When x86 addresses matching exceeds its recursion limit, check to

see if the base register is already occupied before assuming it can be
used. This fixes bogus code generation in the accompanying testcase.

llvm-svn: 41049

1 files changed, 12 insertions, 6 deletions

diff --git a/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp b/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
index f0331b83a1a..812d2ecbd2d 100644
--- a/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ b/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -142,6 +142,8 @@ namespace {
 
     bool MatchAddress(SDOperand N, X86ISelAddressMode &AM,
                       bool isRoot = true, unsigned Depth = 0);
+    bool MatchAddressBase(SDOperand N, X86ISelAddressMode &AM,
+                          bool isRoot, unsigned Depth);
     bool SelectAddr(SDOperand Op, SDOperand N, SDOperand &Base,
                     SDOperand &Scale, SDOperand &Index, SDOperand &Disp);
     bool SelectLEAAddr(SDOperand Op, SDOperand N, SDOperand &Base,
@@ -572,12 +574,9 @@ void X86DAGToDAGISel::EmitFunctionEntryCode(Function &Fn, MachineFunction &MF) {
 /// addressing mode
 bool X86DAGToDAGISel::MatchAddress(SDOperand N, X86ISelAddressMode &AM,
                                    bool isRoot, unsigned Depth) {
-  if (Depth > 5) {
-    // Default, generate it as a register.
-    AM.BaseType = X86ISelAddressMode::RegBase;
-    AM.Base.Reg = N;
-    return false;
-  }
+  // Limit recursion.
+  if (Depth > 5)
+    return MatchAddressBase(N, AM, isRoot, Depth);
   
   // RIP relative addressing: %rip + 32-bit displacement!
   if (AM.isRIPRel) {
@@ -763,6 +762,13 @@ bool X86DAGToDAGISel::MatchAddress(SDOperand N, X86ISelAddressMode &AM,
     break;
   }
 
+  return MatchAddressBase(N, AM, isRoot, Depth);
+}
+
+/// MatchAddressBase - Helper for MatchAddress. Add the specified node to the
+/// specified addressing mode without any further recursion.
+bool X86DAGToDAGISel::MatchAddressBase(SDOperand N, X86ISelAddressMode &AM,
+                                       bool isRoot, unsigned Depth) {
   // Is the base register already occupied?
   if (AM.BaseType != X86ISelAddressMode::RegBase || AM.Base.Reg.Val) {
     // If so, check to see if the scale index register is set.