[llvm] r181696 - Correctly preserve the input chain for potential tailcall nodes whose

[Lang Hames]

Author: lhames
Date: Mon May 13 05:21:19 2013
New Revision: 181696

URL: http://llvm.org/viewvc/llvm-project?rev=181696&view=rev
Log:
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>

Modified:
    llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
    llvm/trunk/test/CodeGen/ARM/call-tc.ll

Modified: llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp?rev=181696&r1=181695&r2=181696&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp Mon May 13 05:21:19 2013
@@ -2147,7 +2147,7 @@ bool ARMTargetLowering::isUsedByReturnOn
     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;
   }

Modified: llvm/trunk/test/CodeGen/ARM/call-tc.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/call-tc.ll?rev=181696&r1=181695&r2=181696&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/call-tc.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/call-tc.ll Mon May 13 05:21:19 2013
@@ -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