[PATCH] Fix gimple-loop-interchange ICE (PR tree-optimization/88964)

[Richard Biener]

On Tue, 22 Jan 2019, Jakub Jelinek wrote:

> Hi!
> 
> SCEV can analyze not just integral/pointer IVs, but (scalar) float ones as
> well.  Calling build_int_cst on such types results in ICE, build_zero_cst
> works.  Though the loop invariant PHI IVs, if we represent them as using
> +0.0 step, aren't correct if honoring signed zeros, as + 0.0 will make
> a +0.0 out of -0.0.
> 
> Bootstrapped/regtested on {x86_64,i686,powerpc64{,le}}-linux, ok for trunk?

OK.

Richard.

> 2019-01-22  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR tree-optimization/88964
> 	* gimple-loop-interchange.cc (loop_cand::analyze_induction_var): Use
> 	build_zero_cst instead of build_int_cst.  Return false for loop
> 	invariants which honor signed zeros.
> 
> 	* gfortran.dg/pr88964.f90: New test.
> 
> --- gcc/gimple-loop-interchange.cc.jj	2019-01-01 12:37:17.416970701 +0100
> +++ gcc/gimple-loop-interchange.cc	2019-01-22 11:34:42.303796570 +0100
> @@ -688,11 +688,16 @@ loop_cand::analyze_induction_var (tree v
>    /* Var is loop invariant, though it's unlikely to happen.  */
>    if (tree_does_not_contain_chrecs (chrec))
>      {
> +      /* Punt on floating point invariants if honoring signed zeros,
> +	 representing that as + 0.0 would change the result if init
> +	 is -0.0.  */
> +      if (HONOR_SIGNED_ZEROS (chrec))
> +	return false;
>        struct induction *iv = XCNEW (struct induction);
>        iv->var = var;
>        iv->init_val = init;
>        iv->init_expr = chrec;
> -      iv->step = build_int_cst (TREE_TYPE (chrec), 0);
> +      iv->step = build_zero_cst (TREE_TYPE (chrec));
>        m_inductions.safe_push (iv);
>        return true;
>      }
> --- gcc/testsuite/gfortran.dg/pr88964.f90.jj	2019-01-22 11:54:46.046154065 +0100
> +++ gcc/testsuite/gfortran.dg/pr88964.f90	2019-01-22 11:54:23.172526590 +0100
> @@ -0,0 +1,57 @@
> +! PR tree-optimization/88964
> +! { dg-do compile }
> +! { dg-options "-O3 -fno-tree-forwprop --param sccvn-max-alias-queries-per-access=1" }
> +
> +MODULE pr88964
> +  INTEGER, PARAMETER :: dp=8
> +  REAL(KIND=dp) :: p, q, o
> +CONTAINS
> +  SUBROUTINE foo(a,b,c,f,h)
> +    IMPLICIT NONE
> +    INTEGER :: a, b, c
> +    REAL(KIND=dp) :: f(b*c), h(a*c)
> +    CALL bar(h)
> +    CALL baz(f)
> +    CALL qux(h)
> +  END SUBROUTINE foo
> +  SUBROUTINE bar(h)
> +    IMPLICIT NONE
> +    REAL(KIND=dp) :: h(1*1)
> +    INTEGER :: r, s, t, u
> +    DO u = 1,3
> +      DO t = 1,1
> +        DO s = 1,3
> +          DO r = 1,1
> +            h((t-1)*1+r) = h((t-1)*1+r)-p*o
> +          END DO
> +        END DO
> +      END DO
> +    END DO
> +  END SUBROUTINE bar
> +  SUBROUTINE baz(f)
> +    IMPLICIT NONE
> +    REAL(KIND=dp) :: f(3*1)
> +    INTEGER :: s, t, u
> +    DO u = 1,4
> +      DO t = 1,1
> +        DO s = 1,3
> +          f((t-1)*3+s) = f((t-1)*3+s) - q
> +        END DO
> +      END DO
> +    END DO
> +  END SUBROUTINE baz
> +  SUBROUTINE qux(h)
> +    IMPLICIT NONE
> +    REAL(KIND=dp) :: h(1*1)
> +    INTEGER :: r, s, t, u
> +    DO u = 1,5
> +      DO t = 1,1
> +        DO s = 1,3
> +          DO r = 1,1
> +            h((t-1)*1+r) = h((t-1)*1+r)-p*o
> +          END DO
> +        END DO
> +      END DO
> +    END DO
> +  END SUBROUTINE qux
> +END MODULE pr88964
> 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)