From 5c553ae52601171a96122207a3c57abd4e6545cb Mon Sep 17 00:00:00 2001
From: ian <ian@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Mon, 5 Feb 2018 19:26:29 +0000
Subject: [PATCH]     compiler: rollback "avoid negative zero in float
 constants"

    It uses functions that are not available in MPFR 2.4.2, which is the
    current version supported by GCC.

    Original change description:

        compiler: avoid negative zero in float constants

        Check for negative numbers with very small magnitudes that will round
        to negative zero, and force them to positive zero instead.

        This implements the spec clarification in https://golang.org/cl/14727.
        The test is in https://golang.org/cl/91895.

        Fixes golang/go#12621

    Updates golang/go#12621

    Reviewed-on: https://go-review.googlesource.com/92055


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@257393 138bc75d-0d04-0410-961f-82ee72b054a4
---
 gcc/go/gofrontend/MERGE          |  2 +-
 gcc/go/gofrontend/expressions.cc | 52 ++--------------------------------------
 gcc/go/gofrontend/expressions.h  |  3 ---
 3 files changed, 3 insertions(+), 54 deletions(-)

diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index 545b40f42e4..ba8a8e0b48b 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-7eebd495df915ab87926b8dd88f554674cfdacea
+c02c71187c9794b50444e2858c582e66a3442ee8
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
diff --git a/gcc/go/gofrontend/expressions.cc b/gcc/go/gofrontend/expressions.cc
index 03f8c68cace..8555c052980 100644
--- a/gcc/go/gofrontend/expressions.cc
+++ b/gcc/go/gofrontend/expressions.cc
@@ -16158,16 +16158,10 @@ Numeric_constant::set_float(Type* type, const mpfr_t val)
   this->clear();
   this->classification_ = NC_FLOAT;
   this->type_ = type;
-
   // Numeric constants do not have negative zero values, so remove
   // them here.  They also don't have infinity or NaN values, but we
   // should never see them here.
-  int bits = 0;
-  if (type != NULL
-      && type->float_type() != NULL
-      && !type->float_type()->is_abstract())
-    bits = type->float_type()->bits();
-  if (Numeric_constant::is_float_zero(val, bits))
+  if (mpfr_zero_p(val))
     mpfr_init_set_ui(this->u_.float_val, 0, GMP_RNDN);
   else
     mpfr_init_set(this->u_.float_val, val, GMP_RNDN);
@@ -16181,50 +16175,8 @@ Numeric_constant::set_complex(Type* type, const mpc_t val)
   this->clear();
   this->classification_ = NC_COMPLEX;
   this->type_ = type;
-
-  // Avoid negative zero as in set_float.
-  int bits = 0;
-  if (type != NULL
-      && type->complex_type() != NULL
-      && !type->complex_type()->is_abstract())
-    bits = type->complex_type()->bits() / 2;
-
-  mpfr_t real;
-  mpfr_init_set(real, mpc_realref(val), GMP_RNDN);
-  if (Numeric_constant::is_float_zero(real, bits))
-    mpfr_set_ui(real, 0, GMP_RNDN);
-
-  mpfr_t imag;
-  mpfr_init_set(imag, mpc_imagref(val), GMP_RNDN);
-  if (Numeric_constant::is_float_zero(imag, bits))
-    mpfr_set_ui(imag, 0, GMP_RNDN);
-
   mpc_init2(this->u_.complex_val, mpc_precision);
-  mpc_set_fr_fr(this->u_.complex_val, real, imag, MPC_RNDNN);
-
-  mpfr_clear(real);
-  mpfr_clear(imag);
-}
-
-// Return whether VAL, at a precision of BITS, is zero.  BITS may be
-// zero in which case it is ignored.
-
-bool
-Numeric_constant::is_float_zero(const mpfr_t val, int bits)
-{
-  if (mpfr_zero_p(val))
-    return true;
-  switch (bits)
-    {
-    case 0:
-      return false;
-    case 32:
-      return mpfr_get_flt(val, GMP_RNDN) == 0;
-    case 64:
-      return mpfr_get_d(val, GMP_RNDN) == 0;
-    default:
-      go_unreachable();
-    }
+  mpc_set(this->u_.complex_val, val, MPC_RNDNN);
 }
 
 // Get an int value.
diff --git a/gcc/go/gofrontend/expressions.h b/gcc/go/gofrontend/expressions.h
index 3acaeb2b022..d16a284b6b0 100644
--- a/gcc/go/gofrontend/expressions.h
+++ b/gcc/go/gofrontend/expressions.h
@@ -4220,9 +4220,6 @@ class Numeric_constant
   bool
   check_complex_type(Complex_type*, bool, Location);
 
-  static bool
-  is_float_zero(const mpfr_t, int bits);
-
   // The kinds of constants.
   enum Classification
   {
-- 
2.11.4.GIT