8 files changed, 75 insertions, 18 deletions

diff --git a/src/shader_recompiler/CMakeLists.txt b/src/shader_recompiler/CMakeLists.txt
index 89fc24f62..035fd34e2 100644
--- a/src/shader_recompiler/CMakeLists.txt
+++ b/src/shader_recompiler/CMakeLists.txt
@@ -64,6 +64,7 @@ add_library(shader_recompiler STATIC
     frontend/maxwell/translate/impl/common_encoding.h
     frontend/maxwell/translate/impl/common_funcs.cpp
     frontend/maxwell/translate/impl/common_funcs.h
+    frontend/maxwell/translate/impl/find_leading_one.cpp
     frontend/maxwell/translate/impl/floating_point_add.cpp
     frontend/maxwell/translate/impl/floating_point_conversion_integer.cpp
     frontend/maxwell/translate/impl/floating_point_fused_multiply_add.cpp
diff --git a/src/shader_recompiler/backend/spirv/emit_spirv.h b/src/shader_recompiler/backend/spirv/emit_spirv.h
index 4d00b235d..5446d6ab6 100644
--- a/src/shader_recompiler/backend/spirv/emit_spirv.h
+++ b/src/shader_recompiler/backend/spirv/emit_spirv.h
@@ -229,7 +229,9 @@ Id EmitBitFieldSExtract(EmitContext& ctx, Id base, Id offset, Id count);
 Id EmitBitFieldUExtract(EmitContext& ctx, Id base, Id offset, Id count);
 Id EmitBitReverse32(EmitContext& ctx, Id value);
 Id EmitBitCount32(EmitContext& ctx, Id value);
-Id EmitBitwiseNot32(EmitContext& ctx, Id a);
+Id EmitBitwiseNot32(EmitContext& ctx, Id value);
+Id EmitFindSMsb32(EmitContext& ctx, Id value);
+Id EmitFindUMsb32(EmitContext& ctx, Id value);
 Id EmitSMin32(EmitContext& ctx, Id a, Id b);
 Id EmitUMin32(EmitContext& ctx, Id a, Id b);
 Id EmitSMax32(EmitContext& ctx, Id a, Id b);
diff --git a/src/shader_recompiler/backend/spirv/emit_spirv_integer.cpp b/src/shader_recompiler/backend/spirv/emit_spirv_integer.cpp
index 5bdd943a4..162fb6a91 100644
--- a/src/shader_recompiler/backend/spirv/emit_spirv_integer.cpp
+++ b/src/shader_recompiler/backend/spirv/emit_spirv_integer.cpp
@@ -110,8 +110,16 @@ Id EmitBitCount32(EmitContext& ctx, Id value) {
     return ctx.OpBitCount(ctx.U32[1], value);
 }
 
-Id EmitBitwiseNot32(EmitContext& ctx, Id a) {
-    return ctx.OpNot(ctx.U32[1], a);
+Id EmitBitwiseNot32(EmitContext& ctx, Id value) {
+    return ctx.OpNot(ctx.U32[1], value);
+}
+
+Id EmitFindSMsb32(EmitContext& ctx, Id value) {
+    return ctx.OpFindSMsb(ctx.U32[1], value);
+}
+
+Id EmitFindUMsb32(EmitContext& ctx, Id value) {
+    return ctx.OpFindUMsb(ctx.U32[1], value);
 }
 
 Id EmitSMin32(EmitContext& ctx, Id a, Id b) {
diff --git a/src/shader_recompiler/frontend/ir/ir_emitter.cpp b/src/shader_recompiler/frontend/ir/ir_emitter.cpp
index 04edcdfd8..0f1cab57a 100644
--- a/src/shader_recompiler/frontend/ir/ir_emitter.cpp
+++ b/src/shader_recompiler/frontend/ir/ir_emitter.cpp
@@ -812,8 +812,16 @@ U32 IREmitter::BitCount(const U32& value) {
     return Inst<U32>(Opcode::BitCount32, value);
 }
 
-U32 IREmitter::BitwiseNot(const U32& a) {
-    return Inst<U32>(Opcode::BitwiseNot32, a);
+U32 IREmitter::BitwiseNot(const U32& value) {
+    return Inst<U32>(Opcode::BitwiseNot32, value);
+}
+
+U32 IREmitter::FindSMsb(const U32& value) {
+    return Inst<U32>(Opcode::FindSMsb32, value);
+}
+
+U32 IREmitter::FindUMsb(const U32& value) {
+    return Inst<U32>(Opcode::FindUMsb32, value);
 }
 
 U32 IREmitter::SMin(const U32& a, const U32& b) {
diff --git a/src/shader_recompiler/frontend/ir/ir_emitter.h b/src/shader_recompiler/frontend/ir/ir_emitter.h
index 00ba2e4cd..03a67985f 100644
--- a/src/shader_recompiler/frontend/ir/ir_emitter.h
+++ b/src/shader_recompiler/frontend/ir/ir_emitter.h
@@ -161,8 +161,10 @@ public:
                                       bool is_signed);
     [[nodiscard]] U32 BitReverse(const U32& value);
     [[nodiscard]] U32 BitCount(const U32& value);
-    [[nodiscard]] U32 BitwiseNot(const U32& a);
+    [[nodiscard]] U32 BitwiseNot(const U32& value);
 
+    [[nodiscard]] U32 FindSMsb(const U32& value);
+    [[nodiscard]] U32 FindUMsb(const U32& value);
     [[nodiscard]] U32 SMin(const U32& a, const U32& b);
     [[nodiscard]] U32 UMin(const U32& a, const U32& b);
     [[nodiscard]] U32 SMax(const U32& a, const U32& b);
diff --git a/src/shader_recompiler/frontend/ir/opcodes.inc b/src/shader_recompiler/frontend/ir/opcodes.inc
index 2c4a997dc..aedbc5c3e 100644
--- a/src/shader_recompiler/frontend/ir/opcodes.inc
+++ b/src/shader_recompiler/frontend/ir/opcodes.inc
@@ -235,6 +235,8 @@ OPCODE(BitReverse32,                                        U32,            U32,
 OPCODE(BitCount32,                                          U32,            U32,                                                            )
 OPCODE(BitwiseNot32,                                        U32,            U32,                                                            )
 
+OPCODE(FindSMsb32,                                          U32,            U32,                                                            )
+OPCODE(FindUMsb32,                                          U32,            U32,                                                            )
 OPCODE(SMin32,                                              U32,            U32,            U32,                                            )
 OPCODE(UMin32,                                              U32,            U32,            U32,                                            )
 OPCODE(SMax32,                                              U32,            U32,            U32,                                            )
diff --git a/src/shader_recompiler/frontend/maxwell/translate/impl/find_leading_one.cpp b/src/shader_recompiler/frontend/maxwell/translate/impl/find_leading_one.cpp
new file mode 100644
index 000000000..d5361bec5
--- /dev/null
+++ b/src/shader_recompiler/frontend/maxwell/translate/impl/find_leading_one.cpp
@@ -0,0 +1,46 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "common/bit_field.h"
+#include "common/common_types.h"
+#include "shader_recompiler/frontend/maxwell/translate/impl/impl.h"
+
+namespace Shader::Maxwell {
+namespace {
+void FLO(TranslatorVisitor& v, u64 insn, const IR::U32& src) {
+    union {
+        u64 insn;
+        BitField<0, 8, IR::Reg> dest_reg;
+        BitField<40, 1, u64> tilde;
+        BitField<41, 1, u64> shift;
+        BitField<48, 1, u64> is_signed;
+    } const flo{insn};
+
+    const bool invert{flo.tilde != 0};
+    const bool is_signed{flo.is_signed != 0};
+    const bool shift_op{flo.shift != 0};
+
+    const IR::U32 operand{invert ? v.ir.BitwiseNot(src) : src};
+    const IR::U32 find_result{is_signed ? v.ir.FindSMsb(operand) : v.ir.FindUMsb(operand)};
+    const IR::U1 find_fail{v.ir.IEqual(find_result, v.ir.Imm32(-1))};
+    const IR::U32 offset{v.ir.Imm32(31)};
+    const IR::U32 success_result{shift_op ? IR::U32{v.ir.ISub(offset, find_result)} : find_result};
+
+    const IR::U32 result{v.ir.Select(find_fail, find_result, success_result)};
+    v.X(flo.dest_reg, result);
+}
+} // Anonymous namespace
+
+void TranslatorVisitor::FLO_reg(u64 insn) {
+    FLO(*this, insn, GetReg20(insn));
+}
+
+void TranslatorVisitor::FLO_cbuf(u64 insn) {
+    FLO(*this, insn, GetCbuf(insn));
+}
+
+void TranslatorVisitor::FLO_imm(u64 insn) {
+    FLO(*this, insn, GetImm20(insn));
+}
+} // namespace Shader::Maxwell
diff --git a/src/shader_recompiler/frontend/maxwell/translate/impl/not_implemented.cpp b/src/shader_recompiler/frontend/maxwell/translate/impl/not_implemented.cpp
index f327e6fa5..2da0b87c4 100644
--- a/src/shader_recompiler/frontend/maxwell/translate/impl/not_implemented.cpp
+++ b/src/shader_recompiler/frontend/maxwell/translate/impl/not_implemented.cpp
@@ -217,18 +217,6 @@ void TranslatorVisitor::FCMP_imm(u64) {
     ThrowNotImplemented(Opcode::FCMP_imm);
 }
 
-void TranslatorVisitor::FLO_reg(u64) {
-    ThrowNotImplemented(Opcode::FLO_reg);
-}
-
-void TranslatorVisitor::FLO_cbuf(u64) {
-    ThrowNotImplemented(Opcode::FLO_cbuf);
-}
-
-void TranslatorVisitor::FLO_imm(u64) {
-    ThrowNotImplemented(Opcode::FLO_imm);
-}
-
 void TranslatorVisitor::FMNMX_reg(u64) {
     ThrowNotImplemented(Opcode::FMNMX_reg);
 }