PATCH: Fix Java compilation crash

Thu May 16 10:05:00 GMT 2002

The Java compiler was crashing on this test case:
 public class Y {
 static double d2 = 0.0;
 static Object lockObject = new Object();
 public static double f(double d1) {
 synchronized (lockObject){
 d2 = Math.max(d1, d2);
 }
 return d2;
 }
 }
when compiling with -O2 on i686-pc-linux-gnu. The reason is that we
had a JUMP_INSN with an outgoing REG_EH edge that we were throwing
away in purge_dead_edges.
Bootstrapped and tested on i686-pc-linux-gnu.
This is a regression from GCC 3.0, so I commited this patch on the
branch. On the mainline, the test case does not crash, but so far
as I can tell that is only because the compiler generates slightly
different RTL. So, I've checked in the patch on the mainline too.
Java people, I have no idea how to add a Java regression test. You
might want to take this test case and stick it in the testsuite
somewhere...
--
Mark Mitchell mark@codesourcery.com
CodeSourcery, LLC http://www.codesourcery.com
2002年05月16日 Mark Mitchell <mark@codesourcery.com>
	* cfgrtl.c (purge_dead_edges): Correct handling of EDGE_EH.
Index: cfgrtl.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cfgrtl.c,v
retrieving revision 1.29.2.4
diff -c -p -r1.29.2.4 cfgrtl.c
*** cfgrtl.c	9 Apr 2002 20:38:56 -0000	1.29.2.4
--- cfgrtl.c	16 May 2002 16:45:34 -0000
*************** purge_dead_edges (bb)
*** 1954,1970 ****
 	 e->flags &= ~EDGE_ABNORMAL;
! 	 /* Check purposes we can have edge. */
! 	 if ((e->flags & EDGE_FALLTHRU)
! 	 && any_condjump_p (insn))
 	 continue;
 	 else if (e->dest != EXIT_BLOCK_PTR
 		 && e->dest->head == JUMP_LABEL (insn))
 	 continue;
! 	 else if (e->dest == EXIT_BLOCK_PTR
! 		 && returnjump_p (insn))
 	 continue;
 	 purged = true;
 	 remove_edge (e);
 	}
--- 1954,1979 ----
 	 e->flags &= ~EDGE_ABNORMAL;
! 	 /* See if this edge is one we should keep. */
! 	 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
! 	 /* A conditional jump can fall through into the next
! 	 block, so we should keep the edge. */
 	 continue;
 	 else if (e->dest != EXIT_BLOCK_PTR
 		 && e->dest->head == JUMP_LABEL (insn))
+ 	 /* If the destination block is the target of the jump,
+ 	 keep the edge. */
 	 continue;
! 	 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
! 	 /* If the destination block is the exit block, and this
! 	 instruction is a return, then keep the edge. */
! 	 continue;
! 	 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
! 	 /* Keep the edges that correspond to exceptions thrown by
! 	 this instruction. */
 	 continue;
+ 	 /* We do not need this edge. */
 	 purged = true;
 	 remove_edge (e);
 	}