Re: libgo patch committed: Update to go1.15rc1

[Ian Lance Taylor <iant@golang.org>]

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On Sun, Aug 2, 2020 at 1:00 PM Rainer Orth <ro@cebitec.uni-bielefeld.de> wrote:
>
> Hi Ian,
>
> > This libgo patch updates the sources to the go1.15rc1 release
> > candidate.  As usual, the changes for this update are too large to
> > include in an e-mail message.  I've just included the highlights and
> > changes to GCC-specific files below.  Bootstrapped and ran Go
> > testsuite on x86_64-pc-linux-gnu.  Committed to mainline.
>
> this seems to have broken the libgo build with 32-bit compilers:
>
> $ files=`echo /vol/gcc/src/hg/master/local/libgo/go/time/tzdata/tzdata.go /vol/gcc/src/hg/master/local/libgo/go/time/tzdata/zipdata.go errors.gox syscall.gox | sed -e 's/[^ ]*\.gox//g' -e 's/[^ ]*\.dep//'`; /bin/ksh ./libtool --tag GO --mode=compile /var/gcc/regression/master/11.4-gcc-gas/build/./gcc/gccgo -B/var/gcc/regression/master/11.4-gcc-gas/build/./gcc/ -B/vol/gcc/i386-pc-solaris2.11/bin/ -B/vol/gcc/i386-pc-solaris2.11/lib/ -isystem /vol/gcc/i386-pc-solaris2.11/include -isystem /vol/gcc/i386-pc-solaris2.11/sys-include   -fchecking=1  -minline-all-stringops  -O2 -g -I . -c -fgo-pkgpath=`echo time/tzdata.lo | sed -e 's/.lo$//'`  -o time/tzdata.lo $files
> libtool: compile:  /var/gcc/regression/master/11.4-gcc-gas/build/./gcc/gccgo -B/var/gcc/regression/master/11.4-gcc-gas/build/./gcc/ -B/vol/gcc/i386-pc-solaris2.11/bin/ -B/vol/gcc/i386-pc-solaris2.11/lib/ -isystem /vol/gcc/i386-pc-solaris2.11/include -isystem /vol/gcc/i386-pc-solaris2.11/sys-include -fchecking=1 -minline-all-stringops -O2 -g -I . -c -fgo-pkgpath=time/tzdata /vol/gcc/src/hg/master/local/libgo/go/time/tzdata/tzdata.go /vol/gcc/src/hg/master/local/libgo/go/time/tzdata/zipdata.go  -fPIC -o time/.libs/tzdata.o
> terminate called after throwing an instance of 'std::bad_alloc'
>   what():  std::bad_alloc
> go1: internal compiler error: Abort
> mmap: Not enough space
>
> I'm seeing this on all of i386-pc-solaris2.11, sparc-sun-solaris2.11,
> and i686-pc-linux-gnu.  amd64-pc-solaris2.11 and sparcv9-sun-solaris2.11
> are ok, though (running make check right now).

This is fixed by this patch to the Go frontend that deletes lowered
constant strings.  If we lower a constant string operation in a
Binary_expression, we delete the strings.  This is safe because
constant strings are always newly allocated.

This is a hack to use much less memory when compiling the new
time/tzdata package, which has a file that contains the sum of over
13,000 constant strings.  We don't do this for numeric expressions
because that could cause us to delete an Iota_expression.

The Go frontend should have a cleaner approach to memory usage some day.

This also fixes PR go/96450.  Bootstrapped and tested on
x86_64-pc-linux-gnu and verified that I could build the time/tzdata
package on i686-pc-linux-gnu.  Committed to mainline.

Ian

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2066393280f5c1573535c6a863c38cfe6baedae8
diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index 0bc8e1b5a59..c21b6000229 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-7f0d3834ac40cf3bcbeb9b13926ab5ccb2523537
+f45afedf90ac9af8f03d7d4515e952cbd724953a
 
 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 90f860bd735..7e7fb8c7313 100644
--- a/gcc/go/gofrontend/expressions.cc
+++ b/gcc/go/gofrontend/expressions.cc
@@ -556,7 +556,10 @@ Expression::get_backend(Translate_context* context)
 {
   // The child may have marked this expression as having an error.
   if (this->classification_ == EXPRESSION_ERROR)
-    return context->backend()->error_expression();
+    {
+      go_assert(saw_errors());
+      return context->backend()->error_expression();
+    }
 
   return this->do_get_backend(context);
 }
@@ -6080,6 +6083,8 @@ Binary_expression::do_lower(Gogo* gogo, Named_object*,
               Type* result_type = (left->type()->named_type() != NULL
                                    ? left->type()
                                    : right->type());
+	      delete left;
+	      delete right;
               return Expression::make_string_typed(left_string + right_string,
                                                    result_type, location);
             }
@@ -6087,6 +6092,8 @@ Binary_expression::do_lower(Gogo* gogo, Named_object*,
 	    {
 	      int cmp = left_string.compare(right_string);
 	      bool r = Binary_expression::cmp_to_bool(op, cmp);
+	      delete left;
+	      delete right;
 	      return Expression::make_boolean(r, location);
 	    }
 	}