[binutils-gdb] Constant fold view increment expressions

[Alan Modra]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=fb0e49d8e05e61ca2af9b5f60b01ad5fb6d274ff

commit fb0e49d8e05e61ca2af9b5f60b01ad5fb6d274ff
Author: Alan Modra <amodra@gmail.com>
Date:   Tue Mar 8 22:48:51 2022 +1030

    Constant fold view increment expressions
    
    The idea here is to replace expressions like v + 1 + 1 + 1 with v + 3.
    
            * dwarf2dbg.c (set_or_check_view): Remove useless assertion.
            Resolve multiple view increments.
            * testsuite/gas/elf/dwarf2-18.d: Don't xfail mep.

Diff:
---
 gas/dwarf2dbg.c                   | 17 +++++++++++++----
 gas/testsuite/gas/elf/dwarf2-18.d |  3 +--
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/gas/dwarf2dbg.c b/gas/dwarf2dbg.c
index 7269c4cdf87..ba97b5f0126 100644
--- a/gas/dwarf2dbg.c
+++ b/gas/dwarf2dbg.c
@@ -402,18 +402,27 @@ set_or_check_view (struct line_entry *e, struct line_entry *p,
   if (viewx.X_op != O_constant || viewx.X_add_number)
     {
       expressionS incv;
+      expressionS *p_view;
 
       if (!p->loc.u.view)
-	{
-	  p->loc.u.view = symbol_temp_make ();
-	  gas_assert (!S_IS_DEFINED (p->loc.u.view));
-	}
+	p->loc.u.view = symbol_temp_make ();
 
       memset (&incv, 0, sizeof (incv));
       incv.X_unsigned = 1;
       incv.X_op = O_symbol;
       incv.X_add_symbol = p->loc.u.view;
       incv.X_add_number = 1;
+      p_view = symbol_get_value_expression (p->loc.u.view);
+      if (p_view->X_op == O_constant || p_view->X_op == O_symbol)
+	{
+	  /* If we can, constant fold increments so that a chain of
+	     expressions v + 1 + 1 ... + 1 is not created.
+	     resolve_expression isn't ideal for this purpose.  The
+	     base v might not be resolvable until later.  */
+	  incv.X_op = p_view->X_op;
+	  incv.X_add_symbol = p_view->X_add_symbol;
+	  incv.X_add_number = p_view->X_add_number + 1;
+	}
 
       if (viewx.X_op == O_constant)
 	{
diff --git a/gas/testsuite/gas/elf/dwarf2-18.d b/gas/testsuite/gas/elf/dwarf2-18.d
index db7a4f9f20b..fbaebaa9019 100644
--- a/gas/testsuite/gas/elf/dwarf2-18.d
+++ b/gas/testsuite/gas/elf/dwarf2-18.d
@@ -2,9 +2,8 @@
 #readelf: -x.rodata -wL
 #name: DWARF2 18
 # The am33 cr16 crx ft32 mn10 msp430 nds32 and rl78 targets do not evaluate the subtraction of symbols at assembly time.
-# The mep targets turns some view computations into complex relocations.
 # The riscv targets do not support the subtraction of symbols.
-#xfail: am3*-* cr16-* crx-* ft32*-* mep-* mn10*-* msp430-* nds32*-* riscv*-* rl78-*
+#xfail: am3*-* cr16-* crx-* ft32*-* mn10*-* msp430-* nds32*-* riscv*-* rl78-*
 
 Hex dump of section '\.rodata':
   0x00000000 0100 *.*