* toplev.c (no_new_pseudos): Define.

        (rest_of_compilation):  Set no_new_pseudos as needed.
        * emit-rtl.c (gen_reg_rtx): Abort if we try to create a new pseudo
        if no_new_pseudos is set.
        * rtl.h (no_new_pseudos): Declare it.
        * reload1.c (reload): Update comments.
        * md.texi: Corresponding changes.
        * reload1.c (reg_used_in_insn): Renamed from reg_used_by_pseudo.
        (choose_reload_regs): Rename it here as well.  When computing it,
        also merge in used hardregs.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@23855 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 8 insertions, 2 deletions

diff --git a/gcc/md.texi b/gcc/md.texi
index f3f6cd6a3aa..6177ac2b55c 100644
--- a/gcc/md.texi
+++ b/gcc/md.texi
@@ -1746,14 +1746,20 @@ pseudo registers that did not get hard registers, while on other
 machines explicit memory references will get optional reloads.
 
 If a scratch register is required to move an object to or from memory,
-it can be allocated using @code{gen_reg_rtx} prior to reload.  But this
-is impossible during and after reload.  If there are cases needing
+it can be allocated using @code{gen_reg_rtx} prior to life analysis.
+
+If there are cases needing
 scratch registers after reload, you must define
 @code{SECONDARY_INPUT_RELOAD_CLASS} and perhaps also
 @code{SECONDARY_OUTPUT_RELOAD_CLASS} to detect them, and provide
 patterns @samp{reload_in@var{m}} or @samp{reload_out@var{m}} to handle
 them.  @xref{Register Classes}.
 
+@findex no_new_pseudos
+The global variable @code{no_new_pseudos} can be used to determine if it
+is unsafe to create new pseudo registers.  If this variable is nonzero, then
+it is unsafe to call @code{gen_reg_rtx} to allocate a new pseudo.
+
 The constraints on a @samp{mov@var{m}} must permit moving any hard
 register to any other hard register provided that
 @code{HARD_REGNO_MODE_OK} permits mode @var{m} in both registers and