glasm: Initial implementation of phi nodes on GLASM

3 files changed, 81 insertions, 8 deletions

diff --git a/src/shader_recompiler/backend/glasm/emit_glasm.cpp b/src/shader_recompiler/backend/glasm/emit_glasm.cpp
index fa48ba25c..775dd9e7e 100644
--- a/src/shader_recompiler/backend/glasm/emit_glasm.cpp
+++ b/src/shader_recompiler/backend/glasm/emit_glasm.cpp
@@ -2,6 +2,7 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <ranges>
 #include <string>
 #include <tuple>
 
@@ -9,6 +10,7 @@
 #include "shader_recompiler/backend/glasm/emit_context.h"
 #include "shader_recompiler/backend/glasm/emit_glasm.h"
 #include "shader_recompiler/backend/glasm/emit_glasm_instructions.h"
+#include "shader_recompiler/frontend/ir/ir_emitter.h"
 #include "shader_recompiler/frontend/ir/program.h"
 #include "shader_recompiler/profile.h"
 
@@ -175,6 +177,34 @@ void EmitInst(EmitContext& ctx, IR::Inst* inst) {
     throw LogicError("Invalid opcode {}", inst->GetOpcode());
 }
 
+void Precolor(EmitContext& ctx, const IR::Program& program) {
+    for (IR::Block* const block : program.blocks) {
+        for (IR::Inst& phi : block->Instructions() | std::views::take_while(IR::IsPhi)) {
+            switch (phi.Arg(0).Type()) {
+            case IR::Type::U1:
+            case IR::Type::U32:
+            case IR::Type::F32:
+                ctx.reg_alloc.Define(phi);
+                break;
+            case IR::Type::U64:
+            case IR::Type::F64:
+                ctx.reg_alloc.LongDefine(phi);
+                break;
+            default:
+                throw NotImplementedException("Phi node type {}", phi.Type());
+            }
+            const size_t num_args{phi.NumArgs()};
+            for (size_t i = 0; i < num_args; ++i) {
+                IR::IREmitter{*phi.PhiBlock(i)}.PhiMove(phi, phi.Arg(i));
+            }
+            // Add reference to the phi node on the phi predecessor to avoid overwritting it
+            for (size_t i = 0; i < num_args; ++i) {
+                IR::IREmitter{*phi.PhiBlock(i)}.DummyReference(IR::Value{&phi});
+            }
+        }
+    }
+}
+
 void EmitCode(EmitContext& ctx, const IR::Program& program) {
     const auto eval{
         [&](const IR::U1& cond) { return ScalarS32{ctx.reg_alloc.Consume(IR::Value{cond})}; }};
@@ -186,7 +216,9 @@ void EmitCode(EmitContext& ctx, const IR::Program& program) {
             }
             break;
         case IR::AbstractSyntaxNode::Type::If:
-            ctx.Add("MOV.S.CC RC,{};IF NE.x;", eval(node.if_node.cond));
+            ctx.Add("MOV.S.CC RC,{};"
+                    "IF NE.x;",
+                    eval(node.if_node.cond));
             break;
         case IR::AbstractSyntaxNode::Type::EndIf:
             ctx.Add("ENDIF;");
@@ -195,10 +227,30 @@ void EmitCode(EmitContext& ctx, const IR::Program& program) {
             ctx.Add("REP;");
             break;
         case IR::AbstractSyntaxNode::Type::Repeat:
-            ctx.Add("MOV.S.CC RC,{};BRK NE.x;ENDREP;", eval(node.repeat.cond));
+            if (node.repeat.cond.IsImmediate()) {
+                if (node.repeat.cond.U1()) {
+                    ctx.Add("ENDREP;");
+                } else {
+                    ctx.Add("BRK;"
+                            "ENDREP;");
+                }
+            } else {
+                ctx.Add("MOV.S.CC RC,{};"
+                        "BRK (EQ.x);"
+                        "ENDREP;",
+                        eval(node.repeat.cond));
+            }
             break;
         case IR::AbstractSyntaxNode::Type::Break:
-            ctx.Add("MOV.S.CC RC,{};BRK NE.x;", eval(node.repeat.cond));
+            if (node.break_node.cond.IsImmediate()) {
+                if (node.break_node.cond.U1()) {
+                    ctx.Add("BRK;");
+                }
+            } else {
+                ctx.Add("MOV.S.CC RC,{};"
+                        "BRK (NE.x);",
+                        eval(node.break_node.cond));
+            }
             break;
         case IR::AbstractSyntaxNode::Type::Return:
         case IR::AbstractSyntaxNode::Type::Unreachable:
@@ -233,6 +285,7 @@ void SetupOptions(std::string& header, Info info) {
 
