Loongarch Support

src/snmalloc/aal/aal.h

@@ -41,6 +41,10 @@
 #  define PLATFORM_IS_RISCV
 #endif
 
+#if defined(__loongarch__)
+#  define PLATFORM_IS_LOONGARCH
+#endif
+
 namespace snmalloc
 {
   /**
@@ -230,6 +234,8 @@ namespace snmalloc
 #  include "aal_sparc.h"
 #elif defined(PLATFORM_IS_RISCV)
 #  include "aal_riscv.h"
+#elif defined(PLATFORM_IS_LOONGARCH)
+#  include "aal_loongarch.h"
 #endif
 
 #if defined(__CHERI_PURE_CAPABILITY__)

src/snmalloc/aal/aal_consts.h

@@ -33,6 +33,7 @@ namespace snmalloc
     X86,
     X86_SGX,
     Sparc,
-    RISCV
+    RISCV,
+    LoongArch
   };
 } // namespace snmalloc

src/snmalloc/aal/aal_loongarch.h

@@ -0,0 +1,57 @@
+#pragma once
+
+#if __SIZEOF_POINTER__ == 8
+#  define SNMALLOC_VA_BITS_64
+#else
+#  define SNMALLOC_VA_BITS_32
+#endif
+
+#include <cstddef>
+namespace snmalloc
+{
+  /**
+   * Loongarch-specific architecture abstraction layer.
+   */
+  class AAL_LoongArch
+  {
+  public:
+    /**
+     * Bitmap of AalFeature flags
+     */
+    static constexpr uint64_t aal_features =
+      IntegerPointers | NoCpuCycleCounters;
+
+    static constexpr enum AalName aal_name = LoongArch;
+
+    static constexpr size_t smallest_page_size = 0x1000;
+
+    /**
+     * On pipelined processors, notify the core that we are in a spin loop and
+     * that speculative execution past this point may not be a performance gain.
+     */
+    static inline void pause()
+    {
+      __asm__ __volatile__("dbar 0" : : : "memory");
+    }
+
+    /**
+     * PRELD reads a cache-line of data from memory in advance into the Cache.
+     * The access address is the 12bit immediate number of the value in the
+     * general register rj plus the symbol extension.
+     *
+     * The processor learns from the hint in the PRELD instruction what type
+     * will be acquired and which level of Cache the data to be taken back fill
+     * in, hint has 32 optional values (0 to 31), 0 represents load to level 1
+     * Cache If the Cache attribute of the access address of the PRELD
+     * instruction is not cached, then the instruction cannot generate a memory
+     * access action and is treated as a NOP instruction. The PRELD instruction
+     * will not trigger any exceptions related to MMU or address.
+     */
+    static inline void prefetch(void* ptr)
+    {
+      __asm__ volatile("preld 0, %0, 0" : "=r"(ptr));
+    }
+  };
+
+  using AAL_Arch = AAL_LoongArch;
+} // namespace snmalloc

src/snmalloc/pal/pal_linux.h

@@ -29,8 +29,9 @@ namespace snmalloc
      */
     static constexpr uint64_t pal_features = PALPOSIX::pal_features | Entropy;
 
-    static constexpr size_t page_size =
-      Aal::aal_name == PowerPC ? 0x10000 : PALPOSIX::page_size;
+    static constexpr size_t page_size = Aal::aal_name == PowerPC ?
+      0x10000 :
+      (Aal::aal_name == LoongArch ? 0x4000 : PALPOSIX::page_size);
 
     /**
      * Linux requires an explicit no-reserve flag in `mmap` to guarantee lazy