svn commit: r211505 - head/contrib/gcc

[Dimitry Andric]

On 2010-08-20 00:20, Bruce Evans wrote:
> These seem to be needed, and some of them valid.  Any lvalue arg that
> can be put in a register can be cast to USItype (unsigned int) on i386.
> The args are macro args, so they may have any integer type no larger
> than USItype originally, and they must be cast to USItype for the asms
> to work if the args are smaller than USItype...

But will the casts not potentially hide problems, if you pass the wrong
types to those macros?  Maybe it is better if the compiler complains
that some argument is of an incompatible type, than just forcing it to
cast?


>>  which are apparently "heinous" GNU extensions, so clang can
>>  compile this without using the -fheinous-gnu-extensions option.
> 
> But when the args are lvalues, casting them is invalid.  This is
> apparently the heinous extension depended on.

Yes, clang complains precisely about that:

gnu/lib/libgcc/../../../contrib/gcc/libgcc2.c:536:22: error: invalid use of a cast in a inline asm context requiring an l-value: remove the cast or build with -fheinous-gnu-extensions
  DWunion w = {.ll = __umulsidi3 (uu.s.low, vv.s.low)};
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from gnu/lib/libgcc/../../../contrib/gcc/libgcc2.c:65:
In file included from gnu/lib/libgcc/../../../contrib/gcc/libgcc2.h:435:
gnu/lib/libgcc/../../../contrib/gcc/longlong.h:1293:5: note: instantiated from:
    umul_ppmm (__w.s.high, __w.s.low, u, v);                            \
    ^

It turns out that only removing the casts for these specific lvalues is
indeed enough to make clang happy.  Attached patch reverts all other
changes, if that is to be preferred.


>>  Results in *no* binary change, neither with clang, nor with gcc.
> 
> This cannot be tested by compiling a few binaries, since the few binaries
> might not include enough examples to give test coverage of cases with
> args smaller than USItype.  Perhaps the macros are only used for building
> libgcc, but this is unclear.

contrib/gcc/longlong.h is only used in contrib/gcc/libgcc2.h, and in
contrib/gcc/config/soft-fp/soft-fp.h.  On i386, soft-fp is not used,
and libgcc2.h is only used in contrib/gcc/libgcc2.c, so libgcc is the
only consumer, as far as I can see.
-------------- next part --------------
diff --git a/contrib/gcc/longlong.h b/contrib/gcc/longlong.h
index 8805d91..a789d16 100644
--- a/contrib/gcc/longlong.h
+++ b/contrib/gcc/longlong.h
@@ -314,38 +314,38 @@ UDItype __umulsidi3 (USItype, USItype);
 #if (defined (__i386__) || defined (__i486__)) && W_TYPE_SIZE == 32
 #define add_ssaaaa(sh, sl, ah, al, bh, bl) \
   __asm__ ("addl %5,%1\n\tadcl %3,%0"					\
-	   : "=r" (sh),							\
-	     "=&r" (sl)							\
-	   : "%0" (ah),							\
-	     "g" (bh),							\
-	     "%1" (al),							\
-	     "g" (bl))
+	   : "=r" ((USItype) (sh)),					\
+	     "=&r" ((USItype) (sl))					\
+	   : "%0" ((USItype) (ah)),					\
+	     "g" ((USItype) (bh)),					\
+	     "%1" ((USItype) (al)),					\
+	     "g" ((USItype) (bl)))
 #define sub_ddmmss(sh, sl, ah, al, bh, bl) \
   __asm__ ("subl %5,%1\n\tsbbl %3,%0"					\
 	   : "=r" (sh),							\
 	     "=&r" (sl)							\
-	   : "0" (ah),							\
-	     "g" (bh),							\
-	     "1" (al),							\
-	     "g" (bl))
+	   : "0" ((USItype) (ah)),					\
+	     "g" ((USItype) (bh)),					\
+	     "1" ((USItype) (al)),					\
+	     "g" ((USItype) (bl)))
 #define umul_ppmm(w1, w0, u, v) \
   __asm__ ("mull %3"							\
 	   : "=a" (w0),							\
 	     "=d" (w1)							\
-	   : "%0" (u),							\
-	     "rm" (v))
+	   : "%0" ((USItype) (u)),					\
+	     "rm" ((USItype) (v)))
 #define udiv_qrnnd(q, r, n1, n0, dv) \
   __asm__ ("divl %4"							\
 	   : "=a" (q),							\
 	     "=d" (r)							\
-	   : "0" (n0),							\
-	     "1" (n1),							\
-	     "rm" (dv))
+	   : "0" ((USItype) (n0)),					\
+	     "1" ((USItype) (n1)),					\
+	     "rm" ((USItype) (dv)))
 #define count_leading_zeros(count, x) \
   do {									\
     USItype __cbtmp;							\
     __asm__ ("bsrl %1,%0"						\
-	     : "=r" (__cbtmp) : "rm" (x));				\
+	     : "=r" (__cbtmp) : "rm" ((USItype) (x)));			\
     (count) = __cbtmp ^ 31;						\
   } while (0)
 #define count_trailing_zeros(count, x) \