X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=includes%2FStg.h;h=1facd5f40594237d64ee8ca9ed0821afa0320b5e;hp=8e3da0f6d3c3ffba6f660326d82bd75e20907803;hb=65ff44face84ae30f1ddf7d009d51c1778f8c7d3;hpb=983a0f014a12c290ce5efec0b732ad54dd8a281a

diff --git a/includes/Stg.h b/includes/Stg.h
index 8e3da0f..1facd5f 100644
--- a/includes/Stg.h
+++ b/includes/Stg.h
@@ -66,7 +66,9 @@
 #define BITS_IN(x) (BITS_PER_BYTE * sizeof(x))
 
 /*
- * 'Portable' inlining
+ * 'Portable' inlining:
+ * INLINE_HEADER is for inline functions in header files
+ * STATIC_INLINE is for inline functions in source files
  */
 #if defined(__GNUC__) || defined( __INTEL_COMPILER)
 # define INLINE_HEADER static inline
@@ -442,7 +444,9 @@ typedef union {
 
 /* Approximate version when we don't have long arithmetic (on 64-bit archs) */
 
-#define HALF_POS_INT  (((I_)1) << (BITS_IN (I_) / 2))
+/* If we have n-bit words then we have n-1 bits after accounting for the
+ * sign bit, so we can fit the result of multiplying 2 (n-1)/2-bit numbers */
+#define HALF_POS_INT  (((I_)1) << ((BITS_IN (I_) - 1) / 2))
 #define HALF_NEG_INT  (-HALF_POS_INT)
 
 #define mulIntMayOflo(a,b)			\