Re: [PATCH] PR libgcc/83112, Fix warnings on libgcc float128-ifunc.c

[Michael Meissner <meissner@linux.vnet.ibm.com>]

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On Mon, Nov 27, 2017 at 03:40:58PM -0700, Martin Sebor wrote:
> On 11/27/2017 12:21 PM, Michael Meissner wrote:
> >The new -Wattribute-alias option now issues warnings for old-style ifunc
> >declarations that coerce the pointer to the function to void *.  The
> >float128-ifunc.c module in libgcc/config/rs6000 now gets a lot of warnings of
> >the form:
> >
> >../float128-ifunc.c:109:1: warning: ‘ifunc’ resolver for ‘__negkf2’ should
> >return ‘TFtype (*)(TFtype) {aka _Float128 (*)(_Float128)}’ [-Wattribute-alias]
> >
> >This patch fixes these warnings.  I have done a full bootstrap build and test
> >suite run.  I have verified that the ifunc handler works correctly, using
> >software emulation on a power8 and the hardware instructions on power9.  Can I
> >check this into the trunk?
> 
> Just as a side note, a convenient way to deal with this is to use
> typeof to deduce the return type of the resolver from the type of
> the function it returns.  I would expect something like
> the following untested change to do it and make the typedefs
> unnecessary:
> 
>   -static void *
>   +static __typeof__ (__addkf3_sw) *
>    __addkf3_resolve (void)
>    {
>   -  return (void *) SW_OR_HW (__addkf3_sw, __addkf3_hw);
>   +  return SW_OR_HW (__addkf3_sw, __addkf3_hw);
>    }
> 
> Martin

Thanks, that does simplify things.  I redid the patch for both PR libgcc/83112
(avoid the warnings in float128-ifunc) and PR libgcc/83103 (optimize complex
float128 multiply/divide when running on ISA 3.0 hardware).

This patch combines both PRs.  I have bootstrapped it and done a regression
test with no regressions.  Can I install this patch in the trunk?

2017-11-27  Michael Meissner  <meissner@linux.vnet.ibm.com>

	PR libgcc/83112
	* config/rs6000/float128-ifunc.c (__addkf3_resolve): Use the
	correct type for all ifunc resolvers to silence -Wattribute-alias
	warnings.  Eliminate the forward declaration of the resolver
	functions which is no longer needed.
	(__subkf3_resolve): Likewise.
	(__mulkf3_resolve): Likewise.
	(__divkf3_resolve): Likewise.
	(__negkf2_resolve): Likewise.
	(__eqkf2_resolve): Likewise.
	(__nekf2_resolve): Likewise.
	(__gekf2_resolve): Likewise.
	(__gtkf2_resolve): Likewise.
	(__lekf2_resolve): Likewise.
	(__ltkf2_resolve): Likewise.
	(__unordkf2_resolve): Likewise.
	(__extendsfkf2_resolve): Likewise.
	(__extenddfkf2_resolve): Likewise.
	(__trunckfsf2_resolve): Likewise.
	(__trunckfdf2_resolve): Likewise.
	(__fixkfsi_resolve): Likewise.
	(__fixkfdi_resolve): Likewise.
	(__fixunskfsi_resolve): Likewise.
	(__fixunskfdi_resolve): Likewise.
	(__floatsikf_resolve): Likewise.
	(__floatdikf_resolve): Likewise.
	(__floatunsikf_resolve): Likewise.
	(__floatundikf_resolve): Likewise.
	(__extendkftf2_resolve): Likewise.
	(__trunctfkf2_resolve): Likewise.

	PR libgcc/83103
	* config/rs6000/quad-float128.h (TF): Don't define if long double
	is IEEE 128-bit floating point.
	(TCtype): Define as either TCmode or KCmode, depending on whether
	long double is IEEE 128-bit floating point.
	(__mulkc3_sw): Add declarations for software/hardware versions of
	complex multiply/divide.
	(__divkc3_sw): Likewise.
	(__mulkc3_hw): Likewise.
	(__divkc3_hw): Likewise.
	* config/rs6000/_mulkc3.c (_mulkc3): If we are building ifunc
	handlers to switch between using software emulation and hardware
	float128 instructions, build the complex multiply/divide functions
	for both software and hardware support.
	* config/rs6000/_divkc3.c (_divkc3): Likewise.
	* config/rs6000/float128-ifunc.c (__mulkc3_resolve): Likewise.
	(__divkc3_resolve): Likewise.
	(__mulkc3): Likewise.
	(__divkc3): Likewise.
	* config/rs6000/t-float128-hw (fp128_hardfp_src): Likewise.
	(fp128_hw_src): Likewise.
	(fp128_hw_static_obj): Likewise.
	(fp128_hw_shared_obj): Likewise.
	(_mulkc3-hw.c): Likewise.
	(_divkc3-hw.c): Likewise.
	* config/rs6000/t-float128 (clean-float128): Delete _mulkc3-hw.c
	and _divkc3-hw.c.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.vnet.ibm.com, phone: +1 (978) 899-4797

