From 87acfc36194e3101b8ebcc599a78e2481224922d Mon Sep 17 00:00:00 2001
From: Xi Ruoyao <xry111@xry111.site>
Date: Sat, 30 Dec 2023 21:40:11 +0800
Subject: [PATCH] LoongArch: Provide fmin/fmax RTL pattern for vectors

We already had smin/smax RTL pattern using vfmin/vfmax instructions.
But for smin/smax, it's unspecified what will happen if either operand
contains any NaN operands.  So we would not vectorize the loop with
-fno-finite-math-only (the default for all optimization levels expect
-Ofast).

But, LoongArch vfmin/vfmax instruction is IEEE-754-2008 conformant so we
can also use them and vectorize the loop.

gcc/ChangeLog:

	* config/loongarch/simd.md (fmax<mode>3): New define_insn.
	(fmin<mode>3): Likewise.
	(reduc_fmax_scal_<mode>3): New define_expand.
	(reduc_fmin_scal_<mode>3): Likewise.

gcc/testsuite/ChangeLog:

	* gcc.target/loongarch/vfmax-vfmin.c: New test.
---
 gcc/config/loongarch/simd.md                  | 31 +++++++++++++++++++
 .../gcc.target/loongarch/vfmax-vfmin.c        | 31 +++++++++++++++++++
 2 files changed, 62 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/loongarch/vfmax-vfmin.c

diff --git a/gcc/config/loongarch/simd.md b/gcc/config/loongarch/simd.md
index 93fb39abcf5b..8ac1d75a85cb 100644
--- a/gcc/config/loongarch/simd.md
+++ b/gcc/config/loongarch/simd.md
@@ -426,6 +426,37 @@
   [(set_attr "type" "simd_fcmp")
    (set_attr "mode" "<MODE>")])
 
+; [x]vf{min/max} instructions are IEEE-754-2008 conforming, use them for
+; the corresponding IEEE-754-2008 operations.  We must use UNSPEC instead
+; of smin/smax though, see PR105414 and PR107013.
+
+(define_int_iterator UNSPEC_FMAXMIN [UNSPEC_FMAX UNSPEC_FMIN])
+(define_int_attr fmaxmin [(UNSPEC_FMAX "fmax") (UNSPEC_FMIN "fmin")])
+
+(define_insn "<fmaxmin><mode>3"
+  [(set (match_operand:FVEC 0 "register_operand" "=f")
+	(unspec:FVEC [(match_operand:FVEC 1 "register_operand" "f")
+		      (match_operand:FVEC 2 "register_operand" "f")]
+		     UNSPEC_FMAXMIN))]
+  ""
+  "<x>v<fmaxmin>.<simdfmt>\t%<wu>0,%<wu>1,%<wu>2"
+  [(set_attr "type" "simd_fminmax")
+   (set_attr "mode" "<MODE>")])
+
+;; ... and also reduc operations.
+(define_expand "reduc_<fmaxmin>_scal_<mode>"
+  [(match_operand:<UNITMODE> 0 "register_operand")
+   (match_operand:FVEC 1 "register_operand")
+   (const_int UNSPEC_FMAXMIN)]
+  ""
+{
+  rtx tmp = gen_reg_rtx (<MODE>mode);
+  loongarch_expand_vector_reduc (gen_<fmaxmin><mode>3, tmp, operands[1]);
+  emit_insn (gen_vec_extract<mode><unitmode> (operands[0], tmp,
+					      const0_rtx));
+  DONE;
+})
+
 ; The LoongArch SX Instructions.
 (include "lsx.md")
 
diff --git a/gcc/testsuite/gcc.target/loongarch/vfmax-vfmin.c b/gcc/testsuite/gcc.target/loongarch/vfmax-vfmin.c
new file mode 100644
index 000000000000..811fee361c33
--- /dev/null
+++ b/gcc/testsuite/gcc.target/loongarch/vfmax-vfmin.c
@@ -0,0 +1,31 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mtune=la464 -mlasx" } */
+/* { dg-final { scan-assembler "\tvfmin\\.d" } } */
+/* { dg-final { scan-assembler "\tvfmax\\.d" } } */
+/* { dg-final { scan-assembler "\txvfmin\\.d" } } */
+/* { dg-final { scan-assembler "\txvfmax\\.d" } } */
+/* { dg-final { scan-assembler "\tvfmin\\.s" } } */
+/* { dg-final { scan-assembler "\tvfmax\\.s" } } */
+/* { dg-final { scan-assembler "\txvfmin\\.s" } } */
+/* { dg-final { scan-assembler "\txvfmax\\.s" } } */
+
+#define T(OP) __typeof__ (__builtin_##OP (0, 0))
+
+#define TEST(OP, LEN) \
+void \
+test_##OP##LEN (T (OP) *restrict dest, \
+		const T (OP) *restrict src1, \
+		const T (OP) *restrict src2) \
+{ \
+  for (int i = 0; i < LEN / sizeof (T(OP)); i++) \
+    dest[i] = __builtin_##OP (src1[i], src2[i]); \
+}
+
+TEST(fmin, 16)
+TEST(fmax, 16)
+TEST(fmin, 32)
+TEST(fmax, 32)
+TEST(fminf, 16)
+TEST(fmaxf, 16)
+TEST(fminf, 32)
+TEST(fmaxf, 32)