https://llvm.org/bugs/show_bug.cgi?id=25289
Bug ID: 25289
Summary: [AVX-512] LLC Turns "fpext" and "fpmul" into a wrong
splitting and addition.
Product: tools
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: llc
Assignee: unassignedb...@nondot.org
Reporter: shishpanov2...@yandex.ru
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
Created attachment 15144
--> https://llvm.org/bugs/attachment.cgi?id=15144&action=edit
The IR sample.
LLC tries to extend each of two parts of "%ptr_masked_load.16" in the attached
file. It takes the first half of this vector twice, but, I guess, it should
take two different halves of this vector. For example, the assembly code, what
is the result of LLC:
f_f: # @f_f
vmovups (%rsi), %zmm0
vcvtps2pd %ymm0, %zmm1
vextractf64x4 $2, %zmm0, %ymm0
vcvtps2pd %ymm0, %zmm0
vaddpd %zmm0, %zmm0, %zmm2
vaddpd %zmm1, %zmm1, %zmm3
vmaxpd %zmm3, %zmm1, %zmm1
vmaxpd %zmm2, %zmm0, %zmm0
vcvtpd2ps %zmm1, %ymm1
vcvtpd2ps %zmm0, %ymm0
vinsertf64x4 $1, %ymm0, %zmm1, %zmm0
vmovups %zmm0, (%rdi)
retq
I think, the "vextractf64x4" takes the wrong half of %zmm0.
key for LLC launch: -mcpu=knl
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