PDP11: Use `const_double_zero' to express double zero constant

We do not define a comparison operation between floating-point and
integer data, including integer zero constant.  Consequently the RTL
instruction stream presented to the post-reload comparison elimination
pass will include, where applicable, floating-point comparison insns
against `const_double:DF 0.0 [0x0.0p+0]' rather than `const_int 0 [0]',
meaning that the latter expression will not match when used in machine
description.

Use `const_double_zero' then for the relevant patterns to match the
intended RTL instructions.

	gcc/
	* config/pdp11/pdp11.md (fcc_cc, fcc_ccnz): Use
	`const_double_zero' to express double zero constant.

diff --git a/gcc/config/pdp11/pdp11.md b/gcc/config/pdp11/pdp11.md
index 7a4d50f..cdef49f 100644 (file)
--- a/gcc/config/pdp11/pdp11.md
+++ b/gcc/config/pdp11/pdp11.md
@@ -105,7 +105,7 @@
    (clobber (reg FCC_REGNUM))]
   ""
   [(set (reg:CC FCC_REGNUM)
-       (compare:CC (match_dup 1) (const_int 0)))
+       (compare:CC (match_dup 1) (const_double_zero)))
    (set (match_dup 0) (match_dup 1))])
 
 (define_subst "fcc_ccnz"
@@ -113,7 +113,7 @@
    (clobber (reg FCC_REGNUM))]
   ""
   [(set (reg:CCNZ FCC_REGNUM)
-       (compare:CCNZ (match_dup 1) (const_int 0)))
+       (compare:CCNZ (match_dup 1) (const_double_zero)))
    (set (match_dup 0) (match_dup 1))])
 
 (define_subst_attr "cc_cc" "cc_cc" "_nocc" "_cc")