[llvm-commits] [llvm] r73387 - in /llvm/trunk: lib/CodeGen/SelectionDAG/TargetLowering.cpp test/CodeGen/X86/2009-06-15-not-a-tail-call.ll

[Arnold Schwaighofer]

Author: arnolds
Date: Mon Jun 15 09:43:36 2009
New Revision: 73387

URL: http://llvm.org/viewvc/llvm-project?rev=73387&view=rev
Log:
CheckTailCallReturnConstraints is missing a check on the
incomming chain of the RETURN node. The incomming chain must
be the outgoing chain of the CALL node. This causes the
backend to identify tail calls that are not tail calls. This
patch fixes this.

Added:
    llvm/trunk/test/CodeGen/X86/2009-06-15-not-a-tail-call.ll
Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp?rev=73387&r1=73386&r2=73387&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp Mon Jun 15 09:43:36 2009
@@ -2584,8 +2584,12 @@
   // Check that operand of the RET node sources from the CALL node. The RET node
   // has at least two operands. Operand 0 holds the chain. Operand 1 holds the
   // value.
+  // Also we need to check that there is no code in between the call and the
+  // return. Hence we also check that the incomming chain to the return sources
+  // from the outgoing chain of the call.
   if (NumOps > 1 &&
-      IgnoreHarmlessInstructions(Ret.getOperand(1)) == SDValue(TheCall,0))
+      IgnoreHarmlessInstructions(Ret.getOperand(1)) == SDValue(TheCall,0) &&
+      Ret.getOperand(0) == SDValue(TheCall, TheCall->getNumValues()-1))
     return true;
   // void return: The RET node  has the chain result value of the CALL node as
   // input.

Added: llvm/trunk/test/CodeGen/X86/2009-06-15-not-a-tail-call.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/2009-06-15-not-a-tail-call.ll?rev=73387&view=auto

==============================================================================
--- llvm/trunk/test/CodeGen/X86/2009-06-15-not-a-tail-call.ll (added)
+++ llvm/trunk/test/CodeGen/X86/2009-06-15-not-a-tail-call.ll Mon Jun 15 09:43:36 2009
@@ -0,0 +1,14 @@
+; RUN: llvm-as < %s | llc -march=x86 -tailcallopt | not grep TAILCALL 
+
+; Bug 4396. This tail call can NOT be optimized.
+
+declare fastcc i8* @_D3gcx2GC12mallocNoSyncMFmkZPv() nounwind
+
+define fastcc i8* @_D3gcx2GC12callocNoSyncMFmkZPv() nounwind {
+entry:
+	%tmp6 = tail call fastcc i8* @_D3gcx2GC12mallocNoSyncMFmkZPv()		; <i8*> [#uses=2]
+	%tmp9 = tail call i8* @memset(i8* %tmp6, i32 0, i64 2)		; <i8*> [#uses=0]
+	ret i8* %tmp6
+}
+
+declare i8* @memset(i8*, i32, i64)