Re: [Patch, MIPS] Remove definition of TARGET_PROMOTE_PROTOTYPES

[Steve Ellcey <sellcey@imgtec.com>]

Patch ping.

Steve Ellcey
sellcey@imgtec.com


On Tue, 2015-11-10 at 15:57 -0800, Steve Ellcey wrote:
> This patch removes the definition of TARGET_PROMOTE_PROTOTYPES from MIPS,
> where it was defined as true, so that it now defaults to false.
> 
> Currently MIPS does prototype promotion in the caller and the callee and this
> patch removes the TARGET_PROMOTE_PROTOTYPES macro definition so that
> the promotion is only done in the caller (due to PROMOTE_MODE being defined).
> This does not break the ABI which requires the caller to do promotions anyway.
> (See https://gcc.gnu.org/ml/gcc/2015-10/msg00223.html).  This change also
> causes GCC to match what the LLVM and Greenhills compilers already do on MIPS.
> 
> After removing this macro I had three regressions, two were just tests that
> needed changing but one was a bug (gcc.dg/fixed-point/convert-sat.c).
> This test was calling a library function to convert a signed char into an
> unsigned fixed type and because we don't have tree type information about
> libcalls GCC cannot do the ABI required type promotion on those calls that it
> does on normal user defined calls.  In fact promote_mode in explow.c expicitly
> returns without doing anything if no type is given it.  Before this change it
> didn't matter on MIPS because the callee did the same promotion that the caller
> was supposed to have done before using the argument.  Now that callee code is
> gone we depend on the caller doing the correct promotion and that was not
> happening.
> 
> I submitted and checked in another patch to optabs.c
> (See https://gcc.gnu.org/ml/gcc-patches/2015-11/msg00704.html) to provide
> me with the infrastructure to do the correct type promotion in expand_fixed
> and this patch redefines TARGET_PROMOTE_FUNCTION_MODE to return the needed
> promotion mode even when type is NULL_TREE.  When type is set it does
> the same thing as it used to do.  This change allows me to remote the
> definition of TARGET_PROMOTE_PROTOTYPES without the convert-sat.c test
> failing.
> 
> The two tests that I changed are gcc.dg/tree-ssa/ssa-fre-4.c and
> gcc.target/mips/ext-2.c.  ssa-fre-4.c no longer applies to MIPS now
> that we do not define TARGET_PROMOTE_PROTOTYPES so I removed the MIPS
> target from it.  ext-2.c now generates an srl instruction instead of a
> dext instruction but the number of instructions has not changed and I
> updated the scan checks.
> 
> Tested on mips-mti-linux-gnu with no unfixed regressions.  OK to checkin?
> 
> Steve Ellcey
> sellcey@imgtec.com
> 
> 
> 2015-11-10  Steve Ellcey  <sellcey@imgtec.com>
> 
> 	* config/mips/mips.c (mips_promote_function_mode): New function.
> 	(TARGET_PROMOTE_FUNCTION_MODE): Define as above function.
> 	(TARGET_PROMOTE_PROTOTYPES): Remove.
> 
> 
> diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
> index 9880b23..e9c3830 100644
> --- a/gcc/config/mips/mips.c
> +++ b/gcc/config/mips/mips.c
> @@ -19760,6 +19760,32 @@ mips_ira_change_pseudo_allocno_class (int regno, reg_class_t allocno_class)
>      return GR_REGS;
>    return allocno_class;
>  }
> +
> +/* Implement TARGET_PROMOTE_FUNCTION_MODE */
> +
> +/* This function is equivalent to default_promote_function_mode_always_promote
> +   except that it returns a promoted mode even if type is NULL_TREE.  This is
