On Tue, Jul 2, 2024 at 10:11 AM Richard Biener
<richard.guent...@gmail.com> wrote:
>
> On Mon, Jul 1, 2024 at 11:48 PM Andrew Pinski <quic_apin...@quicinc.com>
> wrote:
> >
> > While looking into the original folding code for cabs
> > (moved to match in r6-4111-gabcc43f5323869), I noticed that
> > `cabs(x+0i)` was optimized even without the need of sqrt.
> > I also noticed that now the code generation in this case
> > will be worse if the target had a sqrt. So let's implement
> > this small optimizations in gimple_expand_builtin_cabs.
> > Note `cabs(x+0i)` is done without unsafe math optimizations.
> > This is because the definition of `cabs(x+0i)` is `hypot(x, 0)`
> > and the definition in the standard says that just returns `abs(x)`.
> >
> > Bootstrapped and tested on x86_64-linux-gnu with no regressions.
>
> OK.
>
> Btw, I was wondering if there's any concern about errno given
> hypot documents some but cabs doesn't (and sqrt doesn't set
> any)?
Likewise sNaNs might fail to get to qNaNs with cabs(sNaN + 0i)
to abs (sNaN)?
> > gcc/ChangeLog:
> >
> > * tree-complex.cc (gimple_expand_builtin_cabs): Add
> > `cabs(a+ai)`, `cabs(x+0i)` and `cabs(0+xi)` optimizations.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * gcc.dg/tree-ssa/cabs-3.c: New test.
> > * gcc.dg/tree-ssa/cabs-4.c: New test.
> > * gcc.dg/tree-ssa/cabs-5.c: New test.
> > * gcc.dg/tree-ssa/cabs-6.c: New test.
> >
> > Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> >
> > Fix optimizations
> >
> > Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> > ---
> > gcc/testsuite/gcc.dg/tree-ssa/cabs-3.c | 24 +++++++++++
> > gcc/testsuite/gcc.dg/tree-ssa/cabs-4.c | 16 ++++++++
> > gcc/testsuite/gcc.dg/tree-ssa/cabs-5.c | 22 ++++++++++
> > gcc/testsuite/gcc.dg/tree-ssa/cabs-6.c | 16 ++++++++
> > gcc/tree-complex.cc | 56 +++++++++++++++++++++-----
> > 5 files changed, 123 insertions(+), 11 deletions(-)
> > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/cabs-3.c
> > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/cabs-4.c
> > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/cabs-5.c
> > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/cabs-6.c
> >
> > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/cabs-3.c
> > b/gcc/testsuite/gcc.dg/tree-ssa/cabs-3.c
> > new file mode 100644
> > index 00000000000..976c0169131
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/tree-ssa/cabs-3.c
> > @@ -0,0 +1,24 @@
> > +/* { dg-do compile { target sqrt_insn } } */
> > +/* { dg-options "-Ofast -fdump-tree-cplxlower1" } */
> > +/* { dg-add-options sqrt_insn } */
> > +
> > +
> > +double f(double a, double c)
> > +{
> > + _Complex double b = a;
> > + b+= c;
> > + return __builtin_cabs(b);
> > +}
> > +
> > +double f1(double a, double c)
> > +{
> > + _Complex double b = __builtin_complex(0.0, a);
> > + b+= __builtin_complex(0.0, c);
> > + return __builtin_cabs(b);
> > +}
> > +
> > +/* Check that cabs is expanded during complex lowering. */
> > +/* { dg-final { scan-tree-dump-not "__builtin_cabs " "cplxlower1" } } */
> > +/* { dg-final { scan-tree-dump-not "__builtin_sqrt " "cplxlower1" } } */
> > +/* { dg-final { scan-tree-dump-times "ABS_EXPR <" 2 "cplxlower1" } } */
> > +
> > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/cabs-4.c
