From patchwork Mon Jun  6 19:24:50 2011
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Subject: [fortran] Some more TRIM optimizations
Date: Mon, 06 Jun 2011 09:24:50 -0000
From: Thomas Koenig <tkoenig@netcologne.de>
X-Patchwork-Id: 99012
Message-Id: <4DED2982.2060802@netcologne.de>
To: "fortran@gcc.gnu.org" <fortran@gcc.gnu.org>,
 gcc-patches <gcc-patches@gcc.gnu.org>

I wrote:

> Hello world,
>
> the attached patch extends removing trailing TRIMs in assignments for
> cases like a // trim(b). Regression-tested. OK for trunk?
>
> Thomas

This time with the test case corrected (cleanup of the *.original file)
and a more meaningful Subject line.

OK?

	Thomas

2011-05-06  Thomas König  <tkoenig@gcc.gnu.org>

         * frontend-passes.c (optimize_assignment): Follow chains
         of concatenation operators to the end for removing trailing
         TRIMS for assignments.

2011-05-06  Thomas König  <tkoenig@gcc.gnu.org>

         * gfortran.dg/trim_optimize_7.f90:  New test.
! { dg-do run }
! { dg-options "-O -fdump-tree-original" }
! Check that trailing trims are also removed from assignment of
! expressions involving concatenations of strings .
program main
  character(2) :: a,b,c
  character(8) :: d
  a = 'a '
  b = 'b '
  c = 'c '
  d = a // b // a // trim(c)   ! This should be optimized away.
  if (d /= 'a b a c ') call abort
  d = a // trim(b) // c // a   ! This shouldn't.
  if (d /= 'a bc a  ') call abort
  d = a // b // a // trim(trim(c)) ! This should also be optimized away.
  if (d /= 'a b a c ') call abort
end
! { dg-final { scan-tree-dump-times "string_len_trim" 1 "original" } }
! { dg-final { cleanup-tree-dump "original" } }


Index: frontend-passes.c
===================================================================
--- frontend-passes.c	(Revision 174391)
+++ frontend-passes.c	(Arbeitskopie)
@@ -500,6 +500,14 @@ optimize_assignment (gfc_code * c)
 
   if (lhs->ts.type == BT_CHARACTER)
     {
+      /* Check for a // b // trim(c).  Looping is probably not
+	 necessary because the parser usually generates
+	 (// (// a b ) trim(c) ) , but better safe than sorry.  */
+
+      while (rhs->expr_type == EXPR_OP
+	     && rhs->value.op.op == INTRINSIC_CONCAT)
+	rhs = rhs->value.op.op2;
+
       if (rhs->expr_type == EXPR_FUNCTION &&
 	  rhs->value.function.isym &&
 	  rhs->value.function.isym->id == GFC_ISYM_TRIM)