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Index: libgcc/config/rs6000/quad-float128.h
===================================================================
--- libgcc/config/rs6000/quad-float128.h	(revision 255177)
+++ libgcc/config/rs6000/quad-float128.h	(working copy)
@@ -30,13 +30,20 @@
 /* quad.h defines the TFtype type by:
    typedef float TFtype __attribute__ ((mode (TF)));
 
-   This define forces it to use KFmode (aka, ieee 128-bit floating point).  */
+   This define forces it to use KFmode (aka, ieee 128-bit floating point).
+   However, when the compiler's default is changed so that long double is IEEE
+   128-bit floating point, we need to go back to using TFmode and TCmode.  */
+#ifndef __LONG_DOUBLE_IEEE128__
 #define TF KF
 
 /* We also need TCtype to represent complex ieee 128-bit float for
    __mulkc3 and __divkc3.  */
 typedef __complex float TCtype __attribute__ ((mode (KC)));
 
+#else
+typedef __complex float TCtype __attribute__ ((mode (TC)));
+#endif
+
 /* Force the use of the VSX instruction set.  */
 #if defined(_ARCH_PPC) && (!defined(__VSX__) || !defined(__FLOAT128__))
 #pragma GCC target ("vsx,float128")
@@ -88,6 +95,8 @@ extern TFtype __floatunsikf_sw (USItype_
 extern TFtype __floatundikf_sw (UDItype_ppc);
 extern IBM128_TYPE __extendkftf2_sw (TFtype);
 extern TFtype __trunctfkf2_sw (IBM128_TYPE);
+extern TCtype __mulkc3_sw (TFtype, TFtype, TFtype, TFtype);
+extern TCtype __divkc3_sw (TFtype, TFtype, TFtype, TFtype);
 
 #ifdef _ARCH_PPC64
 /* We do not provide ifunc resolvers for __fixkfti, __fixunskfti, __floattikf,
@@ -128,6 +137,8 @@ extern TFtype __floatunsikf_hw (USItype_
 extern TFtype __floatundikf_hw (UDItype_ppc);
 extern IBM128_TYPE __extendkftf2_hw (TFtype);
 extern TFtype __trunctfkf2_hw (IBM128_TYPE);
+extern TCtype __mulkc3_hw (TFtype, TFtype, TFtype, TFtype);
+extern TCtype __divkc3_hw (TFtype, TFtype, TFtype, TFtype);
 
 /* Ifunc function declarations, to automatically switch between software
    emulation and hardware support.  */
Index: libgcc/config/rs6000/_mulkc3.c
===================================================================
--- libgcc/config/rs6000/_mulkc3.c	(revision 255177)
+++ libgcc/config/rs6000/_mulkc3.c	(working copy)
@@ -31,6 +31,10 @@ typedef __complex float KCtype __attribu
 #define isnan __builtin_isnan
 #define isinf __builtin_isinf
 
+#if defined(FLOAT128_HW_INSNS) && !defined(__mulkc3)
+#define __mulkc3 __mulkc3_sw
+#endif
+
 KCtype
 __mulkc3 (KFtype a, KFtype b, KFtype c, KFtype d)
 {
Index: libgcc/config/rs6000/_divkc3.c
===================================================================
--- libgcc/config/rs6000/_divkc3.c	(revision 255177)
+++ libgcc/config/rs6000/_divkc3.c	(working copy)
@@ -33,6 +33,10 @@ typedef __complex float KCtype __attribu
 #define isinf __builtin_isinf
 #define isfinite __builtin_isfinite
 
+#if defined(FLOAT128_HW_INSNS) && !defined(__divkc3)
+#define __divkc3 __divkc3_sw
+#endif
+
 KCtype
 __divkc3 (KFtype a, KFtype b, KFtype c, KFtype d)
 {
Index: libgcc/config/rs6000/float128-ifunc.c
===================================================================
--- libgcc/config/rs6000/float128-ifunc.c	(revision 255177)
+++ libgcc/config/rs6000/float128-ifunc.c	(working copy)
@@ -54,190 +54,175 @@
    128-bit integer types and 128-bit IEEE floating point, or vice versa.  So
    use the emulator functions for these conversions.  */
 
