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[RFC,1/8] softfloat: Use mulu64 for mul64To128

Message ID 20201020163738.27700-2-alex.bennee@linaro.org (mailing list archive)
State New, archived
Headers show
Series fpu: experimental conversion of float128_addsub | expand

Commit Message

Alex Bennée Oct. 20, 2020, 4:37 p.m. UTC 
From: Richard Henderson <richard.henderson@linaro.org>

Via host-utils.h, we use a host widening multiply for
64-bit hosts, and a common subroutine for 32-bit hosts.

Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200925152047.709901-2-richard.henderson@linaro.org>
---
 include/fpu/softfloat-macros.h | 24 ++++--------------------
 1 file changed, 4 insertions(+), 20 deletions(-)
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Patch

diff --git a/include/fpu/softfloat-macros.h b/include/fpu/softfloat-macros.h
index a35ec2893a..57845f8af0 100644
--- a/include/fpu/softfloat-macros.h
+++ b/include/fpu/softfloat-macros.h
@@ -83,6 +83,7 @@  this code that are retained.
 #define FPU_SOFTFLOAT_MACROS_H
 
 #include "fpu/softfloat-types.h"
+#include "qemu/host-utils.h"
 
 /*----------------------------------------------------------------------------
 | Shifts `a' right by the number of bits given in `count'.  If any nonzero
@@ -515,27 +516,10 @@  static inline void
 | `z0Ptr' and `z1Ptr'.
 *----------------------------------------------------------------------------*/
 
-static inline void mul64To128( uint64_t a, uint64_t b, uint64_t *z0Ptr, uint64_t *z1Ptr )
+static inline void
+mul64To128(uint64_t a, uint64_t b, uint64_t *z0Ptr, uint64_t *z1Ptr)
 {
-    uint32_t aHigh, aLow, bHigh, bLow;
-    uint64_t z0, zMiddleA, zMiddleB, z1;
-
-    aLow = a;
-    aHigh = a>>32;
-    bLow = b;
-    bHigh = b>>32;
-    z1 = ( (uint64_t) aLow ) * bLow;
-    zMiddleA = ( (uint64_t) aLow ) * bHigh;
-    zMiddleB = ( (uint64_t) aHigh ) * bLow;
-    z0 = ( (uint64_t) aHigh ) * bHigh;
-    zMiddleA += zMiddleB;
-    z0 += ( ( (uint64_t) ( zMiddleA < zMiddleB ) )<<32 ) + ( zMiddleA>>32 );
-    zMiddleA <<= 32;
-    z1 += zMiddleA;
-    z0 += ( z1 < zMiddleA );
-    *z1Ptr = z1;
-    *z0Ptr = z0;
-
+    mulu64(z1Ptr, z0Ptr, a, b);
 }
 
 /*----------------------------------------------------------------------------