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? 2019-01-22 Jakub Jelinek <ja...@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