alias.c (true_dependence, [...]): A read involving a label_ref or the constant pool doesn't create a dependency.

	* alias.c (true_dependence, write_dependence_p): A read
	involving a label_ref or the constant pool doesn't create
	a dependency.

	* rtl.h (unchanging): Improve documentation.

From-SVN: r35771

1 files changed, 4 insertions, 3 deletions

diff --git a/gcc/rtl.h b/gcc/rtl.h
index 3802f25..a882cf6 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -116,9 +116,10 @@ typedef struct rtx_def
   /* 1 in an INSN if it can call another function.
      LINK_COST_FREE in an INSN_LIST.  */
   unsigned int call : 1;
-  /* 1 in a MEM or REG if value of this expression will never change
-     during the current function, even though it is not
-     manifestly constant.
+  /* 1 in a REG if value of this expression will never change during
+     the current function, even though it is not manifestly constant.
+     1 in a MEM if contents of memory are constant.  This does not
+     necessarily mean that the value of this expression is constant.
      1 in a SUBREG if it is from a promoted variable that is unsigned.
      1 in a SYMBOL_REF if it addresses something in the per-function
      constants pool.