-static void *__addkf3_resolve (void);
-static void *__subkf3_resolve (void);
-static void *__mulkf3_resolve (void);
-static void *__divkf3_resolve (void);
-static void *__negkf2_resolve (void);
-static void *__eqkf2_resolve (void);
-static void *__nekf2_resolve (void);
-static void *__gekf2_resolve (void);
-static void *__gtkf2_resolve (void);
-static void *__lekf2_resolve (void);
-static void *__ltkf2_resolve (void);
-static void *__unordkf2_resolve (void);
-static void *__extendsfkf2_resolve (void);
-static void *__extenddfkf2_resolve (void);
-static void *__trunckfsf2_resolve (void);
-static void *__trunckfdf2_resolve (void);
-static void *__fixkfsi_resolve (void);
-static void *__fixkfdi_resolve (void);
-static void *__fixunskfsi_resolve (void);
-static void *__fixunskfdi_resolve (void);
-static void *__floatsikf_resolve (void);
-static void *__floatdikf_resolve (void);
-static void *__floatunsikf_resolve (void);
-static void *__floatundikf_resolve (void);
-static void *__extendkftf2_resolve (void);
-static void *__trunctfkf2_resolve (void);
-
-static void *
+static __typeof__ (__addkf3_sw) *
 __addkf3_resolve (void)
 {
-  return (void *) SW_OR_HW (__addkf3_sw, __addkf3_hw);
+  return SW_OR_HW (__addkf3_sw, __addkf3_hw);
 }
 
-static void *
+static __typeof__ (__subkf3_sw) *
 __subkf3_resolve (void)
 {
-  return (void *) SW_OR_HW (__subkf3_sw, __subkf3_hw);
+  return SW_OR_HW (__subkf3_sw, __subkf3_hw);
 }
 
-static void *
+static __typeof__ (__mulkf3_sw) *
 __mulkf3_resolve (void)
 {
-  return (void *) SW_OR_HW (__mulkf3_sw, __mulkf3_hw);
+  return SW_OR_HW (__mulkf3_sw, __mulkf3_hw);
 }
 
-static void *
+static __typeof__ (__divkf3_sw) *
 __divkf3_resolve (void)
 {
-  return (void *) SW_OR_HW (__divkf3_sw, __divkf3_hw);
+  return SW_OR_HW (__divkf3_sw, __divkf3_hw);
 }
 
-static void *
+static __typeof__ (__negkf2_sw) *
 __negkf2_resolve (void)
 {
-  return (void *) SW_OR_HW (__negkf2_sw, __negkf2_hw);
+  return SW_OR_HW (__negkf2_sw, __negkf2_hw);
 }
 
-static void *
+static __typeof__ (__floatsikf_sw) *
 __floatsikf_resolve (void)
 {
-  return (void *) SW_OR_HW (__floatsikf_sw, __floatsikf_hw);
+  return SW_OR_HW (__floatsikf_sw, __floatsikf_hw);
 }
 
-static void *
+static __typeof__ (__floatdikf_sw) *
 __floatdikf_resolve (void)
 {
-  return (void *) SW_OR_HW (__floatdikf_sw, __floatdikf_hw);
+  return SW_OR_HW (__floatdikf_sw, __floatdikf_hw);
 }
 
-static void *
+static __typeof__ (__floatunsikf_sw) *
 __floatunsikf_resolve (void)
 {
-  return (void *) SW_OR_HW (__floatunsikf_sw, __floatunsikf_hw);
+  return SW_OR_HW (__floatunsikf_sw, __floatunsikf_hw);
 }
 
-static void *
+static __typeof__ (__floatundikf_sw) *
 __floatundikf_resolve (void)
 {
-  return (void *) SW_OR_HW (__floatundikf_sw, __floatundikf_hw);
+  return SW_OR_HW (__floatundikf_sw, __floatundikf_hw);
 }
 
-static void *
+static __typeof__ (__fixkfsi_sw) *
 __fixkfsi_resolve (void)
 {
-  return (void *) SW_OR_HW (__fixkfsi_sw, __fixkfsi_hw);
+  return SW_OR_HW (__fixkfsi_sw, __fixkfsi_hw);
 }
 
