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%default { "naninst":"mvn r0, #0" }
/*
* For the JIT: incoming arguments in r0-r1, r2-r3
* result in r0
*
* Compare two floating-point values. Puts 0, 1, or -1 into the
* destination register based on the results of the comparison.
*
* Provide a "naninst" instruction that puts 1 or -1 into r1 depending
* on what value we'd like to return when one of the operands is NaN.
*
* The operation we're implementing is:
* if (x == y)
* return 0;
* else if (x < y)
* return -1;
* else if (x > y)
* return 1;
* else
* return {-1,1}; // one or both operands was NaN
*
* The straightforward implementation requires 3 calls to functions
* that return a result in r0. We can do it with two calls if our
* EABI library supports __aeabi_cfcmple (only one if we want to check
* for NaN directly):
* check x <= y
* if <, return -1
* if ==, return 0
* check y <= x
* if <, return 1
* return {-1,1}
*
* for: cmpl-float, cmpg-float
*/
/* op vAA, vBB, vCC */
mov r9, r0 @ Save copies - we may need to redo
mov r10, r1
mov r11, lr @ save return address
mov lr, pc
ldr pc, .L__aeabi_cfcmple @ cmp <=: C clear if <, Z set if eq
bhi .L${opcode}_gt_or_nan @ C set and Z clear, disambiguate
mvncc r0, #0 @ (less than) r0<- -1
moveq r0, #0 @ (equal) r0<- 0, trumps less than
bx r11
@ Test for NaN with a second comparison. EABI forbids testing bit
@ patterns, and we can't represent 0x7fc00000 in immediate form, so
@ make the library call.
.L${opcode}_gt_or_nan:
mov r0, r10 @ restore in reverse order
mov r1, r9
mov lr, pc
ldr pc, .L__aeabi_cfcmple @ r0<- Z set if eq, C clear if <
movcc r0, #1 @ (greater than) r1<- 1
bxcc r11
$naninst @ r1<- 1 or -1 for NaN
bx r11
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