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Re: [PATCH, rs6000] Fold vector shifts in GIMPLE
On Wed, Jun 7, 2017 at 4:14 PM, Bill Schmidt
<wschmidt@linux.vnet.ibm.com> wrote:
>
>> On Jun 6, 2017, at 11:37 AM, Will Schmidt <will_schmidt@vnet.ibm.com> wrote:
>>
>> On Thu, 2017-06-01 at 10:15 -0500, Bill Schmidt wrote:
>>>> On Jun 1, 2017, at 2:48 AM, Richard Biener <richard.guenther@gmail.com> wrote:
>>>>
>>>> On Wed, May 31, 2017 at 10:01 PM, Will Schmidt
>>>> <will_schmidt@vnet.ibm.com> wrote:
>>>>> Hi,
>>>>>
>>>>> Add support for early expansion of vector shifts. Including
>>>>> vec_sl (shift left), vec_sr (shift right), vec_sra (shift
>>>>> right algebraic), vec_rl (rotate left).
>>>>> Part of this includes adding the vector shift right instructions to
>>>>> the list of those instructions having an unsigned second argument.
>>>>>
>>>>> The VSR (vector shift right) folding is a bit more complex than
>>>>> the others. This is due to requiring arg0 be unsigned for an algebraic
>>>>> shift before the gimple RSHIFT_EXPR assignment is built.
>>>>
>>>> Jakub, do we sanitize that undefinedness of left shifts of negative values
>>>> and/or overflow of left shift of nonnegative values?
>>
>>
>> On Thu, 2017-06-01 at 10:17 +0200, Jakub Jelinek wrote:
>>> We don't yet, see PR77823 - all I've managed to do before stage1 was over
>>> was instrumentation of signed arithmetic integer overflow on vectors,
>>> division, shift etc. are tasks maybe for this stage1.
>>>
>>> That said, shift instrumentation in particular is done early because every
>>> FE has different rules, and so if it is coming from target builtins that are
>>> folded into something, it wouldn't be instrumented anyway.
>>
>>
>> On Thu, 2017-06-01 at 10:15 -0500, Bill Schmidt wrote:
>>>>
>>>> Will, how is that defined in the intrinsics operation? It might need similar
>>>> treatment as the abs case.
>>>
>>> Answering for Will -- vec_sl is defined to simply shift bits off the end to the
>>> left and fill with zeros from the right, regardless of whether the source type
>>> is signed or unsigned. The result type is signed iff the source type is
>>> signed. So a negative value can become positive as a result of the
>>> operation.
>>>
>>> The same is true of vec_rl, which will naturally rotate bits regardless of
>>> signedness.
>>
>>
>>>>
>>>> [I'd rather make the negative left shift case implementation defined
>>>> given C and C++ standards
>>>> do not agree to 100% AFAIK]
>>
>> With the above answers, how does this one stand?
>>
>> [ I have no issue adding the TYPE_OVERFLOW_WRAPS logic to treat some of
>> the cases differently, I'm just unclear on whether none/some/all of the
>> shifts will require that logic. :-) ]
>
> I have to defer to Richard here, I don't know the subtleties well enough.
I'd say play safe and guard folding of left shifts with TYPE_OVERFLOW_WRAPS.
Richard.
> Bill
>
>>
>> thanks,
>> -Will
>>
>>
>>
>>
>>>>
>>>> Richard.
>>>>
>>>>> [gcc]
>>>>>
>>>>> 2017-05-26 Will Schmidt <will_schmidt@vnet.ibm.com>
>>>>>
>>>>> * config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): Add handling
>>>>> for early expansion of vector shifts (sl,sr,sra,rl).
>>>>> (builtin_function_type): Add vector shift right instructions
>>>>> to the unsigned argument list.
>>>>>
>>>>> [gcc/testsuite]
>>>>>
>>>>> 2017-05-26 Will Schmidt <will_schmidt@vnet.ibm.com>
>>>>>
>>>>> * testsuite/gcc.target/powerpc/fold-vec-shift-char.c: New.
>>>>> * testsuite/gcc.target/powerpc/fold-vec-shift-int.c: New.
>>>>> * testsuite/gcc.target/powerpc/fold-vec-shift-longlong.c: New.
