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Correctly preserve the input chain for potential tailcall nodes whose 

return values are bitcasts.

The chain had previously been being clobbered with the entry node to
the dag, which sometimes caused other code in the function to be
erroneously deleted when tailcall optimization kicked in.

<rdar://problem/13827621>

llvm-svn: 181696
This commit is contained in:
Lang Hames 2013-05-13 10:21:19 +00:00
parent 02240c5c02
commit 67c09b3f88
2 changed files with 18 additions and 1 deletions
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2
llvm/lib/Target/ARM/ARMISelLowering.cpp
View File

@ -2147,7 +2147,7 @@ bool ARMTargetLowering::isUsedByReturnOnly(SDNode *N, SDValue &Chain) const {
Copy = *Copy->use_begin();
if (Copy->getOpcode() != ISD::CopyToReg || !Copy->hasNUsesOfValue(1, 0))
return false;
Chain = Copy->getOperand(0);
TCChain = Copy->getOperand(0);
} else {
return false;
}

17
llvm/test/CodeGen/ARM/call-tc.ll
View File

@ -162,3 +162,20 @@ define i32 @t9() nounwind {
declare %class.MutexLock* @_ZN9MutexLockC1Ev(%class.MutexLock*) unnamed_addr nounwind align 2
declare %class.MutexLock* @_ZN9MutexLockD1Ev(%class.MutexLock*) unnamed_addr nounwind align 2
; rdar://13827621
; Correctly preserve the input chain for the tailcall node in the bitcast case,
; otherwise the call to floorf is lost.
define float @libcall_tc_test2(float* nocapture %a, float %b) {
; CHECKT2D: libcall_tc_test2:
; CHECKT2D: blx _floorf
; CHECKT2D: b.w _truncf
%1 = load float* %a, align 4
%call = tail call float @floorf(float %1)
store float %call, float* %a, align 4
%call1 = tail call float @truncf(float %b)
ret float %call1
}
declare float @floorf(float) readnone
declare float @truncf(float) readnone