From 37edba4da759e8a969bfcd86ca88908ab2c60b38 Mon Sep 17 00:00:00 2001
From: Paul Mackerras <paulus@ozlabs.org>
Date: Thu, 11 Dec 2025 09:01:41 +1100
Subject: [PATCH] FPU: Normalize B operand for multiply-add instructions

Otherwise the result can get rounded incorrectly when B is denorm but
the A * C product is much smaller.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
---
 fpu.vhdl | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fpu.vhdl b/fpu.vhdl
index 014f9ee..53027ff 100644
--- a/fpu.vhdl
+++ b/fpu.vhdl
@@ -1149,6 +1149,7 @@ begin
                             v.is_subtract := not (e_in.fra(63) xor e_in.frb(63) xor
                                                   e_in.frc(63) xor e_in.insn(1));
                             v.negate := e_in.insn(2);
+                            v.do_renorm_b := '1';
                         when "10010" =>         -- fdiv
                             v.is_inverse := '1';
                             v.result_sign := e_in.fra(63) xor e_in.frb(63);