From 4b8a8b2a288ddbf3f6aeeb911b95cf548db93cef Mon Sep 17 00:00:00 2001
From: Benjamin Lee <benjamin@computer.surgery>
Date: Sat, 11 Nov 2023 15:58:02 -0800
Subject: [PATCH] nak: use carry register file for IADD2

This allows detecting dependencies between IADD.X and IADD.CC, which is
necessary for SM50 sched and DCE.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26114>
---
 src/nouveau/compiler/nak/builder.rs     | 13 +++++++------
 src/nouveau/compiler/nak/encode_sm50.rs | 19 +++++++++++++++----
 src/nouveau/compiler/nak/ir.rs          | 21 ++++++++-------------
 3 files changed, 30 insertions(+), 23 deletions(-)

diff --git a/src/nouveau/compiler/nak/builder.rs b/src/nouveau/compiler/nak/builder.rs
index 8e116d2c741..0f377799246 100644
--- a/src/nouveau/compiler/nak/builder.rs
+++ b/src/nouveau/compiler/nak/builder.rs
@@ -196,8 +196,8 @@ pub trait SSABuilder: Builder {
             self.push_op(OpIAdd2 {
                 dst: dst.into(),
                 srcs: [x, y],
-                carry_in: false,
-                carry_out: false,
+                carry_in: 0.into(),
+                carry_out: Dst::None,
             });
         }
         dst
@@ -221,17 +221,18 @@ pub trait SSABuilder: Builder {
                 carry: [carry.into(), false.into()],
             });
         } else {
+            let carry = self.alloc_ssa(RegFile::Carry, 1);
             self.push_op(OpIAdd2 {
                 dst: dst[0].into(),
                 srcs: [x[0].into(), y[0].into()],
-                carry_out: true,
-                carry_in: false,
+                carry_out: carry.into(),
+                carry_in: 0.into(),
             });
             self.push_op(OpIAdd2 {
                 dst: dst[1].into(),
                 srcs: [x[1].into(), y[1].into()],
-                carry_out: false,
-                carry_in: true,
+                carry_out: Dst::None,
+                carry_in: carry.into(),
             });
         }
         dst
diff --git a/src/nouveau/compiler/nak/encode_sm50.rs b/src/nouveau/compiler/nak/encode_sm50.rs
index fb54e0159d3..5ab25ae6cbd 100644
--- a/src/nouveau/compiler/nak/encode_sm50.rs
+++ b/src/nouveau/compiler/nak/encode_sm50.rs
@@ -1885,6 +1885,17 @@ impl SM50Instr {
     }
 
     fn encode_iadd2(&mut self, op: &OpIAdd2) {
+        let carry_in = match op.carry_in.src_ref {
+            SrcRef::Reg(reg) if reg.file() == RegFile::Carry => true,
+            SrcRef::Zero => false,
+            other => panic!("invalid carry_in src for IADD2 {other}"),
+        };
+        let carry_out = match op.carry_out {
+            Dst::Reg(reg) if reg.file() == RegFile::Carry => true,
+            Dst::None => false,
+            other => panic!("invalid carry_out dst for IADD2 {other}"),
+        };
+
         if let Some(imm32) = op.srcs[1].as_imm_not_i20() {
             self.set_opcode(0x1c00);
 
@@ -1892,8 +1903,8 @@ impl SM50Instr {
             self.set_reg_ineg_src(8..16, 56, op.srcs[0]);
             self.set_src_imm32(20..56, imm32);
 
-            self.set_bit(53, op.carry_in);
-            self.set_bit(52, op.carry_out);
+            self.set_bit(53, carry_in);
+            self.set_bit(52, carry_out);
         } else {
             match &op.srcs[1].src_ref {
                 SrcRef::Zero | SrcRef::Reg(_) => {
@@ -1914,8 +1925,8 @@ impl SM50Instr {
             self.set_dst(op.dst);
             self.set_reg_ineg_src(8..16, 49, op.srcs[0]);
 
-            self.set_bit(43, op.carry_in);
-            self.set_bit(47, op.carry_out);
+            self.set_bit(43, carry_in);
+            self.set_bit(47, carry_out);
         }
     }
 
diff --git a/src/nouveau/compiler/nak/ir.rs b/src/nouveau/compiler/nak/ir.rs
index b38f1d9938f..0077029d692 100644
--- a/src/nouveau/compiler/nak/ir.rs
+++ b/src/nouveau/compiler/nak/ir.rs
@@ -2491,25 +2491,20 @@ impl_display_for_op!(OpINeg);
 #[derive(SrcsAsSlice, DstsAsSlice)]
 pub struct OpIAdd2 {
     pub dst: Dst,
+    pub carry_out: Dst,
 
     #[src_type(ALU)]
     pub srcs: [Src; 2],
-
-    // TODO: We should probably track this as an SSA value somehow
-    pub carry_out: bool,
-    pub carry_in: bool,
+    pub carry_in: Src,
 }
 
 impl DisplayOp for OpIAdd2 {
     fn fmt_op(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "iadd")?;
-        if self.carry_in {
-            write!(f, ".x")?;
+        write!(f, "iadd2 {} {}", self.srcs[0], self.srcs[1])?;
+        if !self.carry_in.is_zero() {
+            write!(f, " {}", self.carry_in)?;
         }
-        if self.carry_out {
-            write!(f, ".cc")?;
-        }
-        write!(f, " {} {}", self.srcs[0], self.srcs[1])
+        Ok(())
     }
 }
 
@@ -5498,8 +5493,8 @@ impl Shader {
                         instr.op = Op::IAdd2(OpIAdd2 {
                             dst: neg.dst,
                             srcs: [0.into(), neg.src.ineg()],
-                            carry_in: false,
-                            carry_out: false,
+                            carry_in: 0.into(),
+                            carry_out: Dst::None,
                         });
                     }
                     MappedInstrs::One(instr)