Date: Fri, 6 Sep 2019 12:45:03 +0200 From: "Stefan Kanthak" <stefan.kanthak@nexgo.de> To: <freebsd-numerics@freebsd.org> Cc: <das@FreeBSD.ORG> Subject: Superfluous instructions in crufty old releng/12.0/lib/msun/i387/s_remquo.S, releng/12.0/lib/msun/amd64/s_remquo.S, ... Message-ID: <582553CAF6B647A09A15C24F50B9A75E@H270>
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Hi, although I doubt that this FPU code might still be used, here's a patch to shave 2 superfluous instructions from http://sources.freebsd.org/releng/12.0/lib/msun/i387/s_remquo.S http://sources.freebsd.org/releng/12.0/lib/msun/i387/s_remquof.S http://sources.freebsd.org/releng/12.0/lib/msun/i387/s_remquol.S http://sources.freebsd.org/releng/12.0/lib/msun/amd64/s_remquo.S http://sources.freebsd.org/releng/12.0/lib/msun/amd64/s_remquof.S http://sources.freebsd.org/releng/12.0/lib/msun/amd64/s_remquol.S regards Stefan Kanthak --- -/releng/12.0/lib/msun/i387/s_remquo.S +++ +/releng/12.0/lib/msun/i387/s_remquo.S @@ -51,8 +51,6 @@ /* Negate the quotient bits if x*y<0. Avoid using an unpredictable branch. */ movl 16(%esp),%ecx xorl 8(%esp),%ecx - sarl $16,%ecx - sarl $16,%ecx + sarl $31,%ecx xorl %ecx,%eax - andl $1,%ecx - addl %ecx,%eax + subl %ecx,%eax --- -/releng/12.0/lib/msun/i387/s_remquof.S +++ +/releng/12.0/lib/msun/i387/s_remquof.S @@ -51,8 +51,6 @@ /* Negate the quotient bits if x*y<0. Avoid using an unpredictable branch. */ movl 8(%esp),%ecx xorl 4(%esp),%ecx - sarl $16,%ecx - sarl $16,%ecx + sarl $31,%ecx xorl %ecx,%eax - andl $1,%ecx - addl %ecx,%eax + subl %ecx,%eax --- -/releng/12.0/lib/msun/i387/s_remquol.S +++ +/releng/12.0/lib/msun/i387/s_remquol.S @@ -51,9 +51,7 @@ /* Negate the quotient bits if x*y<0. Avoid using an unpredictable branch. */ movl 24(%esp),%ecx xorl 12(%esp),%ecx movsx %cx,%ecx sarl $16,%ecx - sarl $16,%ecx xorl %ecx,%eax - andl $1,%ecx - addl %ecx,%eax + subl %ecx,%eax --- -/releng/12.0/lib/msun/amd64/s_remquo.S --- +/releng/12.0/lib/msun/amd64/s_remquo.S @@ -53,8 +53,6 @@ /* Negate the quotient bits if x*y<0. Avoid using an unpredictable branch. */ movl -12(%rsp),%ecx xorl -4(%rsp),%ecx - sarl $16,%ecx - sarl $16,%ecx + sarl $31,%ecx xorl %ecx,%eax - andl $1,%ecx - addl %ecx,%eax + subl %ecx,%eax --- -/releng/12.0/lib/msun/amd64/s_remquof.S --- +/releng/12.0/lib/msun/amd64/s_remquof.S @@ -53,8 +53,6 @@ /* Negate the quotient bits if x*y<0. Avoid using an unpredictable branch. */ movl -8(%rsp),%ecx xorl -4(%rsp),%ecx - sarl $16,%ecx - sarl $16,%ecx + sarl $31,%ecx xorl %ecx,%eax - andl $1,%ecx - addl %ecx,%eax + subl %ecx,%eax --- -/releng/12.0/lib/msun/amd64/s_remquol.S --- +/releng/12.0/lib/msun/amd64/s_remquol.S @@ -51,9 +51,6 @@ /* Negate the quotient bits if x*y<0. Avoid using an unpredictable branch. */ movl 32(%rsp),%ecx xorl 16(%rsp),%ecx movsx %cx,%ecx sarl $16,%ecx - sarl $16,%ecx xorl %ecx,%eax - andl $1,%ecx - addl %ecx,%eax + subl %ecx,%eax
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