src: Apply upstream commit:

[maya <maya%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/007a1527debf
branches:  trunk
changeset: 318287:007a1527debf
user:      maya <maya%NetBSD.org@localhost>
date:      Tue Apr 17 10:02:49 2018 +0000
description:
Apply upstream commit:

From: ppalka <ppalka@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Wed, 27 Apr 2016 21:18:05 +0000
Subject: [PATCH] Reduce nesting of parentheses in conditionals generated by
 genattrtab

gcc/ChangeLog:

        * genattrtab.c (write_test_expr): New parameter EMIT_PARENS
        which defaults to true.  Emit an outer pair of parentheses only if
        EMIT_PARENS.  When continuing a chain of && or || (or & or |),
        don't emit parentheses for the right-hand operand.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@235536

gcc/arm generates so many parens it hits a bracket depth limited which is
enforced by clang. This reduces the number of parens generated and avoids the
need to increase bracket depth.

Fixes PR toolchain/53178 properly.

diffstat:

 external/gpl3/gcc/dist/gcc/genattrtab.c |  33 ++++++++++++++++++++++++---------
 1 files changed, 24 insertions(+), 9 deletions(-)

diffs (69 lines):

diff -r 359fa12d8367 -r 007a1527debf external/gpl3/gcc/dist/gcc/genattrtab.c
--- a/external/gpl3/gcc/dist/gcc/genattrtab.c   Tue Apr 17 09:06:33 2018 +0000
+++ b/external/gpl3/gcc/dist/gcc/genattrtab.c   Tue Apr 17 10:02:49 2018 +0000
@@ -3416,7 +3416,10 @@
 
 /* Given a piece of RTX, print a C expression to test its truth value to OUTF.
    We use AND and IOR both for logical and bit-wise operations, so
-   interpret them as logical unless they are inside a comparison expression.  */
+   interpret them as logical unless they are inside a comparison expression.
+
+   An outermost pair of parentheses is emitted around this C expression unless
+   EMIT_PARENS is false.  */
 
 /* Interpret AND/IOR as bit-wise operations instead of logical.  */
 #define FLG_BITWISE            1
@@ -3432,16 +3435,16 @@
 #define FLG_OUTSIDE_AND                8
 
 static unsigned int
-write_test_expr (FILE *outf, rtx exp, unsigned int attrs_cached, int flags)
+write_test_expr (FILE *outf, rtx exp, unsigned int attrs_cached, int flags,
+                bool emit_parens = true)
 {
   int comparison_operator = 0;
   RTX_CODE code;
   struct attr_desc *attr;
 
-  /* In order not to worry about operator precedence, surround our part of
-     the expression with parentheses.  */
-
-  fprintf (outf, "(");
+  if (emit_parens)
+    fprintf (outf, "(");
+
   code = GET_CODE (exp);
   switch (code)
     {
@@ -3575,8 +3578,18 @@
              || GET_CODE (XEXP (exp, 1)) == EQ_ATTR
              || (GET_CODE (XEXP (exp, 1)) == NOT
                  && GET_CODE (XEXP (XEXP (exp, 1), 0)) == EQ_ATTR)))
-       attrs_cached
-         = write_test_expr (outf, XEXP (exp, 1), attrs_cached, flags);
+       {
+         bool need_parens = true;
+
+         /* No need to emit parentheses around the right-hand operand if we are
+            continuing a chain of && or || (or & or |).  */
+         if (GET_CODE (XEXP (exp, 1)) == code)
+           need_parens = false;
+
+         attrs_cached
+           = write_test_expr (outf, XEXP (exp, 1), attrs_cached, flags,
+                              need_parens);
+       }
       else
        write_test_expr (outf, XEXP (exp, 1), attrs_cached,
                         flags | comparison_operator);
@@ -3794,7 +3807,9 @@
             GET_RTX_NAME (code));
     }
 
-  fprintf (outf, ")");
+  if (emit_parens)
+    fprintf (outf, ")");
+
   return attrs_cached;
 }