>>>>> * testsuite/gcc.target/powerpc/fold-vec-shift-short.c: New.
>>>>>
>>>>> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
>>>>> index 8adbc06..6ee0bfd 100644
>>>>> --- a/gcc/config/rs6000/rs6000.c
>>>>> +++ b/gcc/config/rs6000/rs6000.c
>>>>> @@ -17408,6 +17408,76 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi)
>>>>> gsi_replace (gsi, g, true);
>>>>> return true;
>>>>> }
>>>>> + /* Flavors of vec_rotate_left . */
>>>>> + case ALTIVEC_BUILTIN_VRLB:
>>>>> + case ALTIVEC_BUILTIN_VRLH:
>>>>> + case ALTIVEC_BUILTIN_VRLW:
>>>>> + case P8V_BUILTIN_VRLD:
>>>>> + {
>>>>> + arg0 = gimple_call_arg (stmt, 0);
>>>>> + arg1 = gimple_call_arg (stmt, 1);
>>>>> + lhs = gimple_call_lhs (stmt);
>>>>> + gimple *g = gimple_build_assign (lhs, LROTATE_EXPR, arg0, arg1);
>>>>> + gimple_set_location (g, gimple_location (stmt));
>>>>> + gsi_replace (gsi, g, true);
>>>>> + return true;
>>>>> + }
>>>>> + /* Flavors of vector shift right algebraic. vec_sra{b,h,w} -> vsra{b,h,w}. */
>>>>> + case ALTIVEC_BUILTIN_VSRAB:
>>>>> + case ALTIVEC_BUILTIN_VSRAH:
>>>>> + case ALTIVEC_BUILTIN_VSRAW:
>>>>> + case P8V_BUILTIN_VSRAD:
>>>>> + {
>>>>> + arg0 = gimple_call_arg (stmt, 0);
>>>>> + arg1 = gimple_call_arg (stmt, 1);
>>>>> + lhs = gimple_call_lhs (stmt);
>>>>> + gimple *g = gimple_build_assign (lhs, RSHIFT_EXPR, arg0, arg1);
>>>>> + gimple_set_location (g, gimple_location (stmt));
>>>>> + gsi_replace (gsi, g, true);
>>>>> + return true;
>>>>> + }
>>>>> + /* Flavors of vector shift left. builtin_altivec_vsl{b,h,w} -> vsl{b,h,w}. */
>>>>> + case ALTIVEC_BUILTIN_VSLB:
>>>>> + case ALTIVEC_BUILTIN_VSLH:
>>>>> + case ALTIVEC_BUILTIN_VSLW:
>>>>> + case P8V_BUILTIN_VSLD:
>>>>> + {
>>>>> + arg0 = gimple_call_arg (stmt, 0);
>>>>> + arg1 = gimple_call_arg (stmt, 1);
>>>>> + lhs = gimple_call_lhs (stmt);
>>>>> + gimple *g = gimple_build_assign (lhs, LSHIFT_EXPR, arg0, arg1);
>>>>> + gimple_set_location (g, gimple_location (stmt));
>>>>> + gsi_replace (gsi, g, true);
>>>>> + return true;
>>>>> + }
>>>>> + /* Flavors of vector shift right. */
>>>>> + case ALTIVEC_BUILTIN_VSRB:
>>>>> + case ALTIVEC_BUILTIN_VSRH:
>>>>> + case ALTIVEC_BUILTIN_VSRW:
>>>>> + case P8V_BUILTIN_VSRD:
>>>>> + {
>>>>> + arg0 = gimple_call_arg (stmt, 0);
>>>>> + arg1 = gimple_call_arg (stmt, 1);
>>>>> + lhs = gimple_call_lhs (stmt);
>>>>> + gimple *g;
>>>>> + /* convert arg0 to unsigned */
>>>>> + arg0 = convert(unsigned_type_for(TREE_TYPE(arg0)),arg0);
>>>>> + tree arg0_uns = create_tmp_reg_or_ssa_name(unsigned_type_for(TREE_TYPE(arg0)));
>>>>> + g = gimple_build_assign(arg0_uns,arg0);
>>>>> + gimple_set_location (g, gimple_location (stmt));
>>>>> + gsi_insert_before (gsi, g, GSI_SAME_STMT);
>>>>> + /* convert lhs to unsigned and do the shift. */
>>>>> + tree lhs_uns = create_tmp_reg_or_ssa_name(unsigned_type_for(TREE_TYPE(lhs)));
>>>>> + g = gimple_build_assign (lhs_uns, RSHIFT_EXPR, arg0_uns, arg1);
>>>>> + gimple_set_location (g, gimple_location (stmt));
>>>>> + gsi_insert_before (gsi, g, GSI_SAME_STMT);
>>>>> + /* convert lhs back to a signed type for the return. */
>>>>> + lhs_uns = convert(signed_type_for(TREE_TYPE(lhs)),lhs_uns);
