From 3ee98fd0634dfd864e223353495b862f38555886 Mon Sep 17 00:00:00 2001
From: Brady <zeromemesdev@gmail.com>
Date: Thu, 1 Aug 2024 13:42:19 -0500
Subject: [PATCH] Fetch actual scanner impl

---
 include/libhat/Scanner.hpp | 46 ++++++++++++++++++++++----------------
 src/Scanner.cpp            | 14 +++++-------
 src/arch/x86/AVX2.cpp      | 46 +++++++++++++++++++-------------------
 src/arch/x86/AVX512.cpp    | 46 +++++++++++++++++++-------------------
 src/arch/x86/SSE.cpp       | 46 +++++++++++++++++++-------------------
 5 files changed, 101 insertions(+), 97 deletions(-)

diff --git a/include/libhat/Scanner.hpp b/include/libhat/Scanner.hpp
index 2beb3b3..8f3d883 100644
--- a/include/libhat/Scanner.hpp
+++ b/include/libhat/Scanner.hpp
@@ -105,19 +105,13 @@ namespace hat {
             scan_context() = default;
         };
 
-        template<scan_alignment alignment>
-        [[nodiscard]] std::pair<scan_function_t, size_t> resolve_scanner();
-
-        void apply_hints(scan_context& context);
+        [[nodiscard]] std::pair<scan_function_t, size_t> resolve_scanner(const scan_context&);
 
         enum class scan_mode {
-            FastFirst, // std::find + std::equal
-            SSE,       // x86 SSE 4.1
-            AVX2,      // x86 AVX2
-            AVX512,    // x86 AVX512
-
-            // Fallback mode to use for SIMD remaining bytes
-            Single = FastFirst
+            Single, // std::find + std::equal
+            SSE,    // x86 SSE 4.1
+            AVX2,   // x86 AVX2
+            AVX512, // x86 AVX512
         };
 
         template<scan_alignment alignment>
@@ -132,8 +126,9 @@ namespace hat {
             return mask;
         }
 
-        template<scan_alignment alignment, auto stride = alignment_stride<alignment>>
+        template<scan_alignment alignment>
         inline const std::byte* next_boundary_align(const std::byte* ptr) {
+            constexpr auto stride = alignment_stride<alignment>;
             if constexpr (stride == 1) {
                 return ptr;
             }
@@ -142,8 +137,9 @@ namespace hat {
             return ptr;
         }
 
-        template<scan_alignment alignment, auto stride = alignment_stride<alignment>>
+        template<scan_alignment alignment>
         inline const std::byte* prev_boundary_align(const std::byte* ptr) {
+            constexpr auto stride = alignment_stride<alignment>;
             if constexpr (stride == 1) {
                 return ptr;
             }
@@ -151,11 +147,14 @@ namespace hat {
             return ptr - mod;
         }
 
-        template<scan_mode, scan_alignment>
-        const_scan_result find_pattern(const std::byte* begin, const std::byte* end, const scan_context&);
+        template<scan_mode>
+        scan_function_t get_scanner(const scan_context&);
+
+        template<scan_alignment>
+        const_scan_result find_pattern_single(const std::byte* begin, const std::byte* end, const scan_context&);
 
         template<>
-        inline constexpr const_scan_result find_pattern<scan_mode::FastFirst, scan_alignment::X1>(const std::byte* begin, const std::byte* end, const scan_context& context) {
+        constexpr const_scan_result find_pattern_single<scan_alignment::X1>(const std::byte* begin, const std::byte* end, const scan_context& context) {
             const auto signature = context.signature;
             const auto firstByte = *signature[0];
             const auto scanEnd = end - signature.size() + 1;
@@ -182,7 +181,7 @@ namespace hat {
         }
 
         template<>
-        inline const_scan_result find_pattern<scan_mode::FastFirst, scan_alignment::X16>(const std::byte* begin, const std::byte* end, const scan_context& context) {
+        inline const_scan_result find_pattern_single<scan_alignment::X16>(const std::byte* begin, const std::byte* end, const scan_context& context) {
             const auto signature = context.signature;
             const auto firstByte = *signature[0];
 
