }
+ if (d == 7)
+ goto l1;
+ a = c;
+}
