[gcc/devel/omp/gcc-12] amdgcn: add fmin/fmax patterns

[Andrew Stubbs <ams@gcc.gnu.org>]

https://gcc.gnu.org/g:d8f1377233fcacd2034e6c59a8745c54c7656d32

commit d8f1377233fcacd2034e6c59a8745c54c7656d32
Author: Andrew Stubbs <ams@codesourcery.com>
Date:   Fri Oct 28 13:09:20 2022 +0100

    amdgcn: add fmin/fmax patterns
    
    Add fmin/fmax for scalar, vector, and reductions.  The smin/smax patterns are
    already using the IEEE compliant hardware instructions anyway, so we can just
    expand to use those insns.
    
    gcc/ChangeLog:
    
            * config/gcn/gcn-valu.md (fminmaxop): New iterator.
            (<fexpander><mode>3): New define_expand.
            (<fexpander><mode>3<exec>): Likewise.
            (reduc_<fexpander>_scal_<mode>): Likewise.
            * config/gcn/gcn.md (fexpander): New attribute.
    
    (cherry picked from commit 10aa0356118f44e5f4d720a2a4c731b173baa298)

Diff:
---
 gcc/ChangeLog.omp          | 11 +++++++++++
 gcc/config/gcn/gcn-valu.md | 28 ++++++++++++++++++++++++++++
 gcc/config/gcn/gcn.md      |  4 ++++
 3 files changed, 43 insertions(+)

diff --git a/gcc/ChangeLog.omp b/gcc/ChangeLog.omp
index 6c7cf8a4dae..f8d5af30ca5 100644
--- a/gcc/ChangeLog.omp
+++ b/gcc/ChangeLog.omp
@@ -1,3 +1,14 @@
+2022-11-01  Andrew Stubbs  <ams@codesourcery.com>
+
+	Backport from mainline:
+	2022-10-31  Andrew Stubbs  <ams@codesourcery.com>
+
+	* config/gcn/gcn-valu.md (fminmaxop): New iterator.
+	(<fexpander><mode>3): New define_expand.
+	(<fexpander><mode>3<exec>): Likewise.
+	(reduc_<fexpander>_scal_<mode>): Likewise.
+	* config/gcn/gcn.md (fexpander): New attribute.
+
 2022-11-01  Andrew Stubbs  <ams@codesourcery.com>
 
 	Backport from mainline:
diff --git a/gcc/config/gcn/gcn-valu.md b/gcc/config/gcn/gcn-valu.md
index 8b113ca7f91..d224f87cfb1 100644
--- a/gcc/config/gcn/gcn-valu.md
+++ b/gcc/config/gcn/gcn-valu.md
@@ -2469,6 +2469,23 @@
   [(set_attr "type" "vop2")
    (set_attr "length" "8,8")])
 
+(define_code_iterator fminmaxop [smin smax])
+(define_expand "<fexpander><mode>3"
+  [(set (match_operand:FP 0 "gcn_valu_dst_operand")
+	(fminmaxop:FP
+	  (match_operand:FP 1 "gcn_valu_src0_operand")
+	  (match_operand:FP 2 "gcn_valu_src1_operand")))]
+  ""
+  {})
+
+(define_expand "<fexpander><mode>3<exec>"
+  [(set (match_operand:V_FP 0 "gcn_valu_dst_operand")
+	(fminmaxop:V_FP
+	  (match_operand:V_FP 1 "gcn_valu_src0_operand")
+	  (match_operand:V_FP 2 "gcn_valu_src1_operand")))]
+  ""
+  {})
+
 ;; }}}
 ;; {{{ FP unops
 
@@ -3533,6 +3550,17 @@
     DONE;
   })
 
+(define_expand "reduc_<fexpander>_scal_<mode>"
+  [(match_operand:<SCALAR_MODE> 0 "register_operand")
+   (fminmaxop:V_FP
+     (match_operand:V_FP 1 "register_operand"))]
+  ""
+  {
+    /* fmin/fmax are identical to smin/smax.  */
+    emit_insn (gen_reduc_<expander>_scal_<mode> (operands[0], operands[1]));
+    DONE;
+  })
+
 ;; Warning: This "-ffast-math" implementation converts in-order reductions
 ;;          into associative reductions. It's also used where OpenMP or
 ;;          OpenACC paralellization has already broken the in-order semantics.
diff --git a/gcc/config/gcn/gcn.md b/gcc/config/gcn/gcn.md
index 1ac0ad0d818..da617cb19ad 100644
--- a/gcc/config/gcn/gcn.md
+++ b/gcc/config/gcn/gcn.md
@@ -379,6 +379,10 @@
    (sign_extend "extend")
    (zero_extend "zero_extend")])
 
+(define_code_attr fexpander
+  [(smin "fmin")
+   (smax "fmax")])
+
 ;; }}}
 ;; {{{ Miscellaneous instructions