lra: Clobbers in a parallel are earlyclobbers (PR83245)

The documentation (rtl.texi) says:

  When a @code{clobber} expression for a register appears inside a
  @code{parallel} with other side effects, the register allocator
  guarantees that the register is unoccupied both before and after that
  insn if it is a hard register clobber.

and at least the rs6000 backend relies on that (see PR83245).  This
patch restores that behaviour.

Registers that are also used as operands in the instruction are not
treated as earlyclobber, so such insns also still work (PR80818, an
s390 testcase).

	PR rtl-optimization/83245
	* lra.c (collect_non_operand_hard_regs): Treat clobbers of non-operand
	hard registers as earlyclobber, also if not in an asm.

From-SVN: r255377

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 95496132a2bcfd6c868551a3d9034ca03844bf03..3b0f55ffe26ecc37ec466989732996269afdf32a 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2017-12-04  Segher Boessenkool  <segher@kernel.crashing.org>
+
+       PR rtl-optimization/83245
+       * lra.c (collect_non_operand_hard_regs): Treat clobbers of non-operand
+       hard registers as earlyclobber, also if not in an asm.
+
 2017-12-04  Segher Boessenkool  <segher@kernel.crashing.org>
 
        PR bootstrap/83265

diff --git a/gcc/lra.c b/gcc/lra.c
index f49c50a40362655431393190b059ade94ac5a2aa..0d76eac3f3b5bcbba8194c86da7ee495efc635f0 100644 (file)
--- a/gcc/lra.c
+++ b/gcc/lra.c
@@ -888,14 +888,10 @@ collect_non_operand_hard_regs (rtx_insn *insn, rtx *x,
                                            list, OP_IN, false);
       break;
     case CLOBBER:
-      {
-       int code = INSN_CODE (insn);
-       /* We treat clobber of non-operand hard registers as early
-          clobber (the behavior is expected from asm).  */
-       list = collect_non_operand_hard_regs (insn, &XEXP (op, 0), data,
-                                             list, OP_OUT, code < 0);
-       break;
-      }
+      /* We treat clobber of non-operand hard registers as early clobber.  */
+      list = collect_non_operand_hard_regs (insn, &XEXP (op, 0), data,
+                                           list, OP_OUT, true);
+      break;
     case PRE_INC: case PRE_DEC: case POST_INC: case POST_DEC:
       list = collect_non_operand_hard_regs (insn, &XEXP (op, 0), data,
                                            list, OP_INOUT, false);