-static void *
+static __typeof__ (__fixkfdi_sw) *
 __fixkfdi_resolve (void)
 {
-  return (void *) SW_OR_HW (__fixkfdi_sw, __fixkfdi_hw);
+  return SW_OR_HW (__fixkfdi_sw, __fixkfdi_hw);
 }
 
-static void *
+static __typeof__ (__fixunskfsi_sw) *
 __fixunskfsi_resolve (void)
 {
-  return (void *) SW_OR_HW (__fixunskfsi_sw, __fixunskfsi_hw);
+  return SW_OR_HW (__fixunskfsi_sw, __fixunskfsi_hw);
 }
 
-static void *
+static __typeof__ (__fixunskfdi_sw) *
 __fixunskfdi_resolve (void)
 {
-  return (void *) SW_OR_HW (__fixunskfdi_sw, __fixunskfdi_hw);
+  return SW_OR_HW (__fixunskfdi_sw, __fixunskfdi_hw);
 }
 
-static void *
+static __typeof__ (__extendsfkf2_sw) *
 __extendsfkf2_resolve (void)
 {
-  return (void *) SW_OR_HW (__extendsfkf2_sw, __extendsfkf2_hw);
+  return SW_OR_HW (__extendsfkf2_sw, __extendsfkf2_hw);
 }
 
-static void *
+static __typeof__ (__extenddfkf2_sw) *
 __extenddfkf2_resolve (void)
 {
-  return (void *) SW_OR_HW (__extenddfkf2_sw, __extenddfkf2_hw);
+  return SW_OR_HW (__extenddfkf2_sw, __extenddfkf2_hw);
 }
 
-static void *
+static __typeof__ (__trunckfsf2_sw) *
 __trunckfsf2_resolve (void)
 {
-  return (void *) SW_OR_HW (__trunckfsf2_sw, __trunckfsf2_hw);
+  return SW_OR_HW (__trunckfsf2_sw, __trunckfsf2_hw);
 }
 
-static void *
+static __typeof__ (__trunckfdf2_sw) *
 __trunckfdf2_resolve (void)
 {
   return (void *) SW_OR_HW (__trunckfdf2_sw, __trunckfdf2_hw);
 }
 
-static void *
+static __typeof__ (__extendkftf2_sw) *
 __extendkftf2_resolve (void)
 {
-  return (void *) SW_OR_HW (__extendkftf2_sw, __extendkftf2_hw);
+  return SW_OR_HW (__extendkftf2_sw, __extendkftf2_hw);
 }
 
-static void *
+static __typeof__ (__trunctfkf2_sw) *
 __trunctfkf2_resolve (void)
 {
-  return (void *) SW_OR_HW (__trunctfkf2_sw, __trunctfkf2_hw);
+  return SW_OR_HW (__trunctfkf2_sw, __trunctfkf2_hw);
 }
 
-static void *
+static __typeof__ (__mulkc3_sw) *
+__mulkc3_resolve (void)
+{
+  return SW_OR_HW (__mulkc3_sw, __mulkc3_hw);
+}
+
+static __typeof__ (__divkc3_sw) *
+__divkc3_resolve (void)
+{
+  return SW_OR_HW (__divkc3_sw, __divkc3_hw);
+}
+
+static __typeof__ (__eqkf2_sw) *
 __eqkf2_resolve (void)
 {
-  return (void *) SW_OR_HW (__eqkf2_sw, __eqkf2_hw);
+  return SW_OR_HW (__eqkf2_sw, __eqkf2_hw);
 }
 
-static void *
+static __typeof__ (__gekf2_sw) *
 __gekf2_resolve (void)
 {
-  return (void *) SW_OR_HW (__gekf2_sw, __gekf2_hw);
+  return SW_OR_HW (__gekf2_sw, __gekf2_hw);
 }
 
-static void *
+static __typeof__ (__lekf2_sw) *
 __lekf2_resolve (void)
 {
-  return (void *) SW_OR_HW (__lekf2_sw, __lekf2_hw);
+  return SW_OR_HW (__lekf2_sw, __lekf2_hw);
 }
 
-static void *
+static __typeof__ (__unordkf2_sw) *
 __unordkf2_resolve (void)
 {
-  return (void *) SW_OR_HW (__unordkf2_sw, __unordkf2_hw);
+  return SW_OR_HW (__unordkf2_sw, __unordkf2_hw);
 }
 
