From ebf7747dbe0204a930815200b3cbc63a09967bf9 Mon Sep 17 00:00:00 2001
From: "Paul E. Murphy" <murp@ibm.com>
Date: Fri, 29 Mar 2024 16:11:36 -0500
Subject: cmd/internal/obj/ppc64: on Power10, use xxspltidp for float constants

Any normal float32 constant can be generated by this instruction;
use xxspltidp when possible. This prefixed instruction is much
faster than the two instruction load sequence from the
float32/float64 constant pool.

Change-Id: Id751d9ffdae71463adbde66427b986f0b2ef74c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/575555
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Paul Murphy <murp@ibm.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
---
 test/codegen/floats.go | 31 +++++++++++++++++++++++++++++++
 test/codegen/math.go   |  4 +++-
 2 files changed, 34 insertions(+), 1 deletion(-)

(limited to 'test')

diff --git a/test/codegen/floats.go b/test/codegen/floats.go
index d5c5475567..baa745bdee 100644
--- a/test/codegen/floats.go
+++ b/test/codegen/floats.go
@@ -196,3 +196,34 @@ func Float32Max(a, b float32) float32 {
 	// ppc64/power10:"XSMAXJDP"
 	return max(a, b)
 }
+
+// ------------------------ //
+//  Constant Optimizations  //
+// ------------------------ //
+
+func Float32Constant() float32 {
+	// ppc64x/power8:"FMOVS\t[$]f32\\.42440000\\(SB\\)"
+	// ppc64x/power9:"FMOVS\t[$]f32\\.42440000\\(SB\\)"
+	// ppc64x/power10:"XXSPLTIDP\t[$]1111752704,"
+	return 49.0
+}
+
+func Float64Constant() float64 {
+	// ppc64x/power8:"FMOVD\t[$]f64\\.4048800000000000\\(SB\\)"
+	// ppc64x/power9:"FMOVD\t[$]f64\\.4048800000000000\\(SB\\)"
+	// ppc64x/power10:"XXSPLTIDP\t[$]1111752704,"
+	return 49.0
+}
+
+func Float32DenormalConstant() float32 {
+	// ppc64x:"FMOVS\t[$]f32\\.00400000\\(SB\\)"
+	return 0x1p-127
+}
+
+// A float64 constant which can be exactly represented as a
+// denormal float32 value. On ppc64x, denormal values cannot
+// be used with XXSPLTIDP.
+func Float64DenormalFloat32Constant() float64 {
+	// ppc64x:"FMOVD\t[$]f64\\.3800000000000000\\(SB\\)"
+	return 0x1p-127
+}
diff --git a/test/codegen/math.go b/test/codegen/math.go
index 331ebbe609..eb6e927dec 100644
--- a/test/codegen/math.go
+++ b/test/codegen/math.go
@@ -204,7 +204,9 @@ func constantCheck32() bool {
 func constantConvert32(x float32) float32 {
 	// amd64:"MOVSS\t[$]f32.3f800000\\(SB\\)"
 	// s390x:"FMOVS\t[$]f32.3f800000\\(SB\\)"
-	// ppc64x:"FMOVS\t[$]f32.3f800000\\(SB\\)"
+	// ppc64x/power8:"FMOVS\t[$]f32.3f800000\\(SB\\)"
+	// ppc64x/power9:"FMOVS\t[$]f32.3f800000\\(SB\\)"
+	// ppc64x/power10:"XXSPLTIDP\t[$]1065353216, VS0"
 	// arm64:"FMOVS\t[$]\\(1.0\\)"
 	if x > math.Float32frombits(0x3f800000) {
 		return -x
-- 
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