> > b/gcc/testsuite/gcc.dg/tree-ssa/cabs-4.c
> > new file mode 100644
> > index 00000000000..00aa3c9d4e7
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/tree-ssa/cabs-4.c
> > @@ -0,0 +1,16 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-Ofast -fdump-tree-cplxlower1" } */
> > +
> > +double f(double a, double c)
> > +{
> > + _Complex double d = __builtin_complex (a, a);
> > + d+=__builtin_complex(1.0, 1.0);
> > + return __builtin_cabs(d);
> > +}
> > +
> > +/* Check that cabs is expanded during complex lowering and there is no
> > sqrt (since it is a constant). */
> > +/* { dg-final { scan-tree-dump-not "__builtin_cabs " "cplxlower1" } } */
> > +/* { dg-final { scan-tree-dump-not "__builtin_sqrt " "cplxlower1" } } */
> > +/* { dg-final { scan-tree-dump-times "ABS_EXPR <" 1 "cplxlower1" } } */
> > +
> > +
> > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/cabs-5.c
> > b/gcc/testsuite/gcc.dg/tree-ssa/cabs-5.c
> > new file mode 100644
> > index 00000000000..dd794079921
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/tree-ssa/cabs-5.c
> > @@ -0,0 +1,22 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O2 -fdump-tree-cplxlower1" } */
> > +
> > +double f(double a, double c)
> > +{
> > + _Complex double b = a;
> > + b+= c;
> > + return __builtin_cabs(b);
> > +}
> > +
> > +double f1(double a, double c)
> > +{
> > + _Complex double b = __builtin_complex(0.0, a);
> > + b+= __builtin_complex(0.0, c);
> > + return __builtin_cabs(b);
> > +}
> > +
> > +/* Check that cabs is expanded into ABS for both f and f1 during complex
> > lowering. */
> > +/* { dg-final { scan-tree-dump-not "__builtin_cabs " "cplxlower1" } } */
> > +/* { dg-final { scan-tree-dump-not "__builtin_sqrt " "cplxlower1" } } */
> > +/* { dg-final { scan-tree-dump-times "ABS_EXPR <" 2 "cplxlower1" } } */
> > +
> > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/cabs-6.c
> > b/gcc/testsuite/gcc.dg/tree-ssa/cabs-6.c
> > new file mode 100644
> > index 00000000000..bc88932449c
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/tree-ssa/cabs-6.c
> > @@ -0,0 +1,16 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-Ofast -fdump-tree-cplxlower1" } */
> > +
> > +double f(double a, double c)
> > +{
> > + _Complex double d = __builtin_complex (a, 0.0);
> > + d+=__builtin_complex(0.0, a);
> > + return __builtin_cabs(d);
> > +}
> > +
> > +/* Check that cabs is expanded during complex lowering and there is no
> > sqrt (since it is a constant). */
> > +/* { dg-final { scan-tree-dump-not "__builtin_cabs " "cplxlower1" } } */
> > +/* { dg-final { scan-tree-dump-not "__builtin_sqrt " "cplxlower1" } } */
> > +/* { dg-final { scan-tree-dump-times "ABS_EXPR <" 1 "cplxlower1" } } */
> > +
> > +
> > diff --git a/gcc/tree-complex.cc b/gcc/tree-complex.cc
> > index d1276dc1c2f..d2d9d76827d 100644
> > --- a/gcc/tree-complex.cc
> > +++ b/gcc/tree-complex.cc
> > @@ -1701,10 +1701,10 @@ expand_complex_asm (gimple_stmt_iterator *gsi)
> > }
> >
> >
> > -/* ARG is the argument to a cabs builtin call in GSI with location info
> > - LOC. Create a sequence of statements prior to GSI that calculates
> > - sqrt(R*R + I*I), where R and I are the real and imaginary components
> > - of ARG, respectively. */
