[PATCH v2] powerpc/math-emu: Update macros from gmp-6.1.2

Joel Stanley joel at jms.id.au
Wed Nov 14 13:44:12 AEDT 2018


The add_ssaaaa, sub_ddmmss, umul_ppmm and udiv_qrnnd macros originate
from GMP's longlong.h.
This was found when compiling with clang:

   arch/powerpc/math-emu/fnmsub.c:46:2: error: invalid use of a cast in a
   inline asm context requiring an l-value: remove the cast or build with
   -fheinous-gnu-extensions
           FP_ADD_D(R, T, B);
           ^~~~~~~~~~~~~~~~~
   ...

   ./arch/powerpc/include/asm/sfp-machine.h:283:27: note: expanded from
   macro 'sub_ddmmss'
                  : "=r" ((USItype)(sh)),                                  \
                          ~~~~~~~~~~^~~

Segher points out: this was fixed in GCC over 16 years ago
( https://gcc.gnu.org/r56600 ), and in GMP (where it comes from)
presumably before that.

Update to the latest version in order to git rid of the invalid casts.

The only functional change I noticed was this in udiv_qrnnd.

    __r1 = (n1) % __d1;
    __q1 = (n1) / __d1;

Becomes this:

    __q1 = (n1) / __d1;
    __r1 = (n1) - __q1 * __d1;

This is equivalent as it instead of calculating the remainder
using modulo, it uses the result of integer division to subtract the
count of 'whole' d1 from r1.

Link: https://github.com/ClangBuiltLinux/linux/issues/260
Signed-off-by: Joel Stanley <joel at jms.id.au>
---
v1:
 https://lore.kernel.org/linuxppc-dev/20181102033713.31916-1-joel@jms.id.au/
v2:
 Instead of setting the -fheinous-gnu-extensions for clang, fix the code.

 arch/powerpc/include/asm/sfp-machine.h | 99 +++++++++-----------------
 1 file changed, 32 insertions(+), 67 deletions(-)

diff --git a/arch/powerpc/include/asm/sfp-machine.h b/arch/powerpc/include/asm/sfp-machine.h
index d89beaba26ff..a6353d9dd5ba 100644
--- a/arch/powerpc/include/asm/sfp-machine.h
+++ b/arch/powerpc/include/asm/sfp-machine.h
@@ -213,30 +213,18 @@
  * respectively.  The result is placed in HIGH_SUM and LOW_SUM.  Overflow
  * (i.e. carry out) is not stored anywhere, and is lost.
  */
-#define add_ssaaaa(sh, sl, ah, al, bh, bl)				\
+#define add_ssaaaa(sh, sl, ah, al, bh, bl) \
   do {									\
     if (__builtin_constant_p (bh) && (bh) == 0)				\
-      __asm__ ("{a%I4|add%I4c} %1,%3,%4\n\t{aze|addze} %0,%2"		\
-	     : "=r" ((USItype)(sh)),					\
-	       "=&r" ((USItype)(sl))					\
-	     : "%r" ((USItype)(ah)),					\
-	       "%r" ((USItype)(al)),					\
-	       "rI" ((USItype)(bl)));					\
-    else if (__builtin_constant_p (bh) && (bh) ==~(USItype) 0)		\
-      __asm__ ("{a%I4|add%I4c} %1,%3,%4\n\t{ame|addme} %0,%2"		\
-	     : "=r" ((USItype)(sh)),					\
-	       "=&r" ((USItype)(sl))					\
-	     : "%r" ((USItype)(ah)),					\
-	       "%r" ((USItype)(al)),					\
-	       "rI" ((USItype)(bl)));					\
+      __asm__ ("add%I4c %1,%3,%4\n\taddze %0,%2"			\
+	     : "=r" (sh), "=&r" (sl) : "r" (ah), "%r" (al), "rI" (bl));	\
+    else if (__builtin_constant_p (bh) && (bh) == ~(USItype) 0)		\
+      __asm__ ("add%I4c %1,%3,%4\n\taddme %0,%2"			\
+	     : "=r" (sh), "=&r" (sl) : "r" (ah), "%r" (al), "rI" (bl));	\
     else								\
-      __asm__ ("{a%I5|add%I5c} %1,%4,%5\n\t{ae|adde} %0,%2,%3"		\
-	     : "=r" ((USItype)(sh)),					\
-	       "=&r" ((USItype)(sl))					\
-	     : "%r" ((USItype)(ah)),					\
-	       "r" ((USItype)(bh)),					\
-	       "%r" ((USItype)(al)),					\
-	       "rI" ((USItype)(bl)));					\
+      __asm__ ("add%I5c %1,%4,%5\n\tadde %0,%2,%3"			\
+	     : "=r" (sh), "=&r" (sl)					\
+	     : "r" (ah), "r" (bh), "%r" (al), "rI" (bl));		\
   } while (0)
 