>>>>> + g = gimple_build_assign(lhs,lhs_uns);
>>>>> + gimple_set_location (g, gimple_location (stmt));
>>>>> + gsi_replace (gsi, g, true);
>>>>> + return true;
>>>>> + }
>>>>> default:
>>>>> break;
>>>>> }
>>>>> @@ -19128,6 +19198,14 @@ builtin_function_type (machine_mode mode_ret, machine_mode mode_arg0,
>>>>> h.uns_p[2] = 1;
>>>>> break;
>>>>>
>>>>> + /* unsigned second arguments (vector shift right). */
>>>>> + case ALTIVEC_BUILTIN_VSRB:
>>>>> + case ALTIVEC_BUILTIN_VSRH:
>>>>> + case ALTIVEC_BUILTIN_VSRW:
>>>>> + case P8V_BUILTIN_VSRD:
>>>>> + h.uns_p[2] = 1;
>>>>> + break;
>>>>> +
>>>>> default:
>>>>> break;
>>>>> }
>>>>> diff --git a/gcc/testsuite/gcc.target/powerpc/fold-vec-shift-char.c b/gcc/testsuite/gcc.target/powerpc/fold-vec-shift-char.c
>>>>> new file mode 100644
>>>>> index 0000000..ebe91e7
>>>>> --- /dev/null
>>>>> +++ b/gcc/testsuite/gcc.target/powerpc/fold-vec-shift-char.c
>>>>> @@ -0,0 +1,66 @@
>>>>> +/* Verify that overloaded built-ins for vec_sl with char
>>>>> + inputs produce the right results. */
>>>>> +
>>>>> +/* { dg-do compile } */
>>>>> +/* { dg-require-effective-target powerpc_altivec_ok } */
>>>>> +/* { dg-options "-maltivec -O2" } */
>>>>> +
>>>>> +#include <altivec.h>
>>>>> +
>>>>> +//# vec_sl - shift left
>>>>> +//# vec_sr - shift right
>>>>> +//# vec_sra - shift right algebraic
>>>>> +//# vec_rl - rotate left
>>>>> +
>>>>> +vector signed char
>>>>> +testsl_signed (vector signed char x, vector unsigned char y)
>>>>> +{
>>>>> + return vec_sl (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned char
>>>>> +testsl_unsigned (vector unsigned char x, vector unsigned char y)
>>>>> +{
>>>>> + return vec_sl (x, y);
>>>>> +}
>>>>> +
>>>>> +vector signed char
>>>>> +testsr_signed (vector signed char x, vector unsigned char y)
>>>>> +{
>>>>> + return vec_sr (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned char
>>>>> +testsr_unsigned (vector unsigned char x, vector unsigned char y)
>>>>> +{
>>>>> + return vec_sr (x, y);
>>>>> +}
>>>>> +
>>>>> +vector signed char
>>>>> +testsra_signed (vector signed char x, vector unsigned char y)
>>>>> +{
>>>>> + return vec_sra (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned char
>>>>> +testsra_unsigned (vector unsigned char x, vector unsigned char y)
>>>>> +{
>>>>> + return vec_sra (x, y);
>>>>> +}
>>>>> +
>>>>> +vector signed char
>>>>> +testrl_signed (vector signed char x, vector unsigned char y)
>>>>> +{
>>>>> + return vec_rl (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned char
>>>>> +testrl_unsigned (vector unsigned char x, vector unsigned char y)
>>>>> +{
>>>>> + return vec_rl (x, y);
>>>>> +}
>>>>> +
>>>>> +/* { dg-final { scan-assembler-times "vslb" 2 } } */
>>>>> +/* { dg-final { scan-assembler-times "vsrb" 2 } } */
>>>>> +/* { dg-final { scan-assembler-times "vsrab" 2 } } */
>>>>> +/* { dg-final { scan-assembler-times "vrlb" 2 } } */
>>>>> diff --git a/gcc/testsuite/gcc.target/powerpc/fold-vec-shift-int.c b/gcc/testsuite/gcc.target/powerpc/fold-vec-shift-int.c
>>>>> new file mode 100644
>>>>> index 0000000..e9c5fe1
>>>>> --- /dev/null
>>>>> +++ b/gcc/testsuite/gcc.target/powerpc/fold-vec-shift-int.c
