[patch, fortran]

[Thomas Koenig <tkoenig@netcologne.de>]

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Hello world,

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

	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.

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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)

[-- Attachment #3: trim_optimize_7.f90 --]
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! { 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" } }