This reapplies r207235 with an additional bugfixes caught by the msan

buildbot - do not insert debug intrinsics before phi nodes.

Debug info for optimized code: Support variables that are on the stack and
described by DBG_VALUEs during their lifetime.

Previously, when a variable was at a FrameIndex for any part of its
lifetime, this would shadow all other DBG_VALUEs and only a single
fbreg location would be emitted, which in fact is only valid for a small
range and not the entire lexical scope of the variable. The included
dbg-value-const-byref testcase demonstrates this.

This patch fixes this by
Local
- emitting dbg.value intrinsics for allocas that are passed by reference
- dropping all dbg.declares (they are now fully lowered to dbg.values)
SelectionDAG
- renamed constructors for SDDbgValue for better readability.
- fix UserValue::match() to handle indirect values correctly
- not inserting an MMI table entries for dbg.values that describe allocas.
- lowering dbg.values that describe allocas into *indirect* DBG_VALUEs.
CodeGenPrepare
- leaving dbg.values for an alloca were they are (see comment)
Other
- regenerated/updated instcombine.ll testcase and included source

rdar://problem/16679879
http://reviews.llvm.org/D3374

llvm-svn: 207269

1 files changed, 12 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index f3974461da5..6ebedfc67af 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5646,21 +5646,26 @@ SDNode *SelectionDAG::getNodeIfExists(unsigned Opcode, SDVTList VTList,
 
 /// getDbgValue - Creates a SDDbgValue node.
 ///
+/// SDNode
 SDDbgValue *
-SelectionDAG::getDbgValue(MDNode *MDPtr, SDNode *N, unsigned R, uint64_t Off,
+SelectionDAG::getDbgValue(MDNode *MDPtr, SDNode *N, unsigned R,
+			  bool IsIndirect, uint64_t Off,
                           DebugLoc DL, unsigned O) {
-  return new (Allocator) SDDbgValue(MDPtr, N, R, Off, DL, O);
+  return new (Allocator) SDDbgValue(MDPtr, N, R, IsIndirect, Off, DL, O);
 }
 
+/// Constant
 SDDbgValue *
-SelectionDAG::getDbgValue(MDNode *MDPtr, const Value *C, uint64_t Off,
-                          DebugLoc DL, unsigned O) {
+SelectionDAG::getConstantDbgValue(MDNode *MDPtr, const Value *C,
+				  uint64_t Off,
+				  DebugLoc DL, unsigned O) {
   return new (Allocator) SDDbgValue(MDPtr, C, Off, DL, O);
 }
 
+/// FrameIndex
 SDDbgValue *
-SelectionDAG::getDbgValue(MDNode *MDPtr, unsigned FI, uint64_t Off,
-                          DebugLoc DL, unsigned O) {
+SelectionDAG::getFrameIndexDbgValue(MDNode *MDPtr, unsigned FI, uint64_t Off,
+				    DebugLoc DL, unsigned O) {
   return new (Allocator) SDDbgValue(MDPtr, FI, Off, DL, O);
 }
 
@@ -6066,6 +6071,7 @@ void SelectionDAG::TransferDbgValues(SDValue From, SDValue To) {
     SDDbgValue *Dbg = *I;
     if (Dbg->getKind() == SDDbgValue::SDNODE) {
       SDDbgValue *Clone = getDbgValue(Dbg->getMDPtr(), ToNode, To.getResNo(),
+				      Dbg->isIndirect(),
                                       Dbg->getOffset(), Dbg->getDebugLoc(),
                                       Dbg->getOrder());
       ClonedDVs.push_back(Clone);