>>>>> @@ -0,0 +1,61 @@
>>>>> +/* Verify that overloaded built-ins for vec_sl with int
>>>>> + inputs produce the right results. */
>>>>> +
>>>>> +/* { dg-do compile } */
>>>>> +/* { dg-require-effective-target powerpc_altivec_ok } */
>>>>> +/* { dg-options "-maltivec -O2" } */
>>>>> +
>>>>> +#include <altivec.h>
>>>>> +
>>>>> +vector signed int
>>>>> +testsl_signed (vector signed int x, vector unsigned int y)
>>>>> +{
>>>>> + return vec_sl (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned int
>>>>> +testsl_unsigned (vector unsigned int x, vector unsigned int y)
>>>>> +{
>>>>> + return vec_sl (x, y);
>>>>> +}
>>>>> +
>>>>> +vector signed int
>>>>> +testsr_signed (vector signed int x, vector unsigned int y)
>>>>> +{
>>>>> + return vec_sr (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned int
>>>>> +testsr_unsigned (vector unsigned int x, vector unsigned int y)
>>>>> +{
>>>>> + return vec_sr (x, y);
>>>>> +}
>>>>> +
>>>>> +vector signed int
>>>>> +testsra_signed (vector signed int x, vector unsigned int y)
>>>>> +{
>>>>> + return vec_sra (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned int
>>>>> +testsra_unsigned (vector unsigned int x, vector unsigned int y)
>>>>> +{
>>>>> + return vec_sra (x, y);
>>>>> +}
>>>>> +
>>>>> +vector signed int
>>>>> +testrl_signed (vector signed int x, vector unsigned int y)
>>>>> +{
>>>>> + return vec_rl (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned int
>>>>> +testrl_unsigned (vector unsigned int x, vector unsigned int y)
>>>>> +{
>>>>> + return vec_rl (x, y);
>>>>> +}
>>>>> +
>>>>> +/* { dg-final { scan-assembler-times "vslw" 2 } } */
>>>>> +/* { dg-final { scan-assembler-times "vsrw" 2 } } */
>>>>> +/* { dg-final { scan-assembler-times "vsraw" 2 } } */
>>>>> +/* { dg-final { scan-assembler-times "vrlw" 2 } } */
>>>>> diff --git a/gcc/testsuite/gcc.target/powerpc/fold-vec-shift-longlong.c b/gcc/testsuite/gcc.target/powerpc/fold-vec-shift-longlong.c
>>>>> new file mode 100644
>>>>> index 0000000..97b82cf
>>>>> --- /dev/null
>>>>> +++ b/gcc/testsuite/gcc.target/powerpc/fold-vec-shift-longlong.c
>>>>> @@ -0,0 +1,63 @@
>>>>> +/* Verify that overloaded built-ins for vec_sl with long long
>>>>> + inputs produce the right results. */
>>>>> +
>>>>> +/* { dg-do compile } */
>>>>> +/* { dg-require-effective-target powerpc_p8vector_ok } */
>>>>> +/* { dg-options "-mpower8-vector -O2" } */
>>>>> +
>>>>> +#include <altivec.h>
>>>>> +
>>>>> +vector signed long long
>>>>> +testsl_signed (vector signed long long x, vector unsigned long long y)
>>>>> +{
>>>>> + return vec_sl (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned long long
>>>>> +testsl_unsigned (vector unsigned long long x, vector unsigned long long y)
>>>>> +{
>>>>> + return vec_sl (x, y);
>>>>> +}
>>>>> +
>>>>> +vector signed long long
>>>>> +testsr_signed (vector signed long long x, vector unsigned long long y)
>>>>> +{
>>>>> + return vec_sr (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned long long
>>>>> +testsr_unsigned (vector unsigned long long x, vector unsigned long long y)
>>>>> +{
>>>>> + return vec_sr (x, y);