 std::string EmitGLASM(const Profile&, IR::Program& program, Bindings&) {
     EmitContext ctx{program};
+    Precolor(ctx, program);
     EmitCode(ctx, program);
     std::string header = "!!NVcp5.0\n"
                          "OPTION NV_internal;";
diff --git a/src/shader_recompiler/backend/glasm/emit_glasm_instructions.h b/src/shader_recompiler/backend/glasm/emit_glasm_instructions.h
index 0f7f16e6e..a74e422d6 100644
--- a/src/shader_recompiler/backend/glasm/emit_glasm_instructions.h
+++ b/src/shader_recompiler/backend/glasm/emit_glasm_instructions.h
@@ -22,7 +22,8 @@ class EmitContext;
 void EmitPhi(EmitContext& ctx, IR::Inst& inst);
 void EmitVoid(EmitContext& ctx);
 void EmitIdentity(EmitContext& ctx, IR::Inst& inst, const IR::Value& value);
-void EmitBranchConditionRef(EmitContext&);
+void EmitDummyReference(EmitContext&);
+void EmitPhiMove(EmitContext& ctx, const IR::Value& phi, const IR::Value& value);
 void EmitJoin(EmitContext& ctx);
 void EmitDemoteToHelperInvocation(EmitContext& ctx);
 void EmitBarrier(EmitContext& ctx);
diff --git a/src/shader_recompiler/backend/glasm/emit_glasm_not_implemented.cpp b/src/shader_recompiler/backend/glasm/emit_glasm_not_implemented.cpp
index f37ad5587..969b91a81 100644
--- a/src/shader_recompiler/backend/glasm/emit_glasm_not_implemented.cpp
+++ b/src/shader_recompiler/backend/glasm/emit_glasm_not_implemented.cpp
@@ -17,13 +17,32 @@ namespace Shader::Backend::GLASM {
 
 #define NotImplemented() throw NotImplementedException("GLASM instruction {}", __LINE__)
 
-void EmitPhi(EmitContext& ctx, IR::Inst& inst) {
-    NotImplemented();
-}
+void EmitPhi(EmitContext&, IR::Inst&) {}
 
 void EmitVoid(EmitContext&) {}
 
-void EmitBranchConditionRef(EmitContext&) {}
+void EmitDummyReference(EmitContext&) {}
+
+void EmitPhiMove(EmitContext& ctx, const IR::Value& phi, const IR::Value& value) {
+    if (phi == value) {
+        return;
+    }
+    const Register phi_reg{ctx.reg_alloc.Consume(phi)};
+    const Value eval_value{ctx.reg_alloc.Consume(value)};
+    switch (phi.InstRecursive()->Arg(0).Type()) {
+    case IR::Type::U1:
+    case IR::Type::U32:
+    case IR::Type::F32:
+        ctx.Add("MOV.S {}.x,{};", phi_reg, ScalarS32{eval_value});
+        break;
+    case IR::Type::U64:
+    case IR::Type::F64:
+        ctx.Add("MOV.U64 {}.x,{};", phi_reg, ScalarRegister{eval_value});
+        break;
+    default:
+        throw NotImplementedException("Phi node type {}", phi.Type());
+    }
+}
 
 void EmitJoin(EmitContext& ctx) {
     NotImplemented();