From 061d77cb7008cf9e4d8b3b6382828b483bff032f Mon Sep 17 00:00:00 2001
From: "Paul E. Murphy" <murp@ibm.com>
Date: Fri, 15 Sep 2023 15:20:56 -0500
Subject: [PATCH] cmd/compile/internal/ssa: on PPC64, generate large constant
 paddi

This is only supported power10/linux/PPC64. This generates smaller,
faster code by merging a pli + add into paddi.

Change-Id: I1f4d522fce53aea4c072713cc119a9e0d7065acc
Reviewed-on: https://go-review.googlesource.com/c/go/+/531717
Run-TryBot: Paul Murphy <murp@ibm.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
---
 .../internal/ssa/_gen/PPC64latelower.rules    |  3 +++
 .../internal/ssa/rewritePPC64latelower.go     | 27 +++++++++++++++++++
 test/codegen/arithmetic.go                    | 15 +++++++++++
 3 files changed, 45 insertions(+)

diff --git a/src/cmd/compile/internal/ssa/_gen/PPC64latelower.rules b/src/cmd/compile/internal/ssa/_gen/PPC64latelower.rules
index 5980fc922e..d5fe1276aa 100644
--- a/src/cmd/compile/internal/ssa/_gen/PPC64latelower.rules
+++ b/src/cmd/compile/internal/ssa/_gen/PPC64latelower.rules
@@ -33,3 +33,6 @@
 
 // Convert rotated 32 bit masks on 32 bit values into rlwinm. In general, this leaves the upper 32 bits in an undefined state.
 (AND <t> x:(MOVDconst [m]) n) && t.Size() == 4 && isPPC64WordRotateMask(m) => (RLWINM [encodePPC64RotateMask(0,m,32)] n)
+
+// When PCRel is supported, paddi can add a 34b signed constant in one instruction.
+(ADD (MOVDconst [m]) x) && supportsPPC64PCRel() && (m<<30)>>30 == m => (ADDconst [m] x)
diff --git a/src/cmd/compile/internal/ssa/rewritePPC64latelower.go b/src/cmd/compile/internal/ssa/rewritePPC64latelower.go
index 8b22a7d02f..2e8ad928f8 100644
--- a/src/cmd/compile/internal/ssa/rewritePPC64latelower.go
+++ b/src/cmd/compile/internal/ssa/rewritePPC64latelower.go
@@ -7,6 +7,8 @@ import "cmd/compile/internal/types"
 
 func rewriteValuePPC64latelower(v *Value) bool {
 	switch v.Op {
+	case OpPPC64ADD:
+		return rewriteValuePPC64latelower_OpPPC64ADD(v)
 	case OpPPC64AND:
 		return rewriteValuePPC64latelower_OpPPC64AND(v)
 	case OpPPC64ISEL:
@@ -22,6 +24,31 @@ func rewriteValuePPC64latelower(v *Value) bool {
 	}
 	return false
 }
+func rewriteValuePPC64latelower_OpPPC64ADD(v *Value) bool {
+	v_1 := v.Args[1]
+	v_0 := v.Args[0]
+	// match: (ADD (MOVDconst [m]) x)
+	// cond: supportsPPC64PCRel() && (m<<30)>>30 == m
+	// result: (ADDconst [m] x)
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpPPC64MOVDconst {
+				continue
+			}
+			m := auxIntToInt64(v_0.AuxInt)
+			x := v_1
+			if !(supportsPPC64PCRel() && (m<<30)>>30 == m) {
+				continue
+			}
+			v.reset(OpPPC64ADDconst)
+			v.AuxInt = int64ToAuxInt(m)
+			v.AddArg(x)
+			return true
+		}
+		break
+	}
+	return false
+}
 func rewriteValuePPC64latelower_OpPPC64AND(v *Value) bool {
 	v_1 := v.Args[1]
 	v_0 := v.Args[0]
diff --git a/test/codegen/arithmetic.go b/test/codegen/arithmetic.go
index b91a904be9..0d6d969000 100644
--- a/test/codegen/arithmetic.go
+++ b/test/codegen/arithmetic.go
@@ -10,6 +10,21 @@ package codegen
 // simplifications and optimizations on integer types.
 // For codegen tests on float types, see floats.go.
 
+// ----------------- //
+//    Addition       //
+// ----------------- //
+
+func AddLargeConst(a uint64, out []uint64) {
+	// ppc64x/power10:"ADD\t[$]4294967296,"
+	// ppc64x/power9:"MOVD\t[$]i64.0000000100000000[(]SB[)]", "ADD\tR[0-9]*"
+	// ppc64x/power8:"MOVD\t[$]i64.0000000100000000[(]SB[)]", "ADD\tR[0-9]*"
+	out[0] = a + 0x100000000
+	// ppc64x/power10:"ADD\t[$]-8589934592,"
+	// ppc64x/power9:"MOVD\t[$]i64.fffffffe00000000[(]SB[)]", "ADD\tR[0-9]*"
+	// ppc64x/power8:"MOVD\t[$]i64.fffffffe00000000[(]SB[)]", "ADD\tR[0-9]*"
+	out[1] = a + 0xFFFFFFFE00000000
+}
+
 // ----------------- //
 //    Subtraction    //
 // ----------------- //