https://bugs.llvm.org/show_bug.cgi?id=32442
Bug ID: 32442
Summary: [ppc] redundant zero extension when returning bool
value
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Backend: PowerPC
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Compile the following code with options -m64 -O2 -mvsx -mcpu=power8
bool foo(int i, int* p) {
if (i==0)
return false;
*p = i;
return true;
}
LLVM generates:
_Z3fooiPi: # @_Z3fooiPi
.Lfunc_begin0:
# BB#0: # %entry
cmplwi 3, 0
beq 0, .LBB0_2
# BB#1: # %if.end
stw 3, 0(4)
li 3, 1
clrldi 3, 3, 32 // redundant
blr
.LBB0_2:
li 3, 0
clrldi 3, 3, 32 // redundant
blr
The problem is when PPCBoolRetToInt.cpp converts the old the old cmp/isel
behavior into today's integer operation, it uses i32 type, on ppc64, it needs
to be zero extended to 64bit before return. We should use i64 on ppc64 and i32
on ppc32.
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