This fixes a predcom ICE where it commons a combination of two
loads but with the combination being conditionally executed.
It's not prepared to handle this situation, disabled with
the following.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to
trunk and 4.8 branch for now.
Richard.
2013-11-19 Richard Biener <rguent...@suse.de>
PR tree-optimization/57517
* tree-predcom.c (combinable_refs_p): Verify the combination
is always executed when the refs are.
* gfortran.fortran-torture/compile/pr57517.f90: New testcase.
* gcc.dg/torture/pr57517.c: Likewise.
Index: gcc/tree-predcom.c
===================================================================
*** gcc/tree-predcom.c (revision 204948)
--- gcc/tree-predcom.c (working copy)
*************** combinable_refs_p (dref r1, dref r2,
*** 2068,2074 ****
stmt = find_common_use_stmt (&name1, &name2);
! if (!stmt)
return false;
acode = gimple_assign_rhs_code (stmt);
--- 2068,2078 ----
stmt = find_common_use_stmt (&name1, &name2);
! if (!stmt
! /* A simple post-dominance check - make sure the combination
! is executed under the same condition as the references. */
! || (gimple_bb (stmt) != gimple_bb (r1->stmt)
! && gimple_bb (stmt) != gimple_bb (r2->stmt)))
return false;
acode = gimple_assign_rhs_code (stmt);
Index: gcc/testsuite/gfortran.fortran-torture/compile/pr57517.f90
===================================================================
*** gcc/testsuite/gfortran.fortran-torture/compile/pr57517.f90 (revision 0)
--- gcc/testsuite/gfortran.fortran-torture/compile/pr57517.f90 (working copy)
***************
*** 0 ****
--- 1,13 ----
+ SUBROUTINE cal_helicity (uh, ph, phb, wavg, ims, ime, its, ite)
+ INTEGER, INTENT( IN ) :: ims, ime, its, ite
+ REAL, DIMENSION( ims:ime), INTENT( IN ) :: ph, phb, wavg
+ REAL, DIMENSION( ims:ime), INTENT( INOUT ) :: uh
+ INTEGER :: i
+ REAL :: zu
+ DO i = its, ite
+ zu = (ph(i ) + phb(i)) + (ph(i-1) + phb(i-1))
+ IF (wavg(i) .GT. 0) THEN
+ uh(i) = uh(i) + zu
+ ENDIF
+ END DO
+ END SUBROUTINE cal_helicity
Index: gcc/testsuite/gcc.dg/torture/pr57517.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr57517.c (revision 0)
--- gcc/testsuite/gcc.dg/torture/pr57517.c (working copy)
***************
*** 0 ****
--- 1,16 ----
+ /* { dg-do compile } */
+
+ int x[1024], y[1024], z[1024], w[1024];
+ void foo (void)
+ {
+ int i;
+ for (i = 1; i < 1024; ++i)
+ {
+ int a = x[i];
+ int b = y[i];
+ int c = x[i-1];
+ int d = y[i-1];
+ if (w[i])
+ z[i] = (a + b) + (c + d);
+ }
+ }
