https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71119
Bug ID: 71119
Summary: [4.9 Regression] ftoit instruction not emitted for
double -> long bitcast
Product: gcc
Version: 4.9.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: mattst88 at gmail dot com
Target Milestone: ---
Created attachment 38491
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38491&action=edit
ftoit.c
For the attached ftoit.c, gcc-4.8.5 -O2 -mcpu=ev67 emits
0000000000000000 <f2i>:
0: 00 0e 1f 72 ftoit $f16,v0
4: 00 00 e0 43 sextl v0,v0
8: 01 80 fa 6b ret
c: 00 00 fe 2f unop
0000000000000010 <f2l>:
10: 00 0e 1f 72 ftoit $f16,v0
14: 01 80 fa 6b ret
18: 1f 04 ff 47 nop
1c: 00 00 fe 2f unop
while gcc-4.9.3/gcc-5.3.0 -O2 -mcpu=ev67 emits
0000000000000000 <f2i>:
0: 00 0e 1f 72 ftoit $f16,v0
4: 00 00 e0 43 sextl v0,v0
8: 01 80 fa 6b ret
c: 00 00 fe 2f unop
0000000000000010 <f2l>:
10: f0 ff de 23 lda sp,-16(sp)
14: 00 00 1e 9e stt $f16,0(sp)
18: 00 00 1e a4 ldq v0,0(sp)
1c: 10 00 de 23 lda sp,16(sp)
20: 01 80 fa 6b ret
24: 00 00 fe 2f unop
28: 1f 04 ff 47 nop
2c: 00 00 fe 2f unop
In fact, the alpha architecture reference says that ftoit is exactly equivalent
to an stt/ldq sequence.
f2l should have used ftoit, as with gcc-4.8.5.
