From 4944213790e4b55ce20f1513b33d2906b1f3700f Mon Sep 17 00:00:00 2001
From: Dylan Reimerink <dylan.reimerink@isovalent.com>
Date: Wed, 1 Nov 2023 08:50:36 +0100
Subject: [PATCH] asm: Add LoadMemSX instruction

ISAv4 adds a new instruction to load a memory value and sign extend it.
To do so a new mode is used. This commit adds a new function to emit
this instruction and adds the logic to print it nicely.

Signed-off-by: Dylan Reimerink <dylan.reimerink@isovalent.com>
---
 asm/instruction.go       |  2 +-
 asm/load_store.go        | 21 +++++++++++++++++++++
 asm/load_store_string.go | 12 ++++++++----
 3 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/asm/instruction.go b/asm/instruction.go
index b8db6cb77..f1b0a186b 100644
--- a/asm/instruction.go
+++ b/asm/instruction.go
@@ -308,7 +308,7 @@ func (ins Instruction) Format(f fmt.State, c rune) {
 			fmt.Fprintf(f, "imm: %d", ins.Constant)
 		case IndMode:
 			fmt.Fprintf(f, "dst: %s src: %s imm: %d", ins.Dst, ins.Src, ins.Constant)
-		case MemMode:
+		case MemMode, MemSXMode:
 			fmt.Fprintf(f, "dst: %s src: %s off: %d imm: %d", ins.Dst, ins.Src, ins.Offset, ins.Constant)
 		case XAddMode:
 			fmt.Fprintf(f, "dst: %s src: %s", ins.Dst, ins.Src)
diff --git a/asm/load_store.go b/asm/load_store.go
index 574ee377c..944db68c1 100644
--- a/asm/load_store.go
+++ b/asm/load_store.go
@@ -24,6 +24,8 @@ const (
 	IndMode Mode = 0x40
 	// MemMode - load from memory
 	MemMode Mode = 0x60
+	// MemSXMode - load from memory, sign extension
+	MemSXMode Mode = 0x80
 	// XAddMode - add atomically across processors.
 	XAddMode Mode = 0xc0
 )
@@ -73,6 +75,11 @@ func LoadMemOp(size Size) OpCode {
 	return OpCode(LdXClass).SetMode(MemMode).SetSize(size)
 }
 
+// LoadSXMemOp returns the OpCode to load a value of given size from memory sign extended.
+func LoadSXMemOp(size Size) OpCode {
+	return OpCode(LdXClass).SetMode(MemSXMode).SetSize(size)
+}
+
 // LoadMem emits `dst = *(size *)(src + offset)`.
 func LoadMem(dst, src Register, offset int16, size Size) Instruction {
 	return Instruction{
@@ -83,6 +90,20 @@ func LoadMem(dst, src Register, offset int16, size Size) Instruction {
 	}
 }
 
+// LoadMemSX emits `dst = *(size *)(src + offset)` but sign extends dst.
+func LoadMemSX(dst, src Register, offset int16, size Size) Instruction {
+	if size == DWord {
+		return Instruction{OpCode: InvalidOpCode}
+	}
+
+	return Instruction{
+		OpCode: LoadSXMemOp(size),
+		Dst:    dst,
+		Src:    src,
+		Offset: offset,
+	}
+}
+
 // LoadImmOp returns the OpCode to load an immediate of given size.
 //
 // As of kernel 4.20, only DWord size is accepted.
diff --git a/asm/load_store_string.go b/asm/load_store_string.go
index 76d29a075..c48080327 100644
--- a/asm/load_store_string.go
+++ b/asm/load_store_string.go
@@ -13,6 +13,7 @@ func _() {
 	_ = x[AbsMode-32]
 	_ = x[IndMode-64]
 	_ = x[MemMode-96]
+	_ = x[MemSXMode-128]
 	_ = x[XAddMode-192]
 }
 
@@ -21,8 +22,9 @@ const (
 	_Mode_name_1 = "AbsMode"
 	_Mode_name_2 = "IndMode"
 	_Mode_name_3 = "MemMode"
-	_Mode_name_4 = "XAddMode"
-	_Mode_name_5 = "InvalidMode"
+	_Mode_name_4 = "MemSXMode"
+	_Mode_name_5 = "XAddMode"
+	_Mode_name_6 = "InvalidMode"
 )
 
 func (i Mode) String() string {
@@ -35,10 +37,12 @@ func (i Mode) String() string {
 		return _Mode_name_2
 	case i == 96:
 		return _Mode_name_3
-	case i == 192:
+	case i == 128:
 		return _Mode_name_4
-	case i == 255:
+	case i == 192:
 		return _Mode_name_5
+	case i == 255:
+		return _Mode_name_6
 	default:
 		return "Mode(" + strconv.FormatInt(int64(i), 10) + ")"
 	}