On Fri, Aug 6, 2021 at 7:27 PM Richard Biener via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> On Fri, Aug 6, 2021 at 11:05 AM Richard Sandiford
> <richard.sandif...@arm.com> wrote:
> >
> > Richard Biener via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
> > > On Fri, Aug 6, 2021 at 5:32 AM liuhongt <hongtao....@intel.com> wrote:
> > >>
> > >> Hi:
> > >> ---
> > >> OK, I think sth is amiss here upthread. insv/extv do look like they
> > >> are designed
> > >> to work on integer modes (but docs do not say anything about this here).
> > >> In fact the caller of extract_bit_field_using_extv is named
> > >> extract_integral_bit_field. Of course nothing seems to check what kind
> > >> of
> > >> modes we're dealing with, but we're for example happily doing
> > >> expand_shift in 'mode'. In the extract_integral_bit_field call 'mode' is
> > >> some integer mode and op0 is HFmode? From the above I get it's
> > >> the other way around? In that case we should wrap the
> > >> call to extract_integral_bit_field, extracting in an integer mode with
> > >> the
> > >> same size as 'mode' and then converting the result as (subreg:HF (reg:HI
> > >> ...)).
> > >> ---
> > >> This is a separate patch as a follow up of upper comments.
> > >>
> > >> gcc/ChangeLog:
> > >>
> > >> * expmed.c (extract_bit_field_1): Wrap the call to
> > >> extract_integral_bit_field, extracting in an integer mode with
> > >> the same size as 'tmode' and then converting the result
> > >> as (subreg:tmode (reg:imode)).
> > >>
> > >> gcc/testsuite/ChangeLog:
> > >> * gcc.target/i386/float16-5.c: New test.
> > >> ---
> > >> gcc/expmed.c | 19 +++++++++++++++++++
> > >> gcc/testsuite/gcc.target/i386/float16-5.c | 12 ++++++++++++
> > >> 2 files changed, 31 insertions(+)
> > >> create mode 100644 gcc/testsuite/gcc.target/i386/float16-5.c
> > >>
> > >> diff --git a/gcc/expmed.c b/gcc/expmed.c
> > >> index 3143f38e057..72790693ef0 100644
> > >> --- a/gcc/expmed.c
> > >> +++ b/gcc/expmed.c
> > >> @@ -1850,6 +1850,25 @@ extract_bit_field_1 (rtx str_rtx, poly_uint64
> > >> bitsize, poly_uint64 bitnum,
> > >> op0_mode = opt_scalar_int_mode ();
> > >> }
> > >>
> > >> + /* Make sure we are playing with integral modes. Pun with subregs
> > >> + if we aren't. When tmode is HFmode, op0 is SImode, there will be
> > >> ICE
> > >> + in extract_integral_bit_field. */
> > >> + if (int_mode_for_mode (tmode).exists (&imode)
> > >
> > > check !INTEGRAL_MODE_P (tmode) before, that should be slightly
> > > cheaper. Then imode should always be != tmode. Maybe
> > > even GET_MDOE_CLASS (tmode) != MODE_INT since I'm not sure
> > > how it behaves for composite modes.
> > >
> > > Of course the least surprises would happen when we restrict this
> > > to FLOAT_MODE_P (tmode).
> > >
> > > Richard - any preferences?
> >
> > If the bug is that extract_integral_bit_field is being called with
> > a non-integral mode parameter, then it looks odd that we can still
> > fall through to it without an integral mode (when exists is false).
> >
> > If calling extract_integral_bit_field without an integral mode is
> > a bug then I think we should have:
> >
> > int_mode_for_mode (mode).require ()
> >
> > whenever mode is not already SCALAR_INT_MODE_P/is_a<scalar_int_mode>.
> > Ideally we'd make the mode parameter scalar_int_mode too.
> >
> > extract_integral_bit_field currently has:
> >
> > /* Find a correspondingly-sized integer field, so we can apply
> > shifts and masks to it. */
> > scalar_int_mode int_mode;
> > if (!int_mode_for_mode (tmode).exists (&int_mode))
> > /* If this fails, we should probably push op0 out to memory and then
> > do a load. */
> > int_mode = int_mode_for_mode (mode).require ();
> >
> > which would seem to be redundant after this change.
>
> I'm not sure what exactly the bug is, but extract_integral_bit_field ends
> up creating a lowpart subreg that's not allowed and that ICEs (and I
> can't see a way to check beforehand). So it seems to me at least
> part of that function doesn't expect non-integral extraction modes.
>
> But who knows - the code is older than I am (OK, not, but older than
> my involvment in GCC ;))
>
How about attached patch w/ below changelog
gcc/ChangeLog:
* expmed.c (extract_bit_field_1): Make sure we're playing with
integral modes before call extract_integral_bit_field.
(extract_integral_bit_field): Add a parameter of type
scalar_int_mode which corresponds to of tmode.
And call extract_and_convert_fixed_bit_field instead of
extract_fixed_bit_field and convert_extracted_bit_field.