 /* sub_ddmmss is used in op-2.h and udivmodti4.c and should be equivalent to
@@ -248,44 +236,24 @@
  * and LOW_DIFFERENCE.  Overflow (i.e. carry out) is not stored anywhere,
  * and is lost.
  */
-#define sub_ddmmss(sh, sl, ah, al, bh, bl)				\
+#define sub_ddmmss(sh, sl, ah, al, bh, bl) \
   do {									\
     if (__builtin_constant_p (ah) && (ah) == 0)				\
-      __asm__ ("{sf%I3|subf%I3c} %1,%4,%3\n\t{sfze|subfze} %0,%2"	\
-	       : "=r" ((USItype)(sh)),					\
-		 "=&r" ((USItype)(sl))					\
-	       : "r" ((USItype)(bh)),					\
-		 "rI" ((USItype)(al)),					\
-		 "r" ((USItype)(bl)));					\
-    else if (__builtin_constant_p (ah) && (ah) ==~(USItype) 0)		\
-      __asm__ ("{sf%I3|subf%I3c} %1,%4,%3\n\t{sfme|subfme} %0,%2"	\
-	       : "=r" ((USItype)(sh)),					\
-		 "=&r" ((USItype)(sl))					\
-	       : "r" ((USItype)(bh)),					\
-		 "rI" ((USItype)(al)),					\
-		 "r" ((USItype)(bl)));					\
+      __asm__ ("subf%I3c %1,%4,%3\n\tsubfze %0,%2"			\
+	       : "=r" (sh), "=&r" (sl) : "r" (bh), "rI" (al), "r" (bl));\
+    else if (__builtin_constant_p (ah) && (ah) == ~(USItype) 0)		\
+      __asm__ ("subf%I3c %1,%4,%3\n\tsubfme %0,%2"			\
+	       : "=r" (sh), "=&r" (sl) : "r" (bh), "rI" (al), "r" (bl));\
     else if (__builtin_constant_p (bh) && (bh) == 0)			\
-      __asm__ ("{sf%I3|subf%I3c} %1,%4,%3\n\t{ame|addme} %0,%2"		\
-	       : "=r" ((USItype)(sh)),					\
-		 "=&r" ((USItype)(sl))					\
-	       : "r" ((USItype)(ah)),					\
-		 "rI" ((USItype)(al)),					\
-		 "r" ((USItype)(bl)));					\
-    else if (__builtin_constant_p (bh) && (bh) ==~(USItype) 0)		\
-      __asm__ ("{sf%I3|subf%I3c} %1,%4,%3\n\t{aze|addze} %0,%2"		\
-	       : "=r" ((USItype)(sh)),					\
-		 "=&r" ((USItype)(sl))					\
-	       : "r" ((USItype)(ah)),					\
-		 "rI" ((USItype)(al)),					\
-		 "r" ((USItype)(bl)));					\
+      __asm__ ("subf%I3c %1,%4,%3\n\taddme %0,%2"			\
+	       : "=r" (sh), "=&r" (sl) : "r" (ah), "rI" (al), "r" (bl));\
+    else if (__builtin_constant_p (bh) && (bh) == ~(USItype) 0)		\
+      __asm__ ("subf%I3c %1,%4,%3\n\taddze %0,%2"			\
+	       : "=r" (sh), "=&r" (sl) : "r" (ah), "rI" (al), "r" (bl));\
     else								\
-      __asm__ ("{sf%I4|subf%I4c} %1,%5,%4\n\t{sfe|subfe} %0,%3,%2"	\
-	       : "=r" ((USItype)(sh)),					\
-		 "=&r" ((USItype)(sl))					\
-	       : "r" ((USItype)(ah)),					\
-		 "r" ((USItype)(bh)),					\
-		 "rI" ((USItype)(al)),					\
-		 "r" ((USItype)(bl)));					\
+      __asm__ ("subf%I4c %1,%5,%4\n\tsubfe %0,%3,%2"			\
+	       : "=r" (sh), "=&r" (sl)					\
+	       : "r" (ah), "r" (bh), "rI" (al), "r" (bl));		\
   } while (0)
 
