The following patch fixes
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61215
The patch was bootstrapped on x86/x86-64 and arm and tested on
x86/x86-64.
Unfortunately I did not managed to decrease the test significantly to
include it into the testsuite.
Committed as rev. 210828 into the trunk and rev. 210829 into the
gcc-4.9 branch.
2014-05-22 Vladimir Makarov <vmaka...@redhat.com>
PR rtl-optimization/61215
* lra-elelimination.c (lra_eliminate_regs_1): Don't use
simplify_gen_subreg until final substitution.
Index: lra-eliminations.c
===================================================================
--- lra-eliminations.c (revision 210728)
+++ lra-eliminations.c (working copy)
@@ -565,6 +565,16 @@
alter_subreg (&x, false);
return x;
}
+ else if (! subst_p)
+ {
+ /* LRA can transform subregs itself. So don't call
+ simplify_gen_subreg until LRA transformations are
+ finished. Function simplify_gen_subreg can do
+ non-trivial transformations (like truncation) which
+ might make LRA work to fail. */
+ SUBREG_REG (x) = new_rtx;
+ return x;
+ }
else
return simplify_gen_subreg (GET_MODE (x), new_rtx,
GET_MODE (new_rtx), SUBREG_BYTE (x));
