I might be missing something here, but I don't seem to be able to get S32DS for Power v1.2 to actually use hardware floating point maths.
I created the most basic project and made sure that "Use Hardware Floating Point" is ticked, but there are no recognisable floating point instructions in the disassembly.
Unticking, making clean and rebuilding generates output that is exactly the same.
My source:
--------------------
#include "derivative.h" /* include peripheral declarations */
extern void xcptn_xmpl(void);
volatile float test;
int main(void)
{
volatile int counter = 0;
xcptn_xmpl (); /* Configure and Enable Interrupts */
/* Loop forever */
for(;;) {
counter++;
test = counter * 1.2345;
}
}
--------------------
Disassembly snippet 1:
--------------------
test = counter * 1.2345;
1003826: c2 7f se_lwz r7,8(r31)
1003828: 01 73 se_mr r3,r7
100382a: 79 ff fa a3 e_bl 10032cc <__floatsidf>
100382e: 02 40 se_mtar r8,r4
1003830: 01 37 se_mr r7,r3
1003832: 01 73 se_mr r3,r7
1003834: 03 04 se_mfar r4,r8
1003836: 70 a7 e7 f3 e_lis r5,16371
100383a: 70 b8 c0 83 e_or2i r5,49283
100383e: 70 c2 e2 6e e_lis r6,4718
1003842: 70 d2 c7 8d e_or2i r6,38797
1003846: 79 ff f8 23 e_bl 1003068 <__muldf3>
100384a: 02 40 se_mtar r8,r4
100384c: 01 37 se_mr r7,r3
100384e: 01 73 se_mr r3,r7
1003850: 03 04 se_mfar r4,r8
1003852: 79 ff fa fb e_bl 100334c <__truncdfsf2>
1003856: 01 36 se_mr r6,r3
1003858: 70 e8 e0 00 e_lis r7,16384
100385c: 54 c7 00 20 e_stw r6,32(r7)
--------------------
Disassembly snippet 2:
--------------------
010032cc <__floatsidf>:
__floatsidf():
10032cc: 18 21 06 d8 e_stwu r1,-40(r1)
10032d0: 00 80 se_mflr r0
10032d2: 7c 67 fc 70 e_srwi r7,r3,31
10032d6: 48 36 se_li r6,3
10032d8: db 01 se_stw r0,44(r1)
10032da: d2 61 se_stw r6,8(r1)
10032dc: d3 71 se_stw r7,12(r1)
10032de: 2a 03 se_cmpi r3,0
10032e0: 7a 02 00 1a e_bne 10032fa <__floatsidf+0x2e>
10032e4: 48 27 se_li r7,2
10032e6: d2 71 se_stw r7,8(r1)
10032e8: 18 61 80 08 e_addi r3,r1,8
10032ec: 78 00 01 11 e_bl 10033fc <__pack_d>
10032f0: cb 01 se_lwz r0,44(r1)
10032f2: 00 90 se_mtlr r0
10032f4: 18 21 80 28 e_addi r1,r1,40
10032f8: 00 04 se_blr
10032fa: 2a 07 se_cmpi r7,0
10032fc: 7a 12 00 0e e_beq 100330a <__floatsidf+0x3e>
1003300: 18 03 ab 80 e_cmpi cr0,r3,-2147483648
1003304: 7a 12 00 3e e_beq 1003342 <__floatsidf+0x76>
1003308: 00 33 se_neg r3
100330a: 7c 67 00 34 cntlzw r7,r3
100330e: 7c 65 0c 70 e_srwi r5,r3,1
1003312: 18 c7 84 fd e_addi r6,r7,-3
1003316: 18 87 80 1d e_addi r4,r7,29
100331a: 2a 06 se_cmpi r6,0
100331c: 7c 60 30 30 slw r0,r3,r6
1003320: 18 e7 b0 1f e_subfic r7,r7,31
1003324: 18 c4 b0 1f e_subfic r6,r4,31
1003328: 42 43 se_slw r3,r4
100332a: 7c a6 34 30 srw r6,r5,r6
100332e: d4 71 se_stw r7,16(r1)
1003330: 48 05 se_li r5,0
1003332: 7c c6 00 1e isellt r6,r6,r0
1003336: 7c 63 28 1e isellt r3,r3,r5
100333a: d6 61 se_stw r6,24(r1)
100333c: d7 31 se_stw r3,28(r1)
100333e: 79 ff ff aa e_b 10032e8 <__floatsidf+0x1c>
1003342: 70 78 e1 e0 e_lis r3,49632
1003346: 48 04 se_li r4,0
1003348: 79 ff ff a8 e_b 10032f0 <__floatsidf+0x24>
--------------------
According to VLEPEM.pdf, I was expecting to see opcodes:
efsXXXX or efdXXXX for hardware floating point instructions.
I also disassembled many of the libraries that are installed (libgcc.a) and wasn't able to find one that included any of those either - they all appeared to be using that slow software implementation shown above.
Also,
- is there a core reference manual for e200z425n3?
- is there an accurate VLE reference manual that includes all opcodes that S32DS is using? (isellt above is missing from VLEPEM.pdf)
James