 /* asm fragments for mul and div */
@@ -294,13 +262,10 @@
  * UWtype integers MULTIPLER and MULTIPLICAND, and generates a two UWtype
  * word product in HIGH_PROD and LOW_PROD.
  */
-#define umul_ppmm(ph, pl, m0, m1)					\
+#define umul_ppmm(ph, pl, m0, m1) \
   do {									\
     USItype __m0 = (m0), __m1 = (m1);					\
-    __asm__ ("mulhwu %0,%1,%2"						\
-	     : "=r" ((USItype)(ph))					\
-	     : "%r" (__m0),						\
-               "r" (__m1));						\
+    __asm__ ("mulhwu %0,%1,%2" : "=r" (ph) : "%r" (m0), "r" (m1));	\
     (pl) = __m0 * __m1;							\
   } while (0)
 
@@ -312,28 +277,28 @@
  * significant bit of DENOMINATOR must be 1, then the pre-processor symbol
  * UDIV_NEEDS_NORMALIZATION is defined to 1.
  */
-#define udiv_qrnnd(q, r, n1, n0, d)					\
+#define udiv_qrnnd(q, r, n1, n0, d) \
   do {									\
     UWtype __d1, __d0, __q1, __q0, __r1, __r0, __m;			\
     __d1 = __ll_highpart (d);						\
     __d0 = __ll_lowpart (d);						\
 									\
-    __r1 = (n1) % __d1;							\
     __q1 = (n1) / __d1;							\
-    __m = (UWtype) __q1 * __d0;						\
+    __r1 = (n1) - __q1 * __d1;						\
+    __m = __q1 * __d0;							\
     __r1 = __r1 * __ll_B | __ll_highpart (n0);				\
     if (__r1 < __m)							\
       {									\
 	__q1--, __r1 += (d);						\
-	if (__r1 >= (d)) /* we didn't get carry when adding to __r1 */	\
+	if (__r1 >= (d)) /* i.e. we didn't get carry when adding to __r1 */\
 	  if (__r1 < __m)						\
 	    __q1--, __r1 += (d);					\
       }									\
     __r1 -= __m;							\
 									\
-    __r0 = __r1 % __d1;							\
     __q0 = __r1 / __d1;							\
-    __m = (UWtype) __q0 * __d0;						\
+    __r0 = __r1  - __q0 * __d1;						\
+    __m = __q0 * __d0;							\
     __r0 = __r0 * __ll_B | __ll_lowpart (n0);				\
     if (__r0 < __m)							\
       {									\
@@ -344,7 +309,7 @@
       }									\
     __r0 -= __m;							\
 									\
-    (q) = (UWtype) __q1 * __ll_B | __q0;				\
+    (q) = __q1 * __ll_B | __q0;						\
     (r) = __r0;								\
   } while (0)
 
-- 
2.19.1



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