[ARM][PATCH, PR 68223] arm_[su]min_cmp pattern fails

[Michael Collison]

The patterns arm_smin_cmp and arm_umin_cmp patterns fail if operand 0 
and operand 2 are equal and both are less than operand 1. The solution 
is to remove the two patterns.


2015-11-06  Michael Collison  

PR target/68223
* gcc/config/arm/arm.md (*arm_smin_cmp): Remove pattern.
(*arm_umin_cmp): Likewise.
* gcc.target/arm/mincmp.c: Remove testcase.

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

diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
index 02e147e..6ba1ec3 100644
--- a/gcc/config/arm/arm.md
+++ b/gcc/config/arm/arm.md
@@ -3455,44 +3455,6 @@
(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
deleted file mode 100644
index ade3bd9..000
--- a/gcc/testsuite/gcc.target/arm/mincmp.c
+++ /dev/null
@@ -1,20 +0,0 @@
-/* { 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)
-{
-  return i < (min (x, y));
-}
-
-int 
-bar (int i, int x, int y)
-{
-  return i < (min (x, y));
-}
-
-/* { dg-final { scan-assembler "cmpcs" } } */
-/* { dg-final { scan-assembler "cmpge" } } */
-- 
1.9.1

Re: [ARM][PATCH, PR 68223] arm_[su]min_cmp pattern fails

[Ramana Radhakrishnan]

On 06/11/15 06:46, Michael Collison wrote:
> The patterns arm_smin_cmp and arm_umin_cmp patterns fail if operand 0 and 
> operand 2 are equal and both are less than operand 1. The solution is to 
> remove the two patterns.

Agreed. There is no way this can be made to work without additional branches 
and that means the original pattern is probably more efficient.

> 
> 2015-11-06  Michael Collison   Ramana Radhakrishnan 
> 
> PR target/68223

   
Instead just say .. (watching out formatting in the Changelog).

Revert:
2015-08-01  Michael Collison  

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

I would like to have a simple execution test added as a follow-up and not rely 
on a test failing in BE testing to show this failure up.

You do not need approval to revert your own patch unless you see that it's 
become enmeshed with other people's work - So, this is OK assuming no 
regressions.

regards
Ramana