>>>>> +}
>>>>> +
>>>>> +vector signed long long
>>>>> +testsra_signed (vector signed long long x, vector unsigned long long y)
>>>>> +{
>>>>> + return vec_sra (x, y);
>>>>> +}
>>>>> +
>>>>> +/* watch for PR 79544 here (vsrd / vsrad issue) */
>>>>> +vector unsigned long long
>>>>> +testsra_unsigned (vector unsigned long long x, vector unsigned long long y)
>>>>> +{
>>>>> + return vec_sra (x, y);
>>>>> +}
>>>>> +
>>>>> +vector signed long long
>>>>> +testrl_signed (vector signed long long x, vector unsigned long long y)
>>>>> +{
>>>>> + return vec_rl (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned long long
>>>>> +testrl_unsigned (vector unsigned long long x, vector unsigned long long y)
>>>>> +{
>>>>> + return vec_rl (x, y);
>>>>> +}
>>>>> +
>>>>> +/* { dg-final { scan-assembler-times "vsld" 2 } } */
>>>>> +/* { dg-final { scan-assembler-times "vsrd" 2 } } */
>>>>> +/* { dg-final { scan-assembler-times "vsrad" 2 } } */
>>>>> +/* { dg-final { scan-assembler-times "vrld" 2 } } */
>>>>> +
>>>>> diff --git a/gcc/testsuite/gcc.target/powerpc/fold-vec-shift-short.c b/gcc/testsuite/gcc.target/powerpc/fold-vec-shift-short.c
>>>>> new file mode 100644
>>>>> index 0000000..4ca7c18
>>>>> --- /dev/null
>>>>> +++ b/gcc/testsuite/gcc.target/powerpc/fold-vec-shift-short.c
>>>>> @@ -0,0 +1,61 @@
>>>>> +/* Verify that overloaded built-ins for vec_sl with short
>>>>> + inputs produce the right results. */
>>>>> +
>>>>> +/* { dg-do compile } */
>>>>> +/* { dg-require-effective-target powerpc_altivec_ok } */
>>>>> +/* { dg-options "-maltivec -O2" } */
>>>>> +
>>>>> +#include <altivec.h>
>>>>> +
>>>>> +vector signed short
>>>>> +testsl_signed (vector signed short x, vector unsigned short y)
>>>>> +{
>>>>> + return vec_sl (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned short
>>>>> +testsl_unsigned (vector unsigned short x, vector unsigned short y)
>>>>> +{
>>>>> + return vec_sl (x, y);
>>>>> +}
>>>>> +
>>>>> +vector signed short
>>>>> +testsr_signed (vector signed short x, vector unsigned short y)
>>>>> +{
>>>>> + return vec_sr (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned short
>>>>> +testsr_unsigned (vector unsigned short x, vector unsigned short y)
>>>>> +{
>>>>> + return vec_sr (x, y);
>>>>> +}
>>>>> +
>>>>> +vector signed short
>>>>> +testsra_signed (vector signed short x, vector unsigned short y)
>>>>> +{
>>>>> + return vec_sra (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned short
>>>>> +testsra_unsigned (vector unsigned short x, vector unsigned short y)
>>>>> +{
>>>>> + return vec_sra (x, y);
>>>>> +}
>>>>> +
>>>>> +vector signed short
>>>>> +testrl_signed (vector signed short x, vector unsigned short y)
>>>>> +{
>>>>> + return vec_rl (x, y);
>>>>> +}
>>>>> +
>>>>> +vector unsigned short
>>>>> +testrl_unsigned (vector unsigned short x, vector unsigned short y)
>>>>> +{
>>>>> + return vec_rl (x, y);
>>>>> +}
>>>>> +
>>>>> +/* { dg-final { scan-assembler-times "vslh" 2 } } */
>>>>> +/* { dg-final { scan-assembler-times "vsrh" 2 } } */
>>>>> +/* { dg-final { scan-assembler-times "vsrah" 2 } } */
>>>>> +/* { dg-final { scan-assembler-times "vrlh" 2 } } */
>