https://llvm.org/bugs/show_bug.cgi?id=23049
Bug ID: 23049
Summary: [X86] 64-bit integer stores are not always illegal on
a 32-bit system
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: Backend: X86
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
If you have SSE2, then 64-bit integer stores should be possible from an SSE
register even with i386.
$ cat st64.ll
define void @foo(i64* %p, <2 x i64> %a) {
%ext = extractelement <2 x i64> %a, i32 0
store i64 %ext, i64* %p
ret void
}
$ ./llc -march=x86 -mattr=sse2 st64.ll -o -
...
movl 4(%esp), %eax
pshufd $229, %xmm0, %xmm1 ## xmm1 = xmm0[1,1,2,3]
movd %xmm0, (%eax) <--- store low 32-bits
movd %xmm1, 4(%eax) <--- store high 32-bits
retl
GCC knows better:
_foo:
movl 4(%esp), %eax
movq %xmm0, (%eax)
ret
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