Re: [ARM] Optimize compare against smin/umin

[Kyrill Tkachov]

Hi Michael,

On 26/07/15 23:54, Michael Collison wrote:

Here is an updated patch that addresses the issues you mentioned:

2015-07-24  Michael Collison  <michael.colli...@linaro.org
                      Ramana Radhakrishnan <ramana.radhakrish...@arm.com>

                * gcc/config/arm/arm.md (*arm_smin_cmp): New pattern.
                (*arm_umin_cmp): Likewise.
                * gcc.target/arm/mincmp.c: Test min compare idiom.

Just "New test." would be a better ChangeLog entry for this.

diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
index 0be70a8..361c292 100644
--- a/gcc/config/arm/arm.md
+++ b/gcc/config/arm/arm.md
@@ -3455,6 +3455,44 @@
      (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"
+  "#"
+  "&& reload_completed"
+  [(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_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"
+  "#"
+  "&& reload_completed"
+  [(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_expand "umaxsi3"
     [(parallel [
       (set (match_operand:SI 0 "s_register_operand" "")
diff --git a/gcc/testsuite/gcc.target/arm/mincmp.c
b/gcc/testsuite/gcc.target/arm/mincmp.c
new file mode 100644
index 0000000..2a55c6d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/mincmp.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-require-effective-target arm32 } */
+
+#define min(x, y) ((x) <= (y)) ? (x) : (y)
+
+unsigned int foo (unsigned int i, unsigned int x ,unsigned int y)

Comma after "unsigned int x" in the wrong place.

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

Can you please use GNU style for the testcase.
New line after return type, function name an arguments on their own line.

Ok with these changes.

Thanks,
Kyrill