Fix pr3954. The register scavenger asserts for inline assembly with

register destinations that are tied to source operands.  The
TargetInstrDescr::findTiedToSrcOperand method silently fails for inline
assembly.  The existing MachineInstr::isRegReDefinedByTwoAddr was very
close to doing what is needed, so this revision makes a few changes to
that method and also renames it to isRegTiedToUseOperand (for consistency
with the very similar isRegTiedToDefOperand and because it handles both
two-address instructions and inline assembly with tied registers).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68714 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 3 deletions

diff --git a/include/llvm/CodeGen/MachineInstr.h b/include/llvm/CodeGen/MachineInstr.h
index 5c646c6874..3caf7acbae 100644
--- a/include/llvm/CodeGen/MachineInstr.h
+++ b/include/llvm/CodeGen/MachineInstr.h
@@ -241,9 +241,11 @@ public:
   /// none is found.
   int findFirstPredOperandIdx() const;
   
-  /// isRegReDefinedByTwoAddr - Given the index of a register def operand,
-  /// check if the register def is a re-definition due to two addr elimination.
-  bool isRegReDefinedByTwoAddr(unsigned DefIdx) const;
+  /// isRegTiedToUseOperand - Given the index of a register def operand,
+  /// check if the register def is tied to a source operand, due to either
+  /// two-address elimination or inline assembly constraints. Returns the
+  /// first tied use operand index by reference is UseOpIdx is not null.
+  bool isRegTiedToUseOperand(unsigned DefOpIdx, unsigned *UseOpIdx = 0);
 
   /// isRegTiedToDefOperand - Return true if the use operand of the specified
   /// index is tied to an def operand. It also returns the def operand index by