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Fix handling of negative bitpos in expand_debug_expr
- From: Richard Sandiford <richard dot sandiford at arm dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Thu, 05 May 2016 15:20:55 +0100
- Subject: Fix handling of negative bitpos in expand_debug_expr
- Authentication-results: sourceware.org; auth=none
expand_debug_expr handled negative bit positions using:
else if (bitpos < 0)
{
HOST_WIDE_INT units
= (-bitpos + BITS_PER_UNIT - 1) / BITS_PER_UNIT;
op0 = adjust_address_nv (op0, mode1, units);
bitpos += units * BITS_PER_UNIT;
}
Here "units" is the negative of the (negative) byte offset, so I think
we should be offsetting OP0 by -units instead. E.g. a bitpos of -17
would give units==3, so this code would move OP0 up by 3 bytes and set
bitpos to 7, giving a total bitpos of 31.
Just noticed by inspection. An assert triggered for:
gcc.target/i386/mpx/bitfields-1-lbv.c
gcc.target/i386/mpx/field-addr-7-lbv.c
gcc.target/i386/mpx/reference-3-lbv.cpp
gcc.target/i386/mpx/reference-4-lbv.cpp
at -m32 but otherwise this case doesn't seem to trigger during a
bootstrap and regtest.
Tested on x86_64-linux-gnu. OK to install?
Thanks,
Richard
gcc/
* cfgexpand.c (expand_debug_expr): Fix address offset for negative
bitpos.
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 21f21c9..77a1964 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -4473,7 +4473,7 @@ expand_debug_expr (tree exp)
{
HOST_WIDE_INT units
= (-bitpos + BITS_PER_UNIT - 1) / BITS_PER_UNIT;
- op0 = adjust_address_nv (op0, mode1, units);
+ op0 = adjust_address_nv (op0, mode1, -units);
bitpos += units * BITS_PER_UNIT;
}
else if (bitpos == 0 && bitsize == GET_MODE_BITSIZE (mode))