From: Hans-Peter Nilsson <hp@axis.com>
Date: Mon, 27 Jan 2020 23:59:41 +0000 (+0100)
Subject: cris.md: Post-reload, split/generate clobberless zero source moves
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=12bdaa7d3e94cf30f8ce1750325a245175bdbee5;p=gcc.git

cris.md: Post-reload, split/generate clobberless zero source moves

A separated follow-up to the previous change: Also emit moves
from zero as not clobbering condition-codes.

(note: actually folded into the previous ChangeLog-entry)
gcc:
	* config/cris/cris.md ("movsi"): For a zero-source post-reload,
	generate a clobberless variant.
	("*mov_fromzero<mode>_split"): New split.
	("*mov_fromzero<mode>"): New insn.
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6234bd71bdb..b6f7d46adeb 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -43,11 +43,14 @@
 	* config/cris/cris.h (REVERSIBLE_CC_MODE): Define to true.
 
 	* config/cris/cris.md ("movsi"): For memory destination
-	post-reload, generate clobberless variant.
+	post-reload, generate clobberless variant.  Similarly for a
+	zero-source post-reload.
 	("*mov_tomem<mode>_split"): New split.
 	("*mov_tomem<mode>"): New insn.
 	("enabled", mov_tomem_enabled): Define and use to exclude "x" ->
 	"Q>m" for less-than-SImode.
+	("*mov_fromzero<mode>_split"): New split.
+	("*mov_fromzero<mode>"): New insn.
 
 2020-05-08  Vladimir Makarov  <vmakarov@redhat.com>
 
diff --git a/gcc/config/cris/cris.md b/gcc/config/cris/cris.md
index 3de2f5a136f..bf2cf966387 100644
--- a/gcc/config/cris/cris.md
+++ b/gcc/config/cris/cris.md
@@ -449,8 +449,9 @@
 
    /* At post-reload time, we'll get here for e.g. split multi-mode insns
       with a memory destination.  Go directly to the clobber-less variant.
-      FIXME: Also applies to zero source.  */
-   if (MEM_P (operands[0]) && reload_completed)
+      FIXME: Also applies to special-register source or destination.  */
+   if (reload_completed
+       && (MEM_P (operands[0]) || operands[1] == const0_rtx))
      {
         emit_insn (gen_rtx_SET (operands[0], operands[1]));
         DONE;
@@ -697,6 +698,20 @@
    move %1,%0"
   [(set_attr "slottable" "yes,yes,yes,no,no,no")
    (set_attr "enabled" "<mov_tomem_enabled>")])
+
+(define_split ;; "*mov_fromzero<mode>_split"
+  [(set (match_operand:BWD 0 "register_operand") (const_int 0))
+   (clobber (reg:CC CRIS_CC0_REGNUM))]
+  "reload_completed
+   && REGNO(operands[0]) <= CRIS_LAST_GENERAL_REGISTER"
+  [(set (match_dup 0) (const_int 0))]
+  "")
+
+(define_insn "*mov_fromzero<mode>"
+  [(set (match_operand:BWD 0 "register_operand" "=r") (const_int 0))]
+  "reload_completed"
+  "clear<m> %0"
+  [(set_attr "slottable" "yes")])
 
 ;; Movem patterns.  Primarily for use in function prologue and epilogue.
 ;; Unfortunately, movem stores R0 in the highest memory location, thus