AN2203 Freescale Semiconductor / Motorola, AN2203 Datasheet - Page 55

• Manufacturer Part Number: AN2203
• Description: MPC7450 RISC Microprocessor Family Software Optimization Guide
• Manufacturer: Freescale Semiconductor / Motorola

5.3
Table 5-3 shows the code sequences from Section D.2 of the PowerPC Compiler Writer’s Guide. In each
example, v0 is located in r3 and v1 is located in r4.
MOTOROLA
ltu/gtu
r = (unsigned_word) v0 < (unsigned_word) v1
r = (unsigned_word) v1 > (unsigned_word) v0;
eq0
r = (v0 == 0);
ne0
r = (v0 != 0);
les0
r = (signed_word) v0 <= 0
ges0
r = (signed_word) v0 >= 0;
lts0
r = (signed_word) v0 < 0;
gts0
r = (signed_word) v0 > 0;
Negated Comparisons and Negated Comparisons
Against Zero
MPC7450 RISC Microprocessor Family Software Optimization Guide
Table 5-2. Comparisons and Comparisons Against Zero (continued)
Operation
Freescale Semiconductor, Inc.
For More Information On This Product,
Negated Comparisons and Negated Comparisons Against Zero
Go to: www.freescale.com
subfc r5,r4,r3
subfe r6,r6,r6
neg r7,r6
Cycles: 5
subfic r4,r3,0
adde r5,r4,r3
Cycles: 4
addic r4,r3,-1
subfe r5,r4,r3
Cycles: 4
neg r4,r3
orc r5,r3,r4
srwi r6,r5,31
Cycles: 3
srwi r4,r3,31
xori r5,r4,1
Cycles: 2
srwi r4,r3,31
Cycles: 1
neg r4,r3
andc r5,r4,r3
srwi r6,r5,31
Cycles: 3
Compiler Writer’s
Guide Code
xor r5,r4,r3
cntlzw r6,r5
slw r7,r4,r6
srwi r8,r7,31
Cycles: 4
cntlzw r4,r3
srwi r5,r4,5
Cycles: 2
neg r4,r3
or r5,r4,r3
srwi r6,r5,31
Cycles: 3
li r4,1
cntlzw r5,r3
rlwnm r6,r4,r5,31,31
Cycles: 2
MPC7450 Code
(If Different)
Both sequences are
listed in the PowerPC
Compiler Writer’s
Guide, with the
subfic and adde
sequence being first.
The cntlzw and srwi
sequence is
preferred.
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