(extract_and_convert_fixed_bit_field): New function, it's a
combination of extract_fixed_bit_field and
convert_extracted_bit_field.
gcc/testsuite/ChangeLog:
* gcc.target/i386/float16-5.c: New test.
> Richard.
>
> > >> + && imode != tmode
> > >> + && imode != GET_MODE (op0))
> > >> + {
> > >> + rtx ret = extract_integral_bit_field (op0, op0_mode,
> > >> + bitsize.to_constant (),
> > >> + bitnum.to_constant (),
> > >> unsignedp,
> > >> + NULL, imode, imode,
> > >> + reverse, fallback_p);
> > >> + gcc_assert (ret);
> > >> +
> > >> + if (!REG_P (ret))
> > >> + ret = force_reg (imode, ret);
> > >> + return gen_lowpart_SUBREG (tmode, ret);
> > >> + }
> > >> +
> > >> /* It's possible we'll need to handle other cases here for
> > >> polynomial bitnum and bitsize. */
> >
> > Minor nit, but since the code is using to_constant, it should go after
> > this comment rather than before it.
> >
> > Thanks,
> > Richard
> >
> > >>
> > >> diff --git a/gcc/testsuite/gcc.target/i386/float16-5.c
> > >> b/gcc/testsuite/gcc.target/i386/float16-5.c
> > >> new file mode 100644
> > >> index 00000000000..ebc0af1490b
> > >> --- /dev/null
> > >> +++ b/gcc/testsuite/gcc.target/i386/float16-5.c
> > >> @@ -0,0 +1,12 @@
> > >> +/* { dg-do compile } */
> > >> +/* { dg-options "-msse2 -O2" } */
> > >> +_Float16
> > >> +foo (int a)
> > >> +{
> > >> + union {
> > >> + int a;
> > >> + _Float16 b;
> > >> + }c;
> > >> + c.a = a;
> > >> + return c.b;
> > >> +}
> > >> --
> > >> 2.27.0
> > >>
--
BR,
Hongtao
From 9c77ac15e69b567156a82debe45e3ced10df1110 Mon Sep 17 00:00:00 2001
From: liuhongt <hongtao....@intel.com>
Date: Fri, 6 Aug 2021 10:18:43 +0800
Subject: [PATCH] Make sure we're playing with integral modes before call
extract_integral_bit_field.
gcc/ChangeLog:
* expmed.c (extract_bit_field_1): Make sure we're playing with
integral modes before call extract_integral_bit_field.
(extract_integral_bit_field): Add a parameter of type
scalar_int_mode which corresponds to of tmode.
And call extract_and_convert_fixed_bit_field instead of
extract_fixed_bit_field and convert_extracted_bit_field.
(extract_and_convert_fixed_bit_field): New function, it's a
combination of extract_fixed_bit_field and
convert_extracted_bit_field.
gcc/testsuite/ChangeLog:
* gcc.target/i386/float16-5.c: New test.
---
gcc/expmed.c | 103 ++++++++++++++++------
gcc/testsuite/gcc.target/i386/float16-5.c | 12 +++
2 files changed, 90 insertions(+), 25 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/i386/float16-5.c
diff --git a/gcc/expmed.c b/gcc/expmed.c
index 3143f38e057..f083d6e86d0 100644
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -71,7 +71,14 @@ static void store_split_bit_field (rtx, opt_scalar_int_mode,
static rtx extract_integral_bit_field (rtx, opt_scalar_int_mode,
unsigned HOST_WIDE_INT,
unsigned HOST_WIDE_INT, int, rtx,
- machine_mode, machine_mode, bool, bool);
+ machine_mode, machine_mode,
+ scalar_int_mode, bool, bool);
+static rtx extract_and_convert_fixed_bit_field (scalar_int_mode,
+ machine_mode, machine_mode,
+ rtx, opt_scalar_int_mode,
+ unsigned HOST_WIDE_INT,
+ unsigned HOST_WIDE_INT, rtx,
+ int, bool);
static rtx extract_fixed_bit_field (machine_mode, rtx, opt_scalar_int_mode,
unsigned HOST_WIDE_INT,
unsigned HOST_WIDE_INT, rtx, int, bool);
@@ -1632,6 +1639,7 @@ extract_bit_field_1 (rtx str_rtx, poly_uint64 bitsize, poly_uint64 bitnum,
{
rtx op0 = str_rtx;
machine_mode mode1;
+ scalar_int_mode int_tmode;
if (tmode == VOIDmode)
tmode = mode;
@@ -1853,10 +1861,46 @@ extract_bit_field_1 (rtx str_rtx, poly_uint64 bitsize, poly_uint64 bitnum,
/* It's possible we'll need to handle other cases here for
polynomial bitnum and bitsize. */
+ /* Make sure we are playing with integral modes. Pun with subregs
+ if we aren't. When tmode is HFmode, op0 is SImode, there will be ICE
+ in extract_integral_bit_field. */
+ opt_scalar_int_mode target_imode = int_mode_for_mode (tmode);
+ if (!target_imode.exists (&int_tmode) || int_tmode != tmode)
+ {
+ if (target_imode.exists (&int_tmode))
+ {
+ rtx ret = extract_integral_bit_field (op0, op0_mode,
