[llvm] [RISCV] Add short forward branch scheduling for Andes45 (PR #147890)

[Jim Lin via llvm-commits]

https://github.com/tclin914 created https://github.com/llvm/llvm-project/pull/147890

None

>From 5957c167defe5af5e9a3f0104a2f1d72a575e0d5 Mon Sep 17 00:00:00 2001
From: Jim Lin <jim at andestech.com>
Date: Thu, 10 Jul 2025 10:05:37 +0800
Subject: [PATCH] [RISCV] Add short forward branch scheduling for Andes45

---
 llvm/lib/Target/RISCV/RISCVSchedAndes45.td | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/Target/RISCV/RISCVSchedAndes45.td b/llvm/lib/Target/RISCV/RISCVSchedAndes45.td
index bd480aacc539e..214fd8158a679 100644
--- a/llvm/lib/Target/RISCV/RISCVSchedAndes45.td
+++ b/llvm/lib/Target/RISCV/RISCVSchedAndes45.td
@@ -54,6 +54,12 @@ def : WriteRes<WriteShiftImm32, [Andes45ALU]>;
 def : WriteRes<WriteShiftReg, [Andes45ALU]>;
 def : WriteRes<WriteShiftReg32, [Andes45ALU]>;
 
+// Short forward branch
+def : WriteRes<WriteSFB, [Andes45ALU]> {
+  let Latency = 1;
+  let NumMicroOps = 2;
+}
+
 // Branching
 def : WriteRes<WriteJmp, [Andes45ALU]>;
 def : WriteRes<WriteJal, [Andes45ALU]>;
@@ -231,6 +237,8 @@ def : ReadAdvance<ReadShiftImm, 0>;
 def : ReadAdvance<ReadShiftImm32, 0>;
 def : ReadAdvance<ReadShiftReg, 0>;
 def : ReadAdvance<ReadShiftReg32, 0>;
+def : ReadAdvance<ReadSFBJmp, 0>;
+def : ReadAdvance<ReadSFBALU, 0>;
 def : ReadAdvance<ReadJalr, 0>;
 def : ReadAdvance<ReadJmp, 0>;
 def : ReadAdvance<ReadIMul, 0>;
@@ -328,7 +336,6 @@ def : ReadAdvance<ReadCSR, 0>;
 //===----------------------------------------------------------------------===//
 // Unsupported extensions
 defm : UnsupportedSchedQ;
-defm : UnsupportedSchedSFB;
 defm : UnsupportedSchedV;
 defm : UnsupportedSchedXsfvcp;
 defm : UnsupportedSchedXSfvfnrclipxfqf;