[test] Add tests for 64-bit division

On a 32-bit system, 64-bit division is implemented using the libgcc
functions provided in __udivmoddi4.c etc.  Calls to these functions
are generated automatically by gcc, with a calling convention that is
somewhat empirical in nature.  Add these self-tests primarily as a
check that we are using the correct calling convention.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/tests/math_test.c b/src/tests/math_test.c
index 3967e620119bc5744b9b33cfbdb696c4622886fd..fe61e29c1f01093a6a22209f5bff249da21fb5d3 100644 (file)
--- a/src/tests/math_test.c
+++ b/src/tests/math_test.c
@@ -43,6 +43,54 @@ __attribute__ (( noinline )) int flsl_var ( long value ) {
        return flsl ( value );
 }
 
+/**
+ * Force a use of runtime 64-bit unsigned integer division
+ *
+ * @v dividend         Dividend
+ * @v divisor          Divisor
+ * @ret quotient       Quotient
+ */
+__attribute__ (( noinline )) uint64_t u64div_var ( uint64_t dividend,
+                                                  uint64_t divisor ) {
+       return ( dividend / divisor );
+}
+
+/**
+ * Force a use of runtime 64-bit unsigned integer modulus
+ *
+ * @v dividend         Dividend
+ * @v divisor          Divisor
+ * @ret remainder      Remainder
+ */
+__attribute__ (( noinline )) uint64_t u64mod_var ( uint64_t dividend,
+                                                  uint64_t divisor ) {
+       return ( dividend % divisor );
+}
+
+/**
+ * Force a use of runtime 64-bit signed integer division
+ *
+ * @v dividend         Dividend
+ * @v divisor          Divisor
+ * @ret quotient       Quotient
+ */
+__attribute__ (( noinline )) int64_t s64div_var ( int64_t dividend,
+                                                 int64_t divisor ) {
+       return ( dividend / divisor );
+}
+
+/**
+ * Force a use of runtime 64-bit unsigned integer modulus
+ *
+ * @v dividend         Dividend
+ * @v divisor          Divisor
+ * @ret remainder      Remainder
+ */
+__attribute__ (( noinline )) int64_t s64mod_var ( int64_t dividend,
+                                                 int64_t divisor ) {
+       return ( dividend % divisor );
+}
+
 /**
  * Report a flsl() test result
  *
@@ -62,6 +110,60 @@ flsl_okx ( long value, int msb, const char *file, unsigned int line ) {
 }
 #define flsl_ok( value, msb ) flsl_okx ( value, msb, __FILE__, __LINE__ )
 
+/**
+ * Report a 64-bit unsigned integer division test result
+ *
+ * @v dividend         Dividend
+ * @v divisor          Divisor
+ * @v quotient         Quotient
+ * @v remainder                Remainder
+ * @v file             Test code file
+ * @v line             Test code line
+ */
+static void u64divmod_okx ( uint64_t dividend, uint64_t divisor,
+                           uint64_t quotient, uint64_t remainder,
+                           const char *file, unsigned int line ) {
+
+       /* Sanity check */
+       okx ( ( ( divisor * quotient ) + remainder ) == dividend, file, line );
+
+       /* Check division */
+       okx ( u64div_var ( dividend, divisor ) == quotient, file, line );
+
+       /* Check modulus */
+       okx ( u64mod_var ( dividend, divisor ) == remainder, file, line );
+}
+#define u64divmod_ok( dividend, divisor, quotient, remainder ) \
+       u64divmod_okx ( dividend, divisor, quotient, remainder, \
+                       __FILE__, __LINE__ )
+
+/**
+ * Report a 64-bit signed integer division test result
+ *
+ * @v dividend         Dividend
+ * @v divisor          Divisor
+ * @v quotient         Quotient
+ * @v remainder                Remainder
+ * @v file             Test code file
+ * @v line             Test code line
+ */
+static void s64divmod_okx ( int64_t dividend, int64_t divisor,
+                           int64_t quotient, int64_t remainder,
+                           const char *file, unsigned int line ) {
+
+       /* Sanity check */
+       okx ( ( ( divisor * quotient ) + remainder ) == dividend, file, line );
+
+       /* Check division */
+       okx ( s64div_var ( dividend, divisor ) == quotient, file, line );
+
+       /* Check modulus */
+       okx ( s64mod_var ( dividend, divisor ) == remainder, file, line );
+}
+#define s64divmod_ok( dividend, divisor, quotient, remainder ) \
+       s64divmod_okx ( dividend, divisor, quotient, remainder, \
+                       __FILE__, __LINE__ )
+
 /**
  * Perform mathematical self-tests
  *
@@ -77,6 +179,26 @@ static void math_test_exec ( void ) {
        flsl_ok ( 0x69505845, 31 );
        flsl_ok ( -1U, ( 8 * sizeof ( int ) ) );
        flsl_ok ( -1UL, ( 8 * sizeof ( long ) ) );
+
+       /* Test 64-bit arithmetic
+        *
+        * On a 64-bit machine, these tests are fairly meaningless.
+        *
+        * On a 32-bit machine, these tests verify the correct
+        * operation of our libgcc functions __udivmoddi4()
+        * etc. (including checking that the implicit calling
+        * convention assumed by gcc matches our expectations).
+        */
+       u64divmod_ok ( 0x2b90ddccf699f765ULL, 0xed9f5e73ULL,
+                      0x2eef6ab4ULL, 0x0e12f089ULL );
+       s64divmod_ok ( 0x2b90ddccf699f765ULL, 0xed9f5e73ULL,
+                      0x2eef6ab4ULL, 0x0e12f089ULL );
+       u64divmod_ok ( 0xc09e00dcb9e34b54ULL, 0x35968185cdc744f3ULL,
+                      3, 0x1fda7c4b508d7c7bULL );
+       s64divmod_ok ( -0x3f61ff23461cb4acLL, 0x35968185cdc744f3ULL,
+                      -1LL, -0x9cb7d9d78556fb9LL );
+       u64divmod_ok ( 0, 0x5b2f2737f4ffULL, 0, 0 );
+       s64divmod_ok ( 0, 0xbb00ded72766207fULL, 0, 0 );
 }
 
 /** Mathematical self-tests */