Ping 2?
> -----Original Message-----
> From: Tony Wang [mailto:tony.w...@arm.com]
> Sent: Thursday, August 28, 2014 2:02 PM
> To: 'gcc-patches@gcc.gnu.org'
> Cc: Richard Earnshaw; Ramana Radhakrishnan
> Subject: RE: [PATCH 1/3,ARM,libgcc]Code size optimization for the fmul/fdiv
> and dmul/ddiv function in libgcc
>
> Ping?
>
> > -----Original Message-----
> > From: Tony Wang [mailto:tony.w...@arm.com]
> > Sent: Thursday, August 21, 2014 2:15 PM
> > To: 'gcc-patches@gcc.gnu.org'
> > Subject: [PATCH 1/3,ARM,libgcc]Code size optimization for the fmul/fdiv and
> > dmul/ddiv function in libgcc
> >
> > Hi there,
> >
> > In libgcc the file ieee754-sf.S and ieee754-df.S have some function pairs
> > which will be bundled into one
.o file
> and
> > sharing the same .text section. For example, the fmul and fdiv, the libgcc
> > makefile will build them into
one .o
> file
> > and archived into libgcc.a. So when user only call single float point
> > multiply functions, the fdiv
function will also
> be
> > linked, and as fmul and fdiv share the same .text section, linker option
> > --gc-sections or -flot can't
remove the
> > dead code.
> >
> > So this optimization just separates the function pair(fmul/fdiv and
> > dmul/ddiv) into different sections,
following
> > the naming pattern of -ffunction-sections(.text.__functionname), through
> > which the unused sections of
> > fdiv/ddiv can be eliminated through option --gcc-sections when users only
> > use fmul/dmul.The solution is to
> add
> > a conditional statement in the macro FUNC_START, which will conditional
> > change the section of a function
> > from .text to .text.__\name. when compiling with the L_arm_muldivsf3 or
> > L_arm_muldivdf3 macro.
> >
> > GCC regression test has been done on QEMU for Cortex-M3. No new regressions
> > when turn on this patch.
> >
> > The code reduction for thumb2 on cortex-m3 is:
> > 1. When user only use single float point multiply:
> > fmul+fdiv => fmul will have a code size reduction of 318 bytes.
> >
> > 2. When user only use double float point multiply:
> > dmul+ddiv => dmul will have a code size reduction of 474 bytes.
> >
> > Ok for trunk?
> >
> > BR,
> > Tony
> >
> > Step 1: Provide another option: sp-scetion to control whether to split the
> > section of a function pair into
two
> part.
> >
> > gcc/libgcc/ChangeLog:
> > 2014-08-21 Tony Wang <tony.w...@arm.com>
> >
> > * config/arm/lib1funcs.S (FUNC_START): Add conditional section
> > redefine for macro L_arm_muldivsf3 and L_arm_muldivdf3
> > (SYM_END, ARM_SYM_START): Add macros used to expose function
> > Symbols
> >
> > diff --git a/libgcc/config/arm/lib1funcs.S b/libgcc/config/arm/lib1funcs.S
> > index b617137..0f87111 100644
> > --- a/libgcc/config/arm/lib1funcs.S
> > +++ b/libgcc/config/arm/lib1funcs.S
> > @@ -418,8 +418,12 @@ SYM (\name):
> > #define THUMB_SYNTAX
> > #endif
> >
> > -.macro FUNC_START name
> > +.macro FUNC_START name sp_section=
> > + .ifc \sp_section, function_section
> > + .section .text.__\name,"ax",%progbits
> > + .else
> > .text
> > + .endif
> > .globl SYM (__\name)
> > TYPE (__\name)
> > .align 0
> > @@ -429,14 +433,24 @@ SYM (\name):
> > SYM (__\name):
> > .endm
> >
> > +.macro ARM_SYM_START name
> > + TYPE (\name)
> > + .align 0
> > +SYM (\name):
> > +.endm
> > +
> > +.macro SYM_END name
> > + SIZE (\name)
> > +.endm
> > +
> > /* Special function that will always be coded in ARM assembly, even if
> > in Thumb-only compilation. */
> >
> > #if defined(__thumb2__)
> >
> > /* For Thumb-2 we build everything in thumb mode. */
> > -.macro ARM_FUNC_START name
> > - FUNC_START \name
> > +.macro ARM_FUNC_START name sp_section=
> > + FUNC_START \name \sp_section
> > .syntax unified
> > .endm
> > #define EQUIV .thumb_set
> > @@ -467,8 +481,12 @@ _L__\name:
> > #ifdef __ARM_ARCH_6M__
> > #define EQUIV .thumb_set
> > #else
> > -.macro ARM_FUNC_START name
> > +.macro ARM_FUNC_START name sp_section=
> > + .ifc \sp_section, function_section
> > + .section .text.__\name,"ax",%progbits
> > + .else
> > .text
> > + .endif
> > .globl SYM (__\name)
> > TYPE (__\name)
> > .align 0