+ bitsize.to_constant (),
+ bitnum.to_constant (),
+ unsignedp, NULL, int_tmode,
+ int_tmode, int_tmode,
+ reverse, fallback_p);
+ gcc_assert (ret);
+
+ if (!REG_P (ret))
+ ret = force_reg (int_tmode, ret);
+ return gen_lowpart_SUBREG (tmode, ret);
+ }
+ else
+ {
+ if (!fallback_p)
+ return NULL;
+
+ int_tmode = int_mode_for_mode (mode).require ();
+ return extract_and_convert_fixed_bit_field (int_tmode, tmode, mode,
+ op0, op0_mode,
+ bitsize.to_constant (),
+ bitnum.to_constant (),
+ target, unsignedp,
+ reverse);
+ }
+ }
+
/* From here on we need to be looking at a fixed-size insertion. */
return extract_integral_bit_field (op0, op0_mode, bitsize.to_constant (),
bitnum.to_constant (), unsignedp,
- target, mode, tmode, reverse, fallback_p);
+ target, mode, tmode,
+ int_tmode, reverse, fallback_p);
}
/* Subroutine of extract_bit_field_1, with the same arguments, except
@@ -1869,6 +1913,7 @@ extract_integral_bit_field (rtx op0, opt_scalar_int_mode op0_mode,
unsigned HOST_WIDE_INT bitsize,
unsigned HOST_WIDE_INT bitnum, int unsignedp,
rtx target, machine_mode mode, machine_mode tmode,
+ scalar_int_mode int_tmode,
bool reverse, bool fallback_p)
{
/* Handle fields bigger than a word. */
@@ -2035,29 +2080,10 @@ extract_integral_bit_field (rtx op0, opt_scalar_int_mode op0_mode,
if (!fallback_p)
return NULL;
- /* Find a correspondingly-sized integer field, so we can apply
- shifts and masks to it. */
- scalar_int_mode int_mode;
- if (!int_mode_for_mode (tmode).exists (&int_mode))
- /* If this fails, we should probably push op0 out to memory and then
- do a load. */
- int_mode = int_mode_for_mode (mode).require ();
-
- target = extract_fixed_bit_field (int_mode, op0, op0_mode, bitsize,
- bitnum, target, unsignedp, reverse);
-
- /* Complex values must be reversed piecewise, so we need to undo the global
- reversal, convert to the complex mode and reverse again. */
- if (reverse && COMPLEX_MODE_P (tmode))
- {
- target = flip_storage_order (int_mode, target);
- target = convert_extracted_bit_field (target, mode, tmode, unsignedp);
- target = flip_storage_order (tmode, target);
- }
- else
- target = convert_extracted_bit_field (target, mode, tmode, unsignedp);
-
- return target;
+ return extract_and_convert_fixed_bit_field (int_tmode, tmode, mode,
+ op0, op0_mode, bitsize,
+ bitnum, target, unsignedp,
+ reverse);
}
/* Generate code to extract a byte-field from STR_RTX
@@ -2129,6 +2155,33 @@ extract_bit_field (rtx str_rtx, poly_uint64 bitsize, poly_uint64 bitnum,
return extract_bit_field_1 (str_rtx, bitsize, bitnum, unsignedp,
target, mode, tmode, reverse, true, alt_rtl);
}
+
+/* Combination of extract_fixed_bit_field and convert_extracted_bit_field. */
+static rtx
+extract_and_convert_fixed_bit_field (scalar_int_mode int_tmode,
+ machine_mode tmode, machine_mode mode,
+ rtx op0, opt_scalar_int_mode op0_mode,
+ unsigned HOST_WIDE_INT bitsize,
+ unsigned HOST_WIDE_INT bitnum,
+ rtx target, int unsignedp, bool reverse)
+{
+ target = extract_fixed_bit_field (int_tmode, op0, op0_mode, bitsize,
+ bitnum, target, unsignedp, reverse);
+
+ /* Complex values must be reversed piecewise, so we need to undo the global
+ reversal, convert to the complex mode and reverse again. */
+ if (reverse && COMPLEX_MODE_P (tmode))
+ {
+ target = flip_storage_order (int_tmode, target);
+ target = convert_extracted_bit_field (target, mode, tmode, unsignedp);
+ target = flip_storage_order (tmode, target);
+ }
+ else
+ target = convert_extracted_bit_field (target, mode, tmode, unsignedp);
+
+ return target;
+}
+
/* Use shifts and boolean operations to extract a field of BITSIZE bits
from bit BITNUM of OP0. If OP0_MODE is defined, it is the mode of OP0,
diff --git a/gcc/testsuite/gcc.target/i386/float16-5.c b/gcc/testsuite/gcc.target/i386/float16-5.c
new file mode 100644
index 00000000000..ebc0af1490b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/float16-5.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-msse2 -O2" } */
+_Float16
+foo (int a)
+{
+ union {
+ int a;
+ _Float16 b;
+ }c;
+ c.a = a;
+ return c.b;
+}
--
2.27.0
