[ARM] Optimize compare against smin/umin

[Michael Collison]

This patch is designed to optimize constructs such as:
#define min(x, y) ((x) <= (y)) ? (x) : (y)

unsignedint  foo (unsignedint  i, unsignedint  x ,unsignedint  y)
{
  return  i < (min (x, y));
}

int  bar (int  i,int  x,int  y)
{
  return  i < (min (x, y));
}

Patch was tested on arm-linux-gnueabi, arm-linux-gnueabihf, 
armeb-linux-gnueabihf. Okay for trunk?


2015-06-24  Michael Collison  <michael.colli...@linaro.org

    2012-05-01  Ramana Radhakrishnan <ramana.radhakrish...@linaro.org>

    * gcc/config/arm/arm.md (*arm_smin_cmp): New pattern.
    (*arm_umin_cmp): Likewise.

diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
index 1ac8af0..994c95f 100644
--- a/gcc/config/arm/arm.md
+++ b/gcc/config/arm/arm.md
@@ -3455,6 +3455,28 @@
    (set_attr "type" "multiple,multiple")]
 )

+;; t = (s/u)min (x, y)
+;; cc = cmp (t, z)
+;; is the same as
+;; cmp x, z
+;; cmpge(u) y, z
+
+(define_insn_and_split "*arm_smin_cmp"
+  [(set (reg:CC CC_REGNUM)
+    (compare:CC
+     (smin:SI (match_operand:SI 0 "s_register_operand" "r")
+          (match_operand:SI 1 "s_register_operand" "r"))
+     (match_operand:SI 2 "s_register_operand" "r")))]
+  "TARGET_32BIT"
+  "#"
+  ""
+  [(set (reg:CC CC_REGNUM)
+    (compare:CC (match_dup 0) (match_dup 2)))
+   (cond_exec (ge:CC (reg:CC CC_REGNUM) (const_int 0))
+          (set (reg:CC CC_REGNUM)
+           (compare:CC (match_dup 1) (match_dup 2))))]
+)
+
 (define_expand "umaxsi3"
   [(parallel [
     (set (match_operand:SI 0 "s_register_operand" "")
@@ -3521,6 +3543,22 @@
    (set_attr "type" "store1")]
 )

+(define_insn_and_split "*arm_umin_cmp"
+  [(set (reg:CC CC_REGNUM)
+    (compare:CC
+     (umin:SI (match_operand:SI 0 "s_register_operand" "r")
+          (match_operand:SI 1 "s_register_operand" "r"))
+     (match_operand:SI 2 "s_register_operand" "r")))]
+  "TARGET_32BIT"
+  "#"
+  ""
+  [(set (reg:CC CC_REGNUM)
+    (compare:CC (match_dup 0) (match_dup 2)))
+   (cond_exec (geu:CC (reg:CC CC_REGNUM) (const_int 0))
+          (set (reg:CC CC_REGNUM)
+           (compare:CC (match_dup 1) (match_dup 2))))]
+)
+
 (define_insn "*store_minmaxsi"
   [(set (match_operand:SI 0 "memory_operand" "=m")
     (match_operator:SI 3 "minmax_operator"

--
Michael Collison
Linaro Toolchain Working Group
michael.colli...@linaro.org