Optionally support 32-bit builds

This can be useful when building for WASM targets, as well as for legacy systems that run on 32-bit. The relevant code is enabled at compile time by checking the pointer size (__SIZEOF_POINTER__ == 4).
pganalyze · Dec 29, 2023 · 7262c13 · 7262c13
1 parent 2a00188
commit 7262c13
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Showing 4 changed files with 70 additions and 1 deletion.
diff --git a/Makefile b/Makefile
@@ -153,6 +153,28 @@ $(PGDIR):
 	echo "#if defined(__FreeBSD__) || defined(__NetBSD__) || (defined(__GLIBC__) && ((__GLIBC__ == 2 && __GLIBC_MINOR__ >= 38) || __GLIBC__ > 2))" >> $(PGDIR)/src/include/pg_config.h
 	echo "#define HAVE_STRCHRNUL" >> $(PGDIR)/src/include/pg_config.h
 	echo "#endif" >> $(PGDIR)/src/include/pg_config.h
+	# Optionally support 32-bit
+	echo "#if defined(_WIN32) || __SIZEOF_POINTER__ == 4" >> $(PGDIR)/src/include/pg_config.h
+	echo "#undef ALIGNOF_DOUBLE" >> $(PGDIR)/src/include/pg_config.h
+	echo "#define ALIGNOF_DOUBLE 4" >> $(PGDIR)/src/include/pg_config.h
+	echo "#undef ALIGNOF_LONG" >> $(PGDIR)/src/include/pg_config.h
+	echo "#define ALIGNOF_LONG 4" >> $(PGDIR)/src/include/pg_config.h
+	echo "#define ALIGNOF_LONG_LONG_INT 4" >> $(PGDIR)/src/include/pg_config.h
+	echo "#undef ALIGNOF_PG_INT128_TYPE" >> $(PGDIR)/src/include/pg_config.h
+	echo "#undef HAVE_LONG_INT_64" >> $(PGDIR)/src/include/pg_config.h
+	echo "#define HAVE_LONG_LONG_INT_64 1" >> $(PGDIR)/src/include/pg_config.h
+	echo "#undef INT64_MODIFIER" >> $(PGDIR)/src/include/pg_config.h
+	echo "#define INT64_MODIFIER \"ll\"" >> $(PGDIR)/src/include/pg_config.h
+	echo "#undef PG_INT128_TYPE" >> $(PGDIR)/src/include/pg_config.h
+	echo "#undef PG_INT64_TYPE" >> $(PGDIR)/src/include/pg_config.h
+	echo "#define PG_INT64_TYPE long long int" >> $(PGDIR)/src/include/pg_config.h
+	echo "#undef SIZEOF_LONG" >> $(PGDIR)/src/include/pg_config.h
+	echo "#define SIZEOF_LONG 4" >> $(PGDIR)/src/include/pg_config.h
+	echo "#undef SIZEOF_SIZE_T" >> $(PGDIR)/src/include/pg_config.h
+	echo "#define SIZEOF_SIZE_T 4" >> $(PGDIR)/src/include/pg_config.h
+	echo "#undef SIZEOF_VOID_P" >> $(PGDIR)/src/include/pg_config.h
+	echo "#define SIZEOF_VOID_P 4" >> $(PGDIR)/src/include/pg_config.h
+	echo "#endif" >> $(PGDIR)/src/include/pg_config.h
 
 extract_source: $(PGDIR)
 	-@ $(RM) -rf ./src/postgres/

diff --git a/scripts/extract_source.rb b/scripts/extract_source.rb
@@ -586,6 +586,12 @@ def write_out
 # Other required functions
 runner.deep_resolve('pg_printf')
 
+# Retain these functions for optional 32-bit support
+# (see BITS_PER_BITMAPWORD checks in bitmapset.c)
+runner.deep_resolve('pg_leftmost_one_pos32')
+runner.deep_resolve('pg_rightmost_one_pos32')
+runner.deep_resolve('pg_popcount32')
+
 runner.write_out
 
 #puts runner.unresolved.inspect

diff --git a/src/postgres/include/pg_config.h b/src/postgres/include/pg_config.h
@@ -841,3 +841,24 @@
 #if defined(__FreeBSD__) || defined(__NetBSD__) || (defined(__GLIBC__) && ((__GLIBC__ == 2 && __GLIBC_MINOR__ >= 38) || __GLIBC__ > 2))
 #define HAVE_STRCHRNUL
 #endif
+#if defined(_WIN32) || __SIZEOF_POINTER__ == 4
+#undef ALIGNOF_DOUBLE
+#define ALIGNOF_DOUBLE 4
+#undef ALIGNOF_LONG
+#define ALIGNOF_LONG 4
+#define ALIGNOF_LONG_LONG_INT 4
+#undef ALIGNOF_PG_INT128_TYPE
+#undef HAVE_LONG_INT_64
+#define HAVE_LONG_LONG_INT_64 1
+#undef INT64_MODIFIER
+#define INT64_MODIFIER "ll"
+#undef PG_INT128_TYPE
+#undef PG_INT64_TYPE
+#define PG_INT64_TYPE long long int
+#undef SIZEOF_LONG
+#define SIZEOF_LONG 4
+#undef SIZEOF_SIZE_T
+#define SIZEOF_SIZE_T 4
+#undef SIZEOF_VOID_P
+#define SIZEOF_VOID_P 4
+#endif
diff --git a/src/postgres/src_port_pg_bitutils.c b/src/postgres/src_port_pg_bitutils.c
@@ -2,6 +2,8 @@
  * Symbols referenced in this file:
  * - pg_popcount64
  * - pg_popcount64_slow
+ * - pg_popcount32
+ * - pg_popcount32_slow
  *--------------------------------------------------------------------
  */
 
@@ -175,9 +177,23 @@ __asm__ __volatile__(" popcntq %1,%0\n":"=q"(res):"rm"(word):"cc");
  * pg_popcount32_slow
  *		Return the number of 1 bits set in word
  */
+static int
+pg_popcount32_slow(uint32 word)
+{
 #ifdef HAVE__BUILTIN_POPCOUNT
+	return __builtin_popcount(word);
 #else							/* !HAVE__BUILTIN_POPCOUNT */
+	int			result = 0;
+
+	while (word != 0)
+	{
+		result += pg_number_of_ones[word & 255];
+		word >>= 8;
+	}
+
+	return result;
 #endif							/* HAVE__BUILTIN_POPCOUNT */
+}
 
 /*
  * pg_popcount64_slow
@@ -216,7 +232,11 @@ pg_popcount64_slow(uint64 word)
  * TRY_POPCNT_FAST is not defined.  The compiler should be able to inline
  * the slow versions here.
  */
-
+int
+pg_popcount32(uint32 word)
+{
+	return pg_popcount32_slow(word);
+}
 
 int
 pg_popcount64(uint64 word)