* [RFA] Fix for mcore simulator
@ 2023-10-04 22:09 Jeff Law
2023-10-05 10:14 ` Nick Clifton
0 siblings, 1 reply; 2+ messages in thread
From: Jeff Law @ 2023-10-04 22:09 UTC (permalink / raw)
To: Binutils
[-- Attachment #1: Type: text/plain, Size: 1163 bytes --]
I was looking for cases where a GCC patch under evaluation would cause
test results to change. Quite surprisingly the mcore-elf port showed
test differences. After a fair amount of digging my conclusion was the
sequences before/after the patch should have been semantically the same.
Of course if the code is supposed to behave the same, then that points
to problems elsewhere (assembler, linker, simulator). Sure enough the
mcore simulator was mis-handling the sign extension instructions. The
simulator implementation of sextb is via paired shift-by-24 operations.
Similarly the simulator implements sexth via paired shift-by-16 operations.
The temporary holding the value was declared as a "long" thus this
approach worked fine for hosts with a 32 bit wide long and failed
miserably for hosts with a 64 bit wide long.
This patch makes the shift count automatically adjust based on the size
of the temporary. It includes a simple test for sextb and sexth. I
have _not_ done a full audit of the mcore simulator for more 32->64 bit
issues.
This also fixes 443 execution tests in the GCC testsuite ;-)
OK for the trunk?
Thanks,
Jeff
[-- Attachment #2: mcore-sim.patch --]
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diff --git a/sim/mcore/interp.c b/sim/mcore/interp.c
index 53cfdad050b..48d9ff8645a 100644
--- a/sim/mcore/interp.c
+++ b/sim/mcore/interp.c
@@ -641,8 +641,8 @@ step_once (SIM_DESC sd, SIM_CPU *cpu)
{
long tmp;
tmp = gr[RD];
- tmp <<= 24;
- tmp >>= 24;
+ tmp <<= (sizeof (tmp) * 8) - 8;
+ tmp >>= (sizeof (tmp) * 8) - 8;
gr[RD] = tmp;
}
break;
@@ -653,8 +653,8 @@ step_once (SIM_DESC sd, SIM_CPU *cpu)
{
long tmp;
tmp = gr[RD];
- tmp <<= 16;
- tmp >>= 16;
+ tmp <<= (sizeof (tmp) * 8) - 16;
+ tmp >>= (sizeof (tmp) * 8) - 16;
gr[RD] = tmp;
}
break;
diff --git a/sim/testsuite/mcore/sextb.s b/sim/testsuite/mcore/sextb.s
new file mode 100644
index 00000000000..5500f7abe67
--- /dev/null
+++ b/sim/testsuite/mcore/sextb.s
@@ -0,0 +1,25 @@
+# check that sext.b/sext.h work correctly
+# mach: mcore
+
+.include "testutils.inc"
+
+ start
+ # Construct -120 using bgeni+addi+sext
+ bgeni r2, 7
+ addi r2,8
+ sextb r2
+
+ # Construct -120 using movi+not
+ movi r7,119
+ not r7
+
+ # Compare them, they should be equal
+ cmpne r2,r7
+ jbt .L1
+ pass
+.L1:
+ fail
+
+
+
+
diff --git a/sim/testsuite/mcore/sexth.s b/sim/testsuite/mcore/sexth.s
new file mode 100644
index 00000000000..97279c49ed4
--- /dev/null
+++ b/sim/testsuite/mcore/sexth.s
@@ -0,0 +1,27 @@
+# check that sext.b/sext.h work correctly
+# mach: mcore
+
+.include "testutils.inc"
+
+ start
+ # Construct -32760 using bgeni+addi+sext
+ bgeni r2, 15
+ addi r2,8
+ sexth r2
+
+ # Construct -32760 using bmask+subi+not
+ bmaski r7,15
+ subi r7,8 // 32759 0x7ff7
+ not r7
+
+
+ # Compare them, they should be equal
+ cmpne r2,r7
+ jbt .L1
+ pass
+.L1:
+ fail
+
+
+
+
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [RFA] Fix for mcore simulator
2023-10-04 22:09 [RFA] Fix for mcore simulator Jeff Law
@ 2023-10-05 10:14 ` Nick Clifton
0 siblings, 0 replies; 2+ messages in thread
From: Nick Clifton @ 2023-10-05 10:14 UTC (permalink / raw)
To: Jeff Law, Binutils
Hi Jeff,
> This patch makes the shift count automatically adjust based on the size of the temporary. It includes a simple test for sextb and sexth. I have _not_ done a full audit of
> the mcore simulator for more 32->64 bit issues.
>
> This also fixes 443 execution tests in the GCC testsuite ;-)
Yay!
> OK for the trunk?
No - because the sim sources are part of GDB not the binutils, so
you need to post the patch to their mailing list.
But if it helps I would definitely recommend that they approve the patch. :-)
Cheers
Nick
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