Treat clobber operands like early clobbers: if we have

any, we force sdisel to do all regalloc for an asm.  This
leads to gross but correct codegen.

This fixes the rest of PR2078.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47454 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 16 insertions, 0 deletions

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index def4f9a018..e159c111de 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -3467,6 +3467,17 @@ void AsmOperandInfo::ComputeConstraintToUse(const TargetLowering &TLI) {
 }
 
 
+/// GetRegistersForValue - Assign registers (virtual or physical) for the
+/// specified operand.  We prefer to assign virtual registers, to allow the
+/// register allocator handle the assignment process.  However, if the asm uses
+/// features that we can't model on machineinstrs, we have SDISel do the
+/// allocation.  This produces generally horrible, but correct, code.
+///
+///   OpInfo describes the operand.
+///   HasEarlyClobber is true if there are any early clobber constraints (=&r)
+///     or any explicitly clobbered registers.
+///   Input and OutputRegs are the set of already allocated physical registers.
+///
 void SelectionDAGLowering::
 GetRegistersForValue(AsmOperandInfo &OpInfo, bool HasEarlyClobber,
                      std::set<unsigned> &OutputRegs, 
@@ -3723,6 +3734,11 @@ void SelectionDAGLowering::visitInlineAsm(CallSite CS) {
     // Keep track of whether we see an earlyclobber.
     SawEarlyClobber |= OpInfo.isEarlyClobber;
     
+    // If we see a clobber of a register, it is an early clobber.
+    if (OpInfo.Type == InlineAsm::isClobber &&
+        OpInfo.ConstraintType == TargetLowering::C_Register)
+      SawEarlyClobber = true;
+    
     // If this is a memory input, and if the operand is not indirect, do what we
     // need to to provide an address for the memory input.
     if (OpInfo.ConstraintType == TargetLowering::C_Memory &&