From 19010925aa245590393652fdc72df893ee6245e5 Mon Sep 17 00:00:00 2001
From: Uros Bizjak <ubizjak@gmail.com>
Date: Mon, 7 May 2012 01:07:38 +0200
Subject: [PATCH] i386.md (ctz<mode>2): Emit rep;bsf even for !TARGET_BMI.

	* config/i386/i386.md (ctz<mode>2): Emit rep;bsf even for !TARGET_BMI.
	Emit bsf when optimizing for size.
	(*ffs<mode>_1): Ditto.


Co-Authored-By: Paolo Bonzini <bonzini@gnu.org>

From-SVN: r187219
---
 gcc/ChangeLog           |  7 +++++++
 gcc/config/i386/i386.md | 30 +++++++++++++++++++++++++-----
 2 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index aa909e35208..bba151a7f77 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2012-05-07  Uros Bizjak  <ubizjak@gmail.com>
+	    Paolo Bonzini  <bonzini@gnu.org>
+
+	* config/i386/i386.md (ctz<mode>2): Emit rep;bsf even for !TARGET_BMI.
+	Emit bsf when optimizing for size.
+	(*ffs<mode>_1): Ditto.
+
 2012-05-07  Oleg Endo  <olegendo@gcc.gnu.org>
 
 	PR target/53250
diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 360bd32b9ab..b78054fd549 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -12112,9 +12112,22 @@
    (set (match_operand:SWI48 0 "register_operand" "=r")
 	(ctz:SWI48 (match_dup 1)))]
   ""
-  "bsf{<imodesuffix>}\t{%1, %0|%0, %1}"
+{
+  if (optimize_function_for_size_p (cfun))
+    return "bsf{<imodesuffix>}\t{%1, %0|%0, %1}";
+  else if (TARGET_BMI)
+    return "tzcnt{<imodesuffix>}\t{%1, %0|%0, %1}";
+  else 
+    /* tzcnt expands to rep;bsf and we can use it even if !TARGET_BMI.  */
+    return "rep; bsf{<imodesuffix>}\t{%1, %0|%0, %1}";
+}
   [(set_attr "type" "alu1")
    (set_attr "prefix_0f" "1")
+   (set (attr "prefix_rep")
+     (if_then_else
+       (match_test "optimize_function_for_size_p (cfun)")
+       (const_string "0")
+       (const_string "1")))
    (set_attr "mode" "<MODE>")])
 
 (define_insn "ctz<mode>2"
@@ -12123,14 +12136,21 @@
    (clobber (reg:CC FLAGS_REG))]
   ""
 {
-  if (TARGET_BMI)
-    return "tzcnt{<imodesuffix>}\t{%1, %0|%0, %1}";
-  else
+  if (optimize_function_for_size_p (cfun))
     return "bsf{<imodesuffix>}\t{%1, %0|%0, %1}";
+  else if (TARGET_BMI)
+    return "tzcnt{<imodesuffix>}\t{%1, %0|%0, %1}";
+  else 
+    /* tzcnt expands to rep;bsf and we can use it even if !TARGET_BMI.  */
+    return "rep; bsf{<imodesuffix>}\t{%1, %0|%0, %1}";
 }
   [(set_attr "type" "alu1")
    (set_attr "prefix_0f" "1")
-   (set (attr "prefix_rep") (symbol_ref "TARGET_BMI"))
+   (set (attr "prefix_rep")
+     (if_then_else
+       (match_test "optimize_function_for_size_p (cfun)")
+       (const_string "0")
+       (const_string "1")))
    (set_attr "mode" "<MODE>")])
 
 (define_expand "clz<mode>2"
-- 
2.30.2