> > +/* ARG is the argument to a cabs builtin call in GSI from the
> > + original OLD_STMT. Create a sequence of statements prior
> > + to GSI that calculates sqrt(R*R + I*I), where R and
> > + I are the real and imaginary components of ARG, respectively. */
> >
> > static void
> > gimple_expand_builtin_cabs (gimple_stmt_iterator *gsi, gimple *old_stmt)
> > @@ -1712,21 +1712,56 @@ gimple_expand_builtin_cabs (gimple_stmt_iterator
> > *gsi, gimple *old_stmt)
> > tree real_part, imag_part, addend1, addend2, sum;
> > tree arg = gimple_call_arg (old_stmt, 0);
> > tree type = TREE_TYPE (TREE_TYPE (arg));
> > - tree sqrtfn = mathfn_built_in (type, BUILT_IN_SQRT);
> > machine_mode mode = TYPE_MODE (type);
> > gimple *new_stmt;
> >
> > - if (!flag_unsafe_math_optimizations
> > - || !optimize_bb_for_speed_p (gimple_bb (old_stmt))
> > - || !sqrtfn
> > - || optab_handler (sqrt_optab, mode) == CODE_FOR_nothing)
> > - return;
> > + tree lhs = gimple_call_lhs (old_stmt);
> >
> > real_part = extract_component (gsi, arg, false, true);
> > imag_part = extract_component (gsi, arg, true, true);
> > location_t loc = gimple_location (old_stmt);
> >
> > gimple_seq stmts = NULL;
> > +
> > + /* cabs(x+0i) -> abs(x).
> > + cabs(0+xi) -> abs(x).
> > + These 2 can be done even without unsafe math optimizations. */
> > + if (real_zerop (imag_part)
> > + || real_zerop (real_part))
> > + {
> > + tree other = real_zerop (imag_part) ? real_part : imag_part;
> > + sum = gimple_build (&stmts, loc, ABS_EXPR, type, other);
> > + gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
> > + new_stmt = gimple_build_assign (lhs, sum);
> > + gimple_set_location (new_stmt, loc);
> > + gsi_replace (gsi, new_stmt, true);
> > + return;
> > + }
> > +
> > + if (!flag_unsafe_math_optimizations)
> > + return;
> > +
> > + /* cabs(x+xi) -> fabs(x)*sqrt(2). */
> > + if (operand_equal_p (real_part, imag_part))
> > + {
> > + tree sqrt2 = build_real_truncate (type, dconst_sqrt2 ());
> > + sum = gimple_build (&stmts, loc, ABS_EXPR, type, real_part);
> > + sum = gimple_build (&stmts, loc, MULT_EXPR, type, sum, sqrt2);
> > + gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
> > + new_stmt = gimple_build_assign (lhs, sum);
> > + gimple_set_location (new_stmt, loc);
> > + gsi_replace (gsi, new_stmt, true);
> > + return;
> > + }
> > +
> > + /* cabs(a+bi) -> sqrt(a*a+b*b) if sqrt exists on the target
> > + and optimizing for speed. */
> > + tree sqrtfn = mathfn_built_in (type, BUILT_IN_SQRT);
> > + if (!optimize_bb_for_speed_p (gimple_bb (old_stmt))
> > + || !sqrtfn
> > + || optab_handler (sqrt_optab, mode) == CODE_FOR_nothing)
> > + return;
> > +
> > addend1 = gimple_build (&stmts, loc, MULT_EXPR, type, real_part,
> > real_part);
> > addend2 = gimple_build (&stmts, loc, MULT_EXPR, type, imag_part,
> > imag_part);
> > sum = gimple_build (&stmts, loc, PLUS_EXPR, type, addend1, addend2);
> > @@ -1735,7 +1770,6 @@ gimple_expand_builtin_cabs (gimple_stmt_iterator
> > *gsi, gimple *old_stmt)
> > /* Build the sqrt call. */
> > new_stmt = gimple_build_call (sqrtfn, 1, sum);
> > gimple_set_location (new_stmt, loc);
> > - tree lhs = gimple_call_lhs (old_stmt);
> > gimple_call_set_lhs (new_stmt, lhs);
> > gsi_replace (gsi, new_stmt, true);
> > }
> > --
> > 2.43.0
> >
