[llvm-commits] [compiler-rt] r158996 - in /compiler-rt/trunk/lib: divsi3.c udivsi3.c

[Stephen Canon]

Author: scanon
Date: Fri Jun 22 09:44:13 2012
New Revision: 158996

URL: http://llvm.org/viewvc/llvm-project?rev=158996&view=rev
Log:
Allow divsi3 to take advantage of a hardware unsigned divide when it is available, by replacing an explicit call to udivsi3 with the divide operator.  Patch by Sébastien Bourdeauducq.

Modified:
    compiler-rt/trunk/lib/divsi3.c
    compiler-rt/trunk/lib/udivsi3.c

Modified: compiler-rt/trunk/lib/divsi3.c
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/divsi3.c?rev=158996&r1=158995&r2=158996&view=diff
==============================================================================
--- compiler-rt/trunk/lib/divsi3.c (original)
+++ compiler-rt/trunk/lib/divsi3.c Fri Jun 22 09:44:13 2012
@@ -29,5 +29,11 @@
     a = (a ^ s_a) - s_a;                         /* negate if s_a == -1 */
     b = (b ^ s_b) - s_b;                         /* negate if s_b == -1 */
     s_a ^= s_b;                                  /* sign of quotient */
-    return (__udivsi3(a, b) ^ s_a) - s_a;        /* negate if s_a == -1 */
+    /*
+     * On CPUs without unsigned hardware division support,
+     *  this calls __udivsi3 (notice the cast to su_int).
+     * On CPUs with unsigned hardware division support,
+     *  this uses the unsigned division instruction.
+     */
+    return ((su_int)a/(su_int)b ^ s_a) - s_a;    /* negate if s_a == -1 */
 }

Modified: compiler-rt/trunk/lib/udivsi3.c
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/udivsi3.c?rev=158996&r1=158995&r2=158996&view=diff
==============================================================================
--- compiler-rt/trunk/lib/udivsi3.c (original)
+++ compiler-rt/trunk/lib/udivsi3.c Fri Jun 22 09:44:13 2012
@@ -20,6 +20,7 @@
 
 ARM_EABI_FNALIAS(uidiv, udivsi3);
 
+/* This function should not call __divsi3! */
 COMPILER_RT_ABI su_int
 __udivsi3(su_int n, su_int d)
 {