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Fix an over-constrained assertion in MachineFunction::addLiveIn. 

The assertion was checking that the virtual register VReg used to represent the
physical register PReg uses the same register class as the one passed to
MachineFunction::addLiveIn.
This is over-constraining because it is sufficient to check that the register
class of VReg (VRegRC) is a subclass of the register class of PReg (PRegRC) and
that VRegRC contains PReg.
Indeed, if VReg gets constrained because of some operation constraints
between two calls of MachineFunction::addLiveIn, the original assertion
cannot match.

This fixes <rdar://problem/15633429>. 

llvm-svn: 197097
This commit is contained in:
Quentin Colombet 2013-12-12 00:15:47 +00:00
parent 6f4f77b7e9
commit 18b779e3f4
2 changed files with 34 additions and 1 deletions
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11
llvm/lib/CodeGen/MachineFunction.cpp
View File

@ -425,7 +425,16 @@ unsigned MachineFunction::addLiveIn(unsigned PReg,
MachineRegisterInfo &MRI = getRegInfo();
unsigned VReg = MRI.getLiveInVirtReg(PReg);
if (VReg) {
assert(MRI.getRegClass(VReg) == RC && "Register class mismatch!");
const TargetRegisterClass *VRegRC = MRI.getRegClass(VReg);
(void)VRegRC;
// A physical register can be added several times.
// Between two calls, the register class of the related virtual register
// may have been constrained to match some operation constraints.
// In that case, check that the current register class includes the
// physical register and is a sub class of the specified RC.
assert((VRegRC == RC || (VRegRC->contains(PReg) &&
RC->hasSubClassEq(VRegRC))) &&
"Register class mismatch!");
return VReg;
}
VReg = MRI.createVirtualRegister(RC);

24
llvm/test/CodeGen/AArch64/assertion-rc-mismatch.ll Normal file
View File

@ -0,0 +1,24 @@
; RUN: llc < %s -mtriple=aarch64-none-linux-gnu | FileCheck %s
; Test case related to <rdar://problem/15633429>.
; CHECK-LABEL: small
define i64 @small(i64 %encodedBase) {
cmp:
%lnot.i.i = icmp eq i64 %encodedBase, 0
br i1 %lnot.i.i, label %if, label %else
if:
%tmp1 = call i8* @llvm.returnaddress(i32 0)
br label %end
else:
%tmp3 = call i8* @llvm.returnaddress(i32 0)
%ptr = getelementptr inbounds i8* %tmp3, i64 -16
%ld = load i8* %ptr, align 4
%tmp2 = inttoptr i8 %ld to i8*
br label %end
end:
%tmp = phi i8* [ %tmp1, %if ], [ %tmp2, %else ]
%coerce.val.pi56 = ptrtoint i8* %tmp to i64
ret i64 %coerce.val.pi56
}
declare i8* @llvm.returnaddress(i32)