Improve style of pg_lfind32().

This commit simplifies pg_lfind32() a bit by moving the standard
one-by-one linear search code to an inline helper function.

Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/20240327013616.GA3940109%40nathanxps13

diff --git a/src/include/port/pg_lfind.h b/src/include/port/pg_lfind.h
index 33e8471b031725e7d29640cd3ca1bfb13fbdeea7..4b1431ed00201777575ef7d41492a75d68b2416b 100644 (file)
--- a/src/include/port/pg_lfind.h
+++ b/src/include/port/pg_lfind.h
@@ -80,6 +80,24 @@ pg_lfind8_le(uint8 key, uint8 *base, uint32 nelem)
    return false;
 }
 
+/*
+ * pg_lfind32_one_by_one_helper
+ *
+ * Searches the array of integers one-by-one.  The caller is responsible for
+ * ensuring that there are at least "nelem" integers in the array.
+ */
+static inline bool
+pg_lfind32_one_by_one_helper(uint32 key, const uint32 *base, uint32 nelem)
+{
+   for (uint32 i = 0; i < nelem; i++)
+   {
+       if (key == base[i])
+           return true;
+   }
+
+   return false;
+}
+
 #ifndef USE_NO_SIMD
 /*
  * pg_lfind32_simd_helper
@@ -88,7 +106,7 @@ pg_lfind8_le(uint8 key, uint8 *base, uint32 nelem)
  * ensuring that there are at least 4-registers-worth of integers remaining.
  */
 static inline bool
-pg_lfind32_simd_helper(const Vector32 keys, uint32 *base)
+pg_lfind32_simd_helper(const Vector32 keys, const uint32 *base)
 {
    const uint32 nelem_per_vector = sizeof(Vector32) / sizeof(uint32);
    Vector32    vals1,
@@ -132,11 +150,10 @@ pg_lfind32_simd_helper(const Vector32 keys, uint32 *base)
  * return false.
  */
 static inline bool
-pg_lfind32(uint32 key, uint32 *base, uint32 nelem)
+pg_lfind32(uint32 key, const uint32 *base, uint32 nelem)
 {
-   uint32      i = 0;
-
 #ifndef USE_NO_SIMD
+   uint32      i = 0;
 
    /*
     * For better instruction-level parallelism, each loop iteration operates
@@ -150,25 +167,15 @@ pg_lfind32(uint32 key, uint32 *base, uint32 nelem)
    const uint32 tail_idx = nelem & ~(nelem_per_iteration - 1);
 
 #if defined(USE_ASSERT_CHECKING)
-   bool        assert_result = false;
-
-   /* pre-compute the result for assert checking */
-   for (int j = 0; j < nelem; j++)
-   {
-       if (key == base[j])
-       {
-           assert_result = true;
-           break;
-       }
-   }
+   bool        assert_result = pg_lfind32_one_by_one_helper(key, base, nelem);
 #endif
 
    /*
-    * If there aren't enough elements for the SIMD code, jump to the standard
+    * If there aren't enough elements for the SIMD code, use the standard
     * one-by-one linear search code.
     */
    if (nelem < nelem_per_iteration)
-       goto one_by_one;
+       return pg_lfind32_one_by_one_helper(key, base, nelem);
 
    /*
     * Process as many elements as possible with a block of 4 registers.
@@ -193,27 +200,10 @@ pg_lfind32(uint32 key, uint32 *base, uint32 nelem)
     */
    Assert(assert_result == pg_lfind32_simd_helper(keys, &base[nelem - nelem_per_iteration]));
    return pg_lfind32_simd_helper(keys, &base[nelem - nelem_per_iteration]);
-
-one_by_one:
-
-#endif                         /* ! USE_NO_SIMD */
-
+#else
    /* Process the elements one at a time. */
-   for (; i < nelem; i++)
-   {
-       if (key == base[i])
-       {
-#ifndef USE_NO_SIMD
-           Assert(assert_result == true);
+   return pg_lfind32_one_by_one_helper(key, base, nelem);
 #endif
-           return true;
-       }
-   }
-
-#ifndef USE_NO_SIMD
-   Assert(assert_result == false);
-#endif
-   return false;
 }
 
 #endif                         /* PG_LFIND_H */