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[Patch : M32C] Fix sim for carry flag handling
- From: Kaushik Phatak <Kaushik dot Phatak at kpitcummins dot com>
- To: "binutils at sourceware dot org" <binutils at sourceware dot org>
- Cc: "dj at redhat dot com" <dj at redhat dot com>, Prafulla Thakare <Prafulla dot Thakare at kpitcummins dot com>
- Date: Tue, 19 Jan 2010 02:26:32 -0800
- Subject: [Patch : M32C] Fix sim for carry flag handling
Hi,
The following patch fixes the handling of the carry flag when the SUB
and SBB instructions are executed. The MATH_OP macro in r8c.opc
has a an extra parameter 'carryrel' to handle the relative carry in
case of result '>=' while the m32c.opc only handles cases where
result is '>'. This causes the M32C simulator to only handle the ADD
instructions correctly but it fails to set the carry flag for SUB
when the result of a subtraction is 0. This flag should be set as per
the manual and is being correctly handled in R8C and M16C.
This patch seems to fix our testcase, but causes 2 extra failures for
M32C and M32CM in DejaGnu testsuite for test case 'pointer-arith-4.c'
which performs pointer subtraction. Is the result here expected to be
zero without any carry flag or side effects?
gcc.sum file error log ->
FAIL: gcc.dg/pointer-arith-4.c (test for errors, line 40)
Please comment.
Regards,
Kaushik Phatak
www.kpitgnutools.com
=======================Start of Patch================================
Changelog
2010-01-19 Kaushik Phatak <kaushik.phatak@kpitcummins.com>
* m32c/m32c.opc (decode_m32c) : Fix MATH_OP for carry in SUB insn
diff -rNup scr.orig/sim/m32c/m32c.opc src/sim/m32c/m32c.opc
--- scr.orig/sim/m32c/m32c.opc 2009-01-14 16:23:07.000000000 +0530
+++ src/sim/m32c/m32c.opc 2010-01-18 15:01:41.000000000 +0530
@@ -125,7 +125,8 @@ prefix (src_allowed, dest_allowed, index
mb = sign_ext (s, dc.bytes * 8); \
v = ma op mb op c; \
tprintf("%d " #op " %d " #op " %d = %d\n", ma, mb, c, v); \
- set_oszc (v, dc.bytes, ll > ((1 op 1) ? b2mask[dc.bytes] : 0)); \
+ set_oszc (v, dc.bytes, (#op=="+") ? ll > ((1 op 1) ? \
+ b2mask[dc.bytes] : 0) : ll >= ((1 op 1) ? b2mask[dc.bytes] : 0) ); \
put_dest (dc, v); \
}
=========================End Of Patch================================