The following patch fixes
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67609
The patch was bootstrapped and tested on x86/x86-64, arm, aarch64.
It was also tested on ppc64 (unfortunately bootstrap with LRA is broken
now).
Committed as rev. 229087.
Index: ChangeLog
===================================================================
--- ChangeLog (revision 228844)
+++ ChangeLog (working copy)
@@ -1,3 +1,9 @@
+2015-10-20 Vladimir Makarov <vmaka...@redhat.com>
+
+ PR rtl-optimization/67609
+ * lra-splill.c (lra_final_code_change): Don't remove all
+ sub-registers.
+
2015-10-15 Marek Polacek <pola...@redhat.com>
* tree-ssa-reassoc.c (attempt_builtin_copysign): Call
Index: testsuite/ChangeLog
===================================================================
--- testsuite/ChangeLog (revision 228844)
+++ testsuite/ChangeLog (working copy)
@@ -1,3 +1,8 @@
+2015-10-20 Vladimir Makarov <vmaka...@redhat.com>
+
+ PR rtl-optimization/67609
+ * gcc.target/i386/pr67609.c: New.
+
2015-10-15 Marek Polacek <pola...@redhat.com>
* gcc.dg/tree-ssa/reassoc-42.c: New test.
Index: lra-spills.c
===================================================================
--- lra-spills.c (revision 228844)
+++ lra-spills.c (working copy)
@@ -727,14 +727,44 @@ lra_final_code_change (void)
lra_insn_recog_data_t id = lra_get_insn_recog_data (insn);
struct lra_static_insn_data *static_id = id->insn_static_data;
bool insn_change_p = false;
-
- for (i = id->insn_static_data->n_operands - 1; i >= 0; i--)
- if ((DEBUG_INSN_P (insn) || ! static_id->operand[i].is_operator)
- && alter_subregs (id->operand_loc[i], ! DEBUG_INSN_P (insn)))
- {
- lra_update_dup (id, i);
- insn_change_p = true;
- }
+
+ for (i = id->insn_static_data->n_operands - 1; i >= 0; i--)
+ {
+ if (! DEBUG_INSN_P (insn) && static_id->operand[i].is_operator)
+ continue;
+
+ rtx op = *id->operand_loc[i];
+
+ if (static_id->operand[i].type == OP_OUT
+ && GET_CODE (op) == SUBREG && REG_P (SUBREG_REG (op))
+ && ! LRA_SUBREG_P (op))
+ {
+ hard_regno = REGNO (SUBREG_REG (op));
+ /* We can not always remove sub-registers of
+ hard-registers as we may lose information that
+ only a part of registers is changed and
+ subsequent optimizations may do wrong
+ transformations (e.g. dead code eliminations).
+ We can not also keep all sub-registers as the
+ subsequent optimizations can not handle all such
+ cases. Here is a compromise which works. */
+ if ((GET_MODE_SIZE (GET_MODE (op))
+ < GET_MODE_SIZE (GET_MODE (SUBREG_REG (op))))
+ && (hard_regno_nregs[hard_regno][GET_MODE (SUBREG_REG (op))]
+ == hard_regno_nregs[hard_regno][GET_MODE (op)])
+#ifdef STACK_REGS
+ && (hard_regno < FIRST_STACK_REG
+ || hard_regno > LAST_STACK_REG)
+#endif
+ )
+ continue;
+ }
+ if (alter_subregs (id->operand_loc[i], ! DEBUG_INSN_P (insn)))
+ {
+ lra_update_dup (id, i);
+ insn_change_p = true;
+ }
+ }
if (insn_change_p)
lra_update_operator_dups (id);
}
Index: testsuite/gcc.target/i386/pr67609.c
===================================================================
--- testsuite/gcc.target/i386/pr67609.c (revision 0)
+++ testsuite/gcc.target/i386/pr67609.c (working copy)
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -msse2" } */
+/* { dg-require-effective-target lp64 } */
+/* { dg-final { scan-assembler "movdqa" } } */
+
+#include <emmintrin.h>
+__m128d reg;
+void set_lower(double b)
+{
+ double v[2];
+ _mm_store_pd(v, reg);
+ v[0] = b;
+ reg = _mm_load_pd(v);
+}