 /* Resolve __nekf2, __gtkf2, __ltkf2 like __eqkf2, __gekf2, and __lekf2, since
    the functions return the same values.  */
 
-static void *
+static __typeof__ (__eqkf2_sw) *
 __nekf2_resolve (void)
 {
-  return (void *) SW_OR_HW (__eqkf2_sw, __eqkf2_hw);
+  return SW_OR_HW (__eqkf2_sw, __eqkf2_hw);
 }
 
-static void *
+static __typeof__ (__eqkf2_sw) *
 __gtkf2_resolve (void)
 {
-  return (void *) SW_OR_HW (__gekf2_sw, __gekf2_hw);
+  return SW_OR_HW (__gekf2_sw, __gekf2_hw);
 }
 
-static void *
+static __typeof__ (__eqkf2_sw) *
 __ltkf2_resolve (void)
 {
-  return (void *) SW_OR_HW (__lekf2_sw, __lekf2_hw);
+  return SW_OR_HW (__lekf2_sw, __lekf2_hw);
 }
 
 
@@ -320,3 +305,9 @@ IBM128_TYPE __extendkftf2 (TFtype)
 
 TFtype __trunctfkf2 (IBM128_TYPE)
   __attribute__ ((__ifunc__ ("__trunctfkf2_resolve")));
+
+TCtype __mulkc3 (TFtype, TFtype, TFtype, TFtype)
+  __attribute__ ((__ifunc__ ("__mulkc3_resolve")));
+
+TCtype __divkc3 (TFtype, TFtype, TFtype, TFtype)
+  __attribute__ ((__ifunc__ ("__divkc3_resolve")));
Index: libgcc/config/rs6000/t-float128-hw
===================================================================
--- libgcc/config/rs6000/t-float128-hw	(revision 255177)
+++ libgcc/config/rs6000/t-float128-hw	(working copy)
@@ -5,10 +5,12 @@
 FLOAT128_HW_INSNS	= -DFLOAT128_HW_INSNS
 
 # New functions for hardware support
-fp128_hw_funcs		= float128-hw
-fp128_hw_src		= $(srcdir)/config/rs6000/float128-hw.c
-fp128_hw_static_obj	= float128-hw$(objext)
-fp128_hw_shared_obj	= float128-hw_s$(objext)
+fp128_hardfp_src	= _mulkc3-hw.c _divkc3-hw.c
+fp128_hw_funcs		= float128-hw _mulkc3-hw _divkc3-hw
+fp128_hw_src		= $(srcdir)/config/rs6000/float128-hw.c _mulkc3-hw.c \
+			  _divkc3-hw.c
+fp128_hw_static_obj	= $(addsuffix $(objext),$(fp128_hw_funcs))
+fp128_hw_shared_obj	= $(addsuffix _s$(objext),$(fp128_hw_funcs))
 fp128_hw_obj		= $(fp128_hw_static_obj) $(fp128_hw_shared_obj)
 
 fp128_ifunc_funcs	= float128-ifunc
@@ -33,3 +35,13 @@ $(fp128_hw_obj)		 : $(srcdir)/config/rs6
 
 $(fp128_ifunc_obj)	 : INTERNAL_CFLAGS += $(FP128_CFLAGS_SW)
 $(fp128_ifunc_obj)	 : $(srcdir)/config/rs6000/t-float128-hw
+
+_mulkc3-hw.c: $(srcdir)/config/rs6000/_mulkc3.c
+	rm -rf _mulkc3.c
+	(echo "#define __mulkc3 __mulkc3_hw"; \
+	 cat $(srcdir)/config/rs6000/_mulkc3.c) > _mulkc3-hw.c
+
+_divkc3-hw.c: $(srcdir)/config/rs6000/_divkc3.c
+	rm -rf _divkc3.c
+	(echo "#define __divkc3 __divkc3_hw"; \
+	 cat $(srcdir)/config/rs6000/_divkc3.c) > _divkc3-hw.c
Index: libgcc/config/rs6000/t-float128
===================================================================
--- libgcc/config/rs6000/t-float128	(revision 255177)
+++ libgcc/config/rs6000/t-float128	(working copy)
@@ -86,7 +86,7 @@ test:
 	for x in $(fp128_obj); do echo "    $$x"; done;
 
 clean-float128:
-	rm -rf $(fp128_softfp_src)
+	rm -rf $(fp128_softfp_src) $(fp128_hardfp_src)
 	@$(MULTICLEAN) multi-clean DO=clean-float128
 
 # For now, only put it in the static library