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Re: mips-tdep.c: Sign-extend pointers for n32
- From: "Maciej W. Rozycki" <macro at mips dot com>
- To: Daniel Jacobowitz <drow at false dot org>
- Cc: gdb-patches at sourceware dot org, David Ung <davidu at mips dot com>, "Maciej W. Rozycki" <macro at linux-mips dot org>
- Date: Wed, 19 Dec 2007 15:20:20 +0000 (GMT)
- Subject: Re: mips-tdep.c: Sign-extend pointers for n32
- References: <Pine.LNX.4.61.0710251443260.22756@perivale.mips.com> <20071216184625.GA22905@caradoc.them.org>
On Sun, 16 Dec 2007, Daniel Jacobowitz wrote:
> Why just pointers? I'm not entirely sure what's going on above in the
> float case, but in the integer case this seems clearly wrong. Zero
> extension is probably "right" for trailing bits of structures but what
> about negative integers?
You are quite right here -- I have checked the N32 ABI document and it
says:
"32-bit integer (int) parameters are always sign-extended when passed in
registers, whether of signed or unsigned type. [This issue does not arise
in the o32-bit ABI.]"
It does not actually say anything about pointers beyond:
"All pointers and addresses are 32-bit objects. [Under 64, pointers and
addresses are 64bits.]"
but I gather this is because the document was meant to specify a user mode
ABI for programs run under IRIX only, so addresses with the bit #31 set
were not expected to be relevant.
I have regression-tested the following rewrite of the original patch
using the mipsisa32-sde-elf target, with the mips-sim-sde64/-mips64/-EB
and mips-sim-sde64/-mips64/-EL boards, with the results the same as the
original.
2007-12-19 David Ung <davidu@mips.com>
Maciej W. Rozycki <macro@mips.com>
* mips-tdep.c (mips_n32n64_push_dummy_call): Sign-extend 32-bit
pointers and integers as required by the ABI.
OK to apply?
Maciej
12741-0.diff
Index: binutils-quilt/src/gdb/mips-tdep.c
===================================================================
--- binutils-quilt.orig/src/gdb/mips-tdep.c 2007-12-19 15:09:31.000000000 +0000
+++ binutils-quilt/src/gdb/mips-tdep.c 2007-12-19 15:10:13.000000000 +0000
@@ -3184,8 +3184,17 @@
purpose register. */
if (argreg <= MIPS_LAST_ARG_REGNUM)
{
- LONGEST regval =
- extract_unsigned_integer (val, partial_len);
+ LONGEST regval;
+
+ /* Sign extend pointers and 32-bit integers;
+ everything else is taken as is. */
+
+ if (partial_len == 4 &&
+ (typecode == TYPE_CODE_PTR
+ || typecode == TYPE_CODE_INT))
+ regval = extract_signed_integer (val, partial_len);
+ else
+ regval = extract_unsigned_integer (val, partial_len);
/* A non-floating-point argument being passed in a
general register. If a struct or union, and if