https://llvm.org/bugs/show_bug.cgi?id=30280
Bug ID: 30280
Summary: PowerPC64: issue passing packed bitfield to function
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: Backend: PowerPC
Assignee: unassignedb...@nondot.org
Reporter: an...@samba.org
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
I was looking at a csmith fail with packed bitfields. A reduced test case looks
like:
#pragma pack(1)
struct S0 {
unsigned int f1;
unsigned int f2 : 31;
unsigned int f3 : 7;
};
int foo(struct S0 a)
{
return a.f3;
}
-O0 looks ok, but at -O1 and above we seem to pull the last byte out of the
wrong spot on the stack:
std 3, -24(1)
stb 4, -16(1)
ori 2, 2, 0
lbz 3, -20(1) <---- expecting offset -16
lwz 4, -20(1)
sldi 3, 3, 32
or 3, 4, 3
rldicl 3, 3, 33, 57
blr
It also seems a bit silly to do all this work when the values were in GPRs to
start with.
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