re PR rtl-optimization/67609 (Generates wrong code for SSE2 _mm_load_pd)

2015-10-20  Vladimir Makarov  <vmakarov@redhat.com>

	PR rtl-optimization/67609
	* lra-splill.c (lra_final_code_change): Don't remove all
	sub-registers.

2015-10-20  Vladimir Makarov  <vmakarov@redhat.com>

	PR rtl-optimization/67609
	* gcc.target/i386/pr67609.c: New.

From-SVN: r229087

gcc/ChangeLog

+2015-10-20  Vladimir Makarov  <vmakarov@redhat.com>
+
+	PR rtl-optimization/67609
+	* lra-splill.c (lra_final_code_change): Don't remove all
+	sub-registers.
+
 2015-10-20  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	* simplify-rtx.c (simplify_binary_operation): If either operand was

gcc/lra-spills.c

@@ -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);
 	}

gcc/testsuite/ChangeLog

+2015-10-20  Vladimir Makarov  <vmakarov@redhat.com>
+
+	PR rtl-optimization/67609
+	* gcc.target/i386/pr67609.c: New.
+
 2015-10-20  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	* gcc.target/aarch64/fmul_fcvt_1.c: Add multiply-by-32 cases.

gcc/testsuite/gcc.target/i386/pr67609.c

+/* { 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);
+}