> +   needed by libcalls which have no type (only a mode) such as fixed conversion
> +   routines that take a signed or unsigned char/short argument and convert it
> +   to a fixed type.  */
> +
> +static machine_mode
> +mips_promote_function_mode (const_tree type ATTRIBUTE_UNUSED,
> +                            machine_mode mode,
> +                            int *punsignedp ATTRIBUTE_UNUSED,
> +                            const_tree fntype ATTRIBUTE_UNUSED,
> +                            int for_return ATTRIBUTE_UNUSED)
> +{
> +  int unsignedp;
> +
> +  if (type != NULL_TREE)
> +    return promote_mode (type, mode, punsignedp);
> +
> +  unsignedp = *punsignedp;
> +  PROMOTE_MODE (mode, unsignedp, type);
> +  *punsignedp = unsignedp;
> +  return mode;
> +}
>  \f
>  /* Initialize the GCC target structure.  */
>  #undef TARGET_ASM_ALIGNED_HI_OP
> @@ -19864,10 +19890,7 @@ mips_ira_change_pseudo_allocno_class (int regno, reg_class_t allocno_class)
>  #define TARGET_GIMPLIFY_VA_ARG_EXPR mips_gimplify_va_arg_expr
>  
>  #undef  TARGET_PROMOTE_FUNCTION_MODE
> -#define TARGET_PROMOTE_FUNCTION_MODE default_promote_function_mode_always_promote
> -#undef TARGET_PROMOTE_PROTOTYPES
> -#define TARGET_PROMOTE_PROTOTYPES hook_bool_const_tree_true
> -
> +#define TARGET_PROMOTE_FUNCTION_MODE mips_promote_function_mode
>  #undef TARGET_FUNCTION_VALUE
>  #define TARGET_FUNCTION_VALUE mips_function_value
>  #undef TARGET_LIBCALL_VALUE
> 
> 
> 
> 
> 2015-11-10  Steve Ellcey  <sellcey@imgtec.com>
> 
> 	* gcc.dg/tree-ssa/ssa-fre-4.c: Remove mips*-*-* target.
> 	* gcc.target/mips/ext-2.c: Update scan checks.
> 
> 
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-4.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-4.c
> index 02b6719..5a7588f 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-4.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-4.c
> @@ -1,6 +1,6 @@
>  /* If the target returns false for TARGET_PROMOTE_PROTOTYPES, then there
>     will be no casts for FRE to eliminate and the test will fail.  */
> -/* { dg-do compile { target i?86-*-* x86_64-*-* hppa*-*-* mips*-*-* m68k*-*-* } } */
> +/* { dg-do compile { target i?86-*-* x86_64-*-* hppa*-*-* m68k*-*-* } } */
>  /* { dg-options "-O -fno-tree-ccp -fno-tree-forwprop -fdump-tree-fre1-details" } */
>  
>  /* From PR21608.  */
> diff --git a/gcc/testsuite/gcc.target/mips/ext-2.c b/gcc/testsuite/gcc.target/mips/ext-2.c
> index 320d42d..9770321 100644
> --- a/gcc/testsuite/gcc.target/mips/ext-2.c
> +++ b/gcc/testsuite/gcc.target/mips/ext-2.c
> @@ -1,12 +1,13 @@
>  /* Turn the truncate,zero_extend,lshiftrt sequence before the or into a
>     zero_extract.  The truncate is due to TARGET_PROMOTE_PROTOTYPES, the
> -   zero_extend to PROMOTE_MODE.  */
> +   zero_extend to PROMOTE_MODE.  As of GCC 6, we no longer define
> +   TARGET_PROMOTE_PROTOTYPES so that truncate is gone and we can
> +   generate either a single extract or a single shift instruction.  */
>  /* { dg-do compile } */
>  /* { dg-options "isa_rev>=2 -mgp64 -mlong64" } */
>  /* { dg-skip-if "code quality test" { *-*-* } { "-O0" } { "" } } */
> -/* { dg-final { scan-assembler "\tdext\t" } } */
> +/* { dg-final { scan-assembler-times "\tdext\t|\td?srl" 1 } } */
>  /* { dg-final { scan-assembler-not "\tand" } } */
> -/* { dg-final { scan-assembler-not "\td?srl" } } */
>  
>  NOMIPS16 void
>  f (unsigned char x, unsigned char *r)