@@ -206,6 +205,15 @@ namespace hat {
             return nullptr;
         }
 
+        template<>
+        constexpr scan_function_t get_scanner<scan_mode::Single>(const scan_context& context) {
+            switch (context.alignment) {
+                case scan_alignment::X1: return &find_pattern_single<scan_alignment::X1>;
+                case scan_alignment::X16: return &find_pattern_single<scan_alignment::X16>;
+            }
+            std::unreachable();
+        }
+
         [[nodiscard]] constexpr auto truncate(const signature_view signature) noexcept {
             // Truncate the leading wildcards from the signature
             size_t offset = 0;
@@ -229,9 +237,9 @@ namespace hat {
             ctx.hints = hints;
             ctx.alignment = alignment;
             if LIBHAT_IF_CONSTEVAL {
-                ctx.scanner = &find_pattern<detail::scan_mode::Single, alignment>;
+                ctx.scanner = get_scanner<scan_mode::Single>(ctx);
             } else {
-                std::tie(ctx.scanner, ctx.vectorSize) = resolve_scanner<alignment>();
+                std::tie(ctx.scanner, ctx.vectorSize) = resolve_scanner(ctx);
                 ctx.apply_hints();
             }
             return ctx;
diff --git a/src/Scanner.cpp b/src/Scanner.cpp
index 6d9a7b2..5847fa1 100644
--- a/src/Scanner.cpp
+++ b/src/Scanner.cpp
@@ -7,32 +7,28 @@ namespace hat::detail {
 
     void scan_context::apply_hints() {}
 
-    template<scan_alignment alignment>
-    std::pair<scan_function_t, size_t> resolve_scanner() {
+    std::pair<scan_function_t, size_t> resolve_scanner(const scan_context& context) {
 #if defined(LIBHAT_X86)
         const auto& ext = get_system().extensions;
         if (ext.bmi) {
 #if !defined(LIBHAT_DISABLE_AVX512)
             if (ext.avx512f && ext.avx512bw) {
-                return {&find_pattern<scan_mode::AVX512, alignment>, 64};
+                return {get_scanner<scan_mode::AVX512>(context), 64};
             }
 #endif
             if (ext.avx2) {
-                return {&find_pattern<scan_mode::AVX2, alignment>, 32};
+                return {get_scanner<scan_mode::AVX2>(context), 32};
             }
         }
 #if !defined(LIBHAT_DISABLE_SSE)
         if (ext.sse41) {
-            return {&find_pattern<scan_mode::SSE, alignment>, 16};
+            return {get_scanner<scan_mode::SSE>(context), 16};
         }
 #endif
 #endif
         // If none of the vectorized implementations are available/supported, then fallback to scanning per-byte
-        return {&find_pattern<scan_mode::Single, alignment>, 0};
+        return {get_scanner<scan_mode::Single>(context), 0};
     }
-
-    template std::pair<scan_function_t, size_t> resolve_scanner<scan_alignment::X1>();
-    template std::pair<scan_function_t, size_t> resolve_scanner<scan_alignment::X16>();
 }
 
 // Validate return value const-ness for the root find_pattern impl
diff --git a/src/arch/x86/AVX2.cpp b/src/arch/x86/AVX2.cpp
index 18dc403..17fb134 100644
--- a/src/arch/x86/AVX2.cpp
+++ b/src/arch/x86/AVX2.cpp
@@ -90,34 +90,34 @@ namespace hat::detail {
 
         // Look in remaining bytes that couldn't be grouped into 256 bits
         begin = reinterpret_cast<const std::byte*>(vec);
-        return find_pattern<scan_mode::Single, alignment>(begin, end, context);
+        return find_pattern_single<alignment>(begin, end, context);
     }
 
-    template<scan_alignment alignment>
-    const_scan_result find_pattern_avx2(const std::byte* begin, const std::byte* end, const scan_context& context) {
-        auto& signature = context.signature;
-        const bool cmpeq2 = alignment == scan_alignment::X1 && signature.size() > 1 && signature[1].has_value();
+    template<>
+    scan_function_t get_scanner<scan_mode::AVX2>(const scan_context& context) {
+        const auto alignment = context.alignment;
+        const auto signature = context.signature;
         const bool veccmp = signature.size() <= 33;
 
-        if (cmpeq2 && veccmp) {
-            return find_pattern_avx2<alignment, true, true>(begin, end, context);
-        } else if (cmpeq2) {
-            return find_pattern_avx2<alignment, true, false>(begin, end, context);
-        } else if (veccmp) {
-            return find_pattern_avx2<alignment, false, true>(begin, end, context);
-        } else {
-            return find_pattern_avx2<alignment, false, false>(begin, end, context);
+        if (alignment == scan_alignment::X1) {
+            const bool cmpeq2 = signature.size() > 1 && signature[1].has_value();
+            if (cmpeq2 && veccmp) {
+                return &find_pattern_avx2<scan_alignment::X1, true, true>;
+            } else if (cmpeq2) {
+                return &find_pattern_avx2<scan_alignment::X1, true, false>;
+            } else if (veccmp) {
+                return &find_pattern_avx2<scan_alignment::X1, false, true>;
+            } else {
+                return &find_pattern_avx2<scan_alignment::X1, false, false>;
+            }
+        } else if (alignment == scan_alignment::X16) {
+            if (veccmp) {
+                return &find_pattern_avx2<scan_alignment::X16, false, true>;
+            } else {
+                return &find_pattern_avx2<scan_alignment::X16, false, false>;
+            }
         }
-    }
-
-    template<>
-    const_scan_result find_pattern<scan_mode::AVX2, scan_alignment::X1>(const std::byte* begin, const std::byte* end, const scan_context& context) {
-        return find_pattern_avx2<scan_alignment::X1>(begin, end, context);
-    }
-
-    template<>
-    const_scan_result find_pattern<scan_mode::AVX2, scan_alignment::X16>(const std::byte* begin, const std::byte* end, const scan_context& context) {
-        return find_pattern_avx2<scan_alignment::X16>(begin, end, context);
+        std::unreachable();
     }
 }
 #endif
diff --git a/src/arch/x86/AVX512.cpp b/src/arch/x86/AVX512.cpp
index 1ef28cf..6c7a7f1 100644
--- a/src/arch/x86/AVX512.cpp
+++ b/src/arch/x86/AVX512.cpp
@@ -85,34 +85,34 @@ namespace hat::detail {
 
         // Look in remaining bytes that couldn't be grouped into 512 bits
         begin = reinterpret_cast<const std::byte*>(vec);
-        return find_pattern<scan_mode::Single, alignment>(begin, end, context);
+        return find_pattern_single<alignment>(begin, end, context);
     }
 
-    template<scan_alignment alignment>
-    const_scan_result find_pattern_avx512(const std::byte* begin, const std::byte* end, const scan_context& context) {
-        auto& signature = context.signature;
-        const bool cmpeq2 = alignment == scan_alignment::X1 && signature.size() > 1 && signature[1].has_value();
+    template<>
+    scan_function_t get_scanner<scan_mode::AVX512>(const scan_context& context) {
+        const auto alignment = context.alignment;
+        const auto signature = context.signature;
         const bool veccmp = signature.size() <= 65;
 
-        if (cmpeq2 && veccmp) {
-            return find_pattern_avx512<alignment, true, true>(begin, end, context);
-        } else if (cmpeq2) {
-            return find_pattern_avx512<alignment, true, false>(begin, end, context);
-        } else if (veccmp) {
-            return find_pattern_avx512<alignment, false, true>(begin, end, context);
-        } else {
-            return find_pattern_avx512<alignment, false, false>(begin, end, context);
+        if (alignment == scan_alignment::X1) {
+            const bool cmpeq2 = signature.size() > 1 && signature[1].has_value();
+            if (cmpeq2 && veccmp) {
+                return &find_pattern_avx512<scan_alignment::X1, true, true>;
+            } else if (cmpeq2) {
+                return &find_pattern_avx512<scan_alignment::X1, true, false>;
+            } else if (veccmp) {
+                return &find_pattern_avx512<scan_alignment::X1, false, true>;
+            } else {
+                return &find_pattern_avx512<scan_alignment::X1, false, false>;
+            }
+        } else if (alignment == scan_alignment::X16) {
+            if (veccmp) {
+                return &find_pattern_avx512<scan_alignment::X16, false, true>;
+            } else {
+                return &find_pattern_avx512<scan_alignment::X16, false, false>;
+            }
         }
-    }
-
-    template<>
-    const_scan_result find_pattern<scan_mode::AVX512, scan_alignment::X1>(const std::byte* begin, const std::byte* end, const scan_context& context) {
-        return find_pattern_avx512<scan_alignment::X1>(begin, end, context);
-    }
-
-    template<>
-    const_scan_result find_pattern<scan_mode::AVX512, scan_alignment::X16>(const std::byte* begin, const std::byte* end, const scan_context& context) {
-        return find_pattern_avx512<scan_alignment::X16>(begin, end, context);
+        std::unreachable();
     }
 }
 #endif
diff --git a/src/arch/x86/SSE.cpp b/src/arch/x86/SSE.cpp
index b88c41b..7540707 100644
--- a/src/arch/x86/SSE.cpp
+++ b/src/arch/x86/SSE.cpp
@@ -88,34 +88,34 @@ namespace hat::detail {
 
         // Look in remaining bytes that couldn't be grouped into 128 bits
         begin = reinterpret_cast<const std::byte*>(vec);
-        return find_pattern<scan_mode::Single, alignment>(begin, end, context);
+        return find_pattern_single<alignment>(begin, end, context);
     }
 
-    template<scan_alignment alignment>
-    const_scan_result find_pattern_sse(const std::byte* begin, const std::byte* end, const scan_context& context) {
-        auto& signature = context.signature;
-        const bool cmpeq2 = alignment == scan_alignment::X1 && signature.size() > 1 && signature[1].has_value();
+    template<>
+    scan_function_t get_scanner<scan_mode::SSE>(const scan_context& context) {
+        const auto alignment = context.alignment;
+        const auto signature = context.signature;
         const bool veccmp = signature.size() <= 17;
 
-        if (cmpeq2 && veccmp) {
-            return find_pattern_sse<alignment, true, true>(begin, end, context);
-        } else if (cmpeq2) {
-            return find_pattern_sse<alignment, true, false>(begin, end, context);
-        } else if (veccmp) {
-            return find_pattern_sse<alignment, false, true>(begin, end, context);
-        } else {
-            return find_pattern_sse<alignment, false, false>(begin, end, context);
+        if (alignment == scan_alignment::X1) {
+            const bool cmpeq2 = signature.size() > 1 && signature[1].has_value();
+            if (cmpeq2 && veccmp) {
+                return &find_pattern_sse<scan_alignment::X1, true, true>;
+            } else if (cmpeq2) {
+                return &find_pattern_sse<scan_alignment::X1, true, false>;
+            } else if (veccmp) {
+                return &find_pattern_sse<scan_alignment::X1, false, true>;
+            } else {
+                return &find_pattern_sse<scan_alignment::X1, false, false>;
+            }
+        } else if (alignment == scan_alignment::X16) {
+            if (veccmp) {
+                return &find_pattern_sse<scan_alignment::X16, false, true>;
+            } else {
+                return &find_pattern_sse<scan_alignment::X16, false, false>;
+            }
         }
-    }
-
-    template<>
-    const_scan_result find_pattern<scan_mode::SSE, scan_alignment::X1>(const std::byte* begin, const std::byte* end, const scan_context& context) {
-        return find_pattern_sse<scan_alignment::X1>(begin, end, context);
-    }
-
-    template<>
-    const_scan_result find_pattern<scan_mode::SSE, scan_alignment::X16>(const std::byte* begin, const std::byte* end, const scan_context& context) {
-        return find_pattern_sse<scan_alignment::X16>(begin, end, context);
+        std::unreachable();
     }
 }
 #endif