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>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181696 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index fd777323642309c803d3fe1bee464405816c0457..008edbe4a75ba6a287c2146195efc2d422b545b8 100644 (file)
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -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;
   }

diff --git a/test/CodeGen/ARM/call-tc.ll b/test/CodeGen/ARM/call-tc.ll
index 58fbbda0f6bdd8e667a1050129eb948b61a765fa..c7e17ea353f38272435da7a4d0fa754597714051 100644 (file)
--- a/test/CodeGen/ARM/call-tc.ll
+++ b/test/CodeGen/ARM/call-